I have been collecting information about Fiero’s for some time and thought I should place what I found and my projects online for others to see. You will find articles I have found or wrote on all different areas about the Pontiac Fiero. Most of the information you will find here have something to do with one of my Fiero project I have done or am looking at doing. As I start and work on a project you will find it under “My Project”.

You will notice that I have articles from other sites. I don’t mean to steel anything, but what I have been finding is that sites with good information are going away, along with the information. So when I find a good article on a site that I may want to use in the future I will copy it, so I can get to it when I need to. I have been running a very small hosting service for almost 10 years now and I don’t see that changing any time in the next 10 years. So as long as I have the resources available I will be archiving it for all to use.

Anyway have a look around and let me know what you think.

Chuck

Sorry, not really a club. Just massing around.

A major problem? Why?

The ECM will try to compensate for leaks up to a certain size. The leak will often cause performance problems without setting DTCs in the ECM. Depending on exactly where the leak is, it can unbalance the entire engine.
Let’s say you’ve got an Iron Duke and the EGR is leaking slightly around the base. This allows air to enter the intake right near the middle cylinders, leaning them out just a little. The ECM tries to make up for this by increasing the fuel feed. The end result is that the end cylinders are probably running rich. The car may seem to run pretty normally but you’ll take a hit in fuel economy and most likely you’ll have strange drivability problems that are often hard to duplicate.
Any vacuum leak is letting air in after the IAC and Throttle Plate. The ECM tries to make up for this by closing the IAC and likely increasing the fuel flow. This can cause a number of odd things to happen, like goofy Idle and hesitation. Ultimately, there is no such thing as an acceptable vacuum leak. All leaks must be found and fixed.

Tools:

Spray can of “throttle body” and Fuel Injection cleaner. (This is safe for all EFI. Carburetor cleaners can sometimes do damage to EFI parts. Don’t use it.) ((I do NOT recommend most people use the propane search method. It is far to easy to start a fire with this method, especially if done with improvised equipment.))
Assorted line plugs and port caps.
Hand operated vacuum pump such as “Mighty Vac” or equivalent. If you are buying one of these, just get the whole vacuum brake bleeding kit. Then you’ll get more use from it and bleed the brakes or clutch allot faster.

General:

Eliminate the nonessential items first. Start the car after each of the following and see if it has solved your problem.
Disconnect the 2 lines to the Fuel Vapor Recovery canister. Plug the ports on the throttle body and/or manifold.
Disconnect the Cruise Control line and plug its manifold port.
Disconnect the EGR line from the throttle body and cap its port. (I’ll get more into the EGR later)
In the front compartment disconnect and plug the line on the brake booster. DO NOT attempt to drive the car with the booster disabled! The brake booster can leak internally. Carefully inspect the booster vacuum line and all it’s clamps. All joints in this line should be clamped and the rubber hose sections free of cracks or other damage. Make sure there are no rusted sections of steel line. (The section inside the cabin is likely OK.) If any section of the line looks questionable spray the suspect area with EFI cleaner. Check the line to the MAP sensor carefully. Hard line doesn’t like being bent, especially when cold. (DO NOT spray the MAP sensor with solvent when searching for a vacuum leak!)
If the above have not solved the problem then carefully begin searching with the spray cleaner. Start the car and spray the throttle body mountings and work your way around whatever isn’t disconnected. DO NOT spray the distributor, coil(s), sensors or IAC with cleaners or solvents! You will likely damage them or start a fire. Use as little spray as possible to find the leak.
Don’t soak things. Test an area, let it dry then test another. The RPMs should change one way or the other when you spray the leak.

Fuel Vapor Recovery Canister:

This device catches vapor from the fuel tank. It uses 2 vacuum lines. The large (purge) line is connected to manifold vacuum. This line is used to ventilate the canister. The smaller (control) line is connected to the main bore of the throttle body and only opens the purge valve beyond a certain amount of throttle.
Problems with the canister can include failure of the purge valve to close and cracks in the purge valve body or canister itself.
There is also a fiber filter in the bottom of the canister that should be replaced periodically.
Another problem that this device can develop is flooding. Flooding is caused when liquid fuel is forced up the vent line into the canister. A flooded canister can cause rich mix problems with the engine. A canister that has been flooded should be replaced. To prevent flooding avoid “topping off” the fuel tank when you fill up. If the nozzle of a retail fuel pump is defective, and they often are, then you can pressurize the fuel tank and force fuel up the vent line into the vapor canister. It doesn’t take allot of liquid fuel to screw up the canister. Even if the pump doesn’t force fuel into the canister, fuel expansion in the tank can and often will. Either way, topping off the tank is a bad idea.

Quick test….

Disconnect both lines and connect a hand vacuum pump to the large line. Give the pump a squeeze and make sure the line holds vacuum. 10 inches is plenty of vacuum for this test.
Now use the pump on the small line. Draw only 3-4 inches maximum on this line! More than a few inches vacuum can damage it. While you have vacuum on the control line, blow into the purge line. Air should move freely. While blowing into the purge line release the vacuum on the control line. The valve should close and block all airflow in the purge line.

Cruise Control:

Leaks in the cruise control servo diaphragm cannot be fixed. Some people have had luck cleaning the valves on the servo and/or the dump valve. (The dump valve is a backup valve that kills the cruise when the brake is pressed and is mounted separately from cruise servo.)
There is also a vacuum reserve canister in the cruise system. Older style canisters are often metal and are prone to rusting out. Replace these with new style plastic canisters.
There are 2 styles of canister. The ones with 2 fittings usually have integral check valves. The ones with single ports are used with a check valve in the manifold line.
You can replace the can and inline check valve with a 2 port vacuum ball, but you must also insure that the plumbing is redone to work correctly. I think the larger port on these is usually the manifold side but test it to make sure. The exact size of the canister is not very critical. Any canister of approximately the same volume or greater will work. You can get good used plastic canisters for about nothing at any salvage yard. The plastic ones will last nearly forever. Just make sure the check valve is working before you leave the yard. (Blowing into one port is very easy. The other is not going to let you if the valve works.)
BTW: You can get these from many American made cars. It doesn’t have to be a GM product.

As you can see, changing to the vacuum ball also simplifies the vacuum lines quite a bit. If you make this change, and cruise stops working, then you may have put the lines on the Vac Ball wrong.

Brake booster:

The brake booster unit should not be disassembled. If you believe it leaks then it will need to be replaced. You generally can’t get parts for the booster and there is a very heavy spring inside it that likes to send thing flying.
The check valve that the vacuum line connects to can go bad. This usually manifests as brakes that work right only at idle. The check valve shell can crack and cause a vacuum leak. You can replace the valve by itself. Try MotorMite’s HELP! or VacuTite lines.
Don’t forget to check the brake filter on cars that have them. The plastic shell of them is pretty tough but it can crack or melt. The brake filter does need to be replaced on occasion. If it plugs up you will have brake problems.

Hard lines:

Hard vacuum line can be a pain to service. You can get the line but finding the correct fittings can be difficult at best. (The rubber fittings are reusable if they are in good condition and sealing tightly to both the line and the port.) If you replace hard line with soft line make sure the new lines are not pinched or collapsed from bending too tightly. The soft line should be sized to properly slide onto the fittings and stay tight. Don’t stretch undersized line to fit. It will likely split in short order.
New Hard Line can be shaped or straightened by careful use of heat. (Try dipping the line in very hot water.) Be careful not to pinch or stretch the softened line. Don’t try to form old lines. They usually break even when warmed.
Note: If you replace the MAP sensor line with soft line then keep the line as short as possible. The soft line will have a larger internal volume per inch of line than the hard line. This increased volume can affect the reaction time of the MAP sensor. A slow MAP sensor will likely hurt performance. Even when using hard line it is best to keep the MAP feed short as possible.
Make sure the steel PCV valve line is not rusted through anyplace and that both elbows are sealed. GM recommends clamps on the elbows. Be careful with the clamps that you don’t cut into the soft elbows.

4 Cylinder specific:

The 4 cylinder EGR is bolted directly to the intake manifold. Make sure it’s tight. The bolts have a nasty habit of coming loose. Replace the gasket if the bolts have come loose at all. (The FelPro EGR gasket costs about $1.00 at most parts stores.)
The EGR valve is hard to test for leakage. Make sure the valve isn’t binding.
One way to test EGR problems is to make a block off plate and seal the manifold openings. Then run without it for a little bit. Note: Permanently running the car without the EGR is a crime in the United States. Running the car without the EGR can cause detonation, which can damage the engine. This is a testing procedure only.

87-88 TBI:

Be careful not to spray the MAT sensor’s plastic parts with solvent. Depending on the solvent used, you can damage the sensor. The MAT sensor is located to the right of the TBI unit and is screwed into the intake manifold. Avoid intake backfires in these engines. If the car backfires into the intake, the MAT sensor should be inspected for damage. If the MAT sensor has been cooked it should be replaced. (The MAT sensor is used in calculating fuel/air ratio.) Don’t over tighten the MAT sensor or you may split the intake manifold.
Check the base of the TBI for leaking, especially if there is any evidence the air cleaner has hit the trunk wall. (Read the torque strut article.) There is a specific sequence to tighten the 700 TBI to the manifold. Read the TBI 700 article. The emissions vacuum line map for these years is in the TBI 700 article. That map doesn’t include cruise.

V6 specific:

You’ll need to check the EGR plumbing very carefully. Use extreme caution if you decide to use spray or gas searching on this. The V6 EGR plumbing gets hot enough to light off many solvents on contact.
The V6 EGR control valve must also work properly. If it’s acting up, try electronics parts cleaner. Don’t use the cleaners with lubricant in them. The lubricants will hold dirt and quickly clog the valve up again. (Most “Tuner wash” and contact cleaners have lubricants in them.)
To test this valve, with the engine off, blow into the line connected to the EGR valve. The air should exit the vent hole. Cap the vent hole and blow again into the EGR port. No air should come out the manifold port.
To test during run, connect a vacuum gauge to a T in the EGR valve line. You should be able to see the vacuum rise and fall when the ECM has activated the EGR valve. Using an ECM scanner with the vacuum gauge may be helpful. I think the ECM will tell you when it’s trying to open/shut the EGR. You should see a corresponding change on the gauge. (I think the ECM may also report the EGR vacuum sensor status. I can never remember just what ECM reports what.) You must also carefully inspect the entire plenum. If bolts have come loose you may be able to simply tighten them but likely you will need to replace the gaskets.
Rodney Dickman now offers formed metal vacuum lines for the V6.

Warning! Don’t force anything into the ALDL connector! If you damage the connector then you can have problems when using ECM scanners and other tools that have the proper size terminals.

Note! It is possible that the ALDL may be installed with the Key up or down.
The above picture is Key Down. Use the key sticking off the ALDL by terminals C & D to determine which way the ALDL is positioned.
With the key down, when you are sitting in the drivers seat, Terminal A is on the bottom row on the passenger’s side. With the key up A is the top terminal closest you.
To read ECM codes short terminals A & B together and turn the key to run, codes will blink thru the Service Engine Soon light. (Don’t start the car!)
Terminal F is used for some tests of the Torque Converter Lockup System. See the TH125 article for more information.
Terminal G is the fuel pump test point. It will have 12V on it whenever the pump is on. It can also be used to feed 12V to the pump to determine if the pump or the controls are a problem.
None of the other terminals are used during normal service routines so leave them alone. If you short them out you could do major damage to the ECM. (Only a few terminals in the ALDL are even wired.)
You can find the complete pin out of this connector and others here –> Fiero Tech Zone He also has a brief ECM code list.
There is a cheap tool to read codes in the tool section of most parts stores. It is a simple stamped metal item and cost about $2. You can also use any wire that will make snug contact.
If you have an Autozone store near you ask the counter man for the book and key to read the codes. The book is titled “What Does It Mean When Your `Check Engine’ Light Comes On?” This small book lists common codes for GM Ford and Chrysler and how to test some of the ECM sensors. The book is free.
The best tool for dealing with the ECM is a scanner. These tools read the full data stream from the ECM and will report data from sensors and how the ECM is reacting to it. The AutoXray GM OBD-1 scanner is one of many tools available and cost about $150-200. Other scanners are available but most cost more.

Notes:

1. These are electrically pretty much the same. The difference is mostly in the method of mounting.
2. Don’t use Teflon thread sealing tape on grounded shell NPT sensors. It will likely interfere with getting a good electrical connection through the threads.
3. ECM coolant, MAT, and ACT, use the same value NTC thermistor internally. The test table, in another article, applies to all of them. (An NTC Thermistor is a temperature sensitive resistor that drops in resistance as temperature rises.)
4. MAT and ACT are essentially the same sensor with different names based on location of the sensor. ACT sensors often tend to use epoxy-coated thermistors while MAT is not coated. Sensors without the coating are a little faster responding than coated ones. This is rather important for MAT where it can see 20+F temperature changes in a couple seconds. An ACT sensor, because of its location in the air cleaner of the V6 can be a little slower and still function correctly. Uncoated sensors will always have a plastic guard cage.
5. The PIM on distributor motors is normally screwed to the distributor. The PIM on DIS motors is sandwiched in between the coils and the aluminum mounting plate. The crank position sensor is under the DIS mounting plate.
6. Always check engine grounds whenever there is a problem with the O2 sensor. This sensor generates only 1VDC max. Grounding problems can cause the ECM to read the wrong voltage.
7. The TPS is a mechanical sensor and is subject to wear contamination and breakage. The TPS is the only sensor in Fiero with moving parts.
8. This sensor measures pressure with a solid-state transducer. The top or bottom of this sensor may have vent holes. Do not allow solvents to enter the vent holes as you could ruin the transducer.
9. Lobes, vanes, flaps, whatever favorite name for them is…
10. No. You can’t convert a distributor motor to DIS or the other way around. The crank isn’t the only issue.
11. Early model 4 cylinder applications may use a 2 speed fan. According to GM schematics this fan has 2 senders. One sender is a single switch that activates at 235F. The other sender has 2 switches that activate at 221F and 246F. The low speed will activate when the 221 or the 235 contacts close or when the air conditioning is on. High speed will activate only when the 241 contacts close.
12. All repairs to the wiring of this sensor MUST be soldered and water proofed. Corrosion of improperly repaired joints will result in bogus ECM errors.
13. The original round connector ECT sensor used by the ECM in early Fiero and other GM cars is no longer available. The new sensor requires a new connector. This connector is included with Borg Warner packages but will need to be purchased separately with many others.

Ping.
Ping Who?
Ping I just knocked a hole in your piston….

Engine Knock, Fuel Octane and other myths

Thing One: Never use higher Octane fuel than the engine needs to prevent knock.

I’m going to try to greatly simplify a very complex topic here. They write encyclopedias about this stuff. I’m going to try to keep it to a few pages.

What is Knock/Ping?

When the engine is running normally, the spark plug fires and the flame spreads evenly thru the cylinder. The mix burns evenly until consumed. When the engine Knocks or Pings it means the fuel was set off at the wrong time and/or the fuel was set off from multiple sources. Both conditions are bad for the motor and rob you of performance and fuel economy.

What causes it?

There are many things that can cause it. Most of them you can and should fix.
Here’s a list of common items. (In no particular order.)

• Over advanced ignition timing. (Very easy to do with mechanical distributors but still possible with electronic ignition.)
• Vacuum leaks or EGR problems. (These are way more common than people think.)
• Exhaust leaks. (Even small upstream leaks can screw up O2 sensor accuracy.)
• Wrong spark plugs or other bad ignition parts.
• Carbon buildup in cylinders. This alters engine compression and can create hot spots.
• Engine sensors dirty/bad or damaged sensor wiring. If a sensor is lying to the ECM the car will never run properly.
• Compression increased as a result of engine or head rebuild. (This can be intentional or a side effect.)

What is Fuel Octane Rating?

That number you see on the pump comes from a bunch of tests that determine how much the fuel helps resist engine knock. The higher the number the more it resists knock and it usually means the fuel is also less volatile. This last bit is the big rub… Less volatile fuel will often perform worse, not better as many people think. How much you may notice this depends on the specific engine in question. In any case, using more Octane than needed will not increase engine performance. Higher-octane fuel sells for more than regular fuel. Compared to most 87 Octane fuels, you pay 10-20 cents more per gallon for a product that costs them almost nothing more to make. That extra dollar or two per tank can add up really fast. Why spend it if you don’t have to… The carmakers all list the minimum Octane rating for fuels in the owner’s manuals. For most Fiero I’m pretty sure it’s 87 Octane. (I know the 87 owners manual lists 87 for both the 4 and 6 cylinder.) Oh, and the factory 2.8 has lower compression than the 4 cyl, so don’t go thinking bigger engine means more Octane. (2.8 is 8. something:1 while L4 is 9:1) Even motors with 100,000 miles or more can run the specified Octane if they are in good shape. Mine has over 150,000 miles and is running wonderfully on 87 Octane fuel. (Even WaWa fuel that is usually one of the lowest priced fuels around the region.) Note: Someone in the forums pointed out the European Octane ratings are higher than the U.S. numbers. Keep in mind other regions of the world use different methods and rules for grading fuel. While the European Octane number might be higher, that doesn’t mean they are automatically better than U.S. fuel at preventing knock.

Bending the rule, additives in Pump Fuel

All U.S. fuel is required by the EPA to have cleaning additives in it. Fuel meeting the minimum requirements is perfectly fine for most cars. Some fuel vendors promote their fuel based on the additive package. These additives won’t add power so much as restore or maintain it by removing carbon and dirt. These additives have contributed to confusion over octane ratings. These cleaning additives, which are unrelated to Octane rating, may help performance in some vehicles. This can be a function of brand, grade, or both. Some brands use the same additive package in all grades of fuel, while others put the “good stuff” only in higher grades. As an example, Texaco puts “Cleansystem3®” in all their fuel. Other brands may put their best additive package only in premium grades. What results you’ll get from any additive packages will depend greatly on the condition of your engine. None of them are likely to clean up a really dirty motor but they may help an engine expel minor carbon buildup and other dirt. Some no doubt do this better than others. Other than cost, it won’t hurt anything to shop fuels based on their additive package. If one product works better for you than something else that’s great. Otherwise don’t buy more than you need. To use Texaco again… Since they put Cleansystem3® in all grades, you’d still run the lowest Octane fuel the engine will take. If Texaco 87 Octane fuel works, their 89 and higher isn’t going to do anything but cost more. (Texaco is just a handy national brand for an example… I use a regional brand most of the time.)

The car knocks/pings…

We’re talking generally stock engines here. Even a regular rebuild should run on the OE octane or maybe one step higher. Obviously if you’ve done a big build up or super/turbo setup, you could need more octane. If a car that was built to run 87 Octane only runs on 90+, the engine may just be dirty or you could have mechanical problems. If the car knocks even on the highest Octane pump fuel you almost certainly have engine problems that need repair. These are some things I look for when an engine knocks. Triple check for vacuum leaks. Even a tiny leak can lean out a cylinder enough to cause knocking without tripping ECM errors. (You’d be surprised how easy it is to have a vacuum leak that only messes with one cylinder.) Check the cooling system very carefully. Knock/Ping can also be an early sign of overheating. Don’t assume the temperature gauge is correct. (Even if it is correct, don’t assume there are no cooling problems. A common problem here is a head gasket installed wrong. This can make some cylinders hot even if coolant temp reads ok on the gauge.) Check timing on distributor motors very carefully. The difference between knocking and not can be just a couple degrees of advance. (Defective or improperly configured Mechanical Distributors are great for this.) Use OE EGR valves (GM, AC Delco, Motorcraft, etc.) whenever possible. If you must use a “universal” style valve, make sure it’s a good brand. A crappy EGR valve can really screw up an engine. (I have seen aftermarket valves die in as little as a year.) Is the engine suffering carbon buildup? You might want to try one of the carbon removal processes. Carbon buildup can be the result of past fuel system problems and other things. It usually won’t go away without help. Is the engine sucking oil? This can both alter the octane of the mix inside the engine and cause carbon buildup. It’s probably time to rebuild some or all this engine or find another. Higher Octane fuel or carbon removal is at best a temporary fix. 87-88 Fiero L4 motors with DIS may need a different PROM in the ECM. GM had an update to tweak ignition timing a bit. (The new PROM numbers are in DIS notes. This kind of stuff is common with ECM/PCM controlled motors.) This should be considered ONLY AFTER all other mechanical items are checked out.

An example

Awhile back, my car started knocking under certain load conditions. (87SC L4 w/ DIS) I’d also lost some fuel economy. This went on for weeks and since the problem wasn’t consistent, it was really a pain to find. It did it even on 90+ Octane fuel. (Since it hadn’t done this previously, I didn’t think the PROM update would help.) In searching for a vacuum leak, I took off the EGR to see if maybe the middle of the gasket had partly blown out. (A common problem with this type of EGR setup.) The EGR wasn’t that old, and like many aftermarket units not easy to test. Since it wasn’t very old I didn’t really expect it to be bad but just out of habit I checked to see if the pintle was moving ok while it was off. It wasn’t moving at all… It turned out that the 2-year-old aftermarket EGR valve had failed totally. It had jammed in such a way as to not open and still leak slightly. (It never set any kind of code in the ECM during all this.) The spring in the top had actually broken and you could hear it rattling around when shaken. Replacing the EGR with a good used GM valve solved both the knock problem and cranked fuel economy back up to 26 mpg even in really crappy traffic. (The EGR gasket cost about a dollar.) The lesson, yet again, is never to assume recently installed parts are good.

Fuel additives

Octane Boosters and Cleaners

Octane boosting additives don’t help much except maybe for when you have a modified/race engine and can’t find suitable fuel at the pump. A stock vehicle that won’t run on pump gas has something wrong. Octane booster products, like higher Octane fuels, usually will not increase performance. How much, if anything, a cleaning product does will depend greatly on how messed up the engine is. Don’t expect any miracles from most of them. Even professional cleaning products may not remove heavy buildup. Some add in Octane boosters and cleaning products may actually damage the older styles of port fuel injectors used by GM and some others. In the older injectors, used thru the late 90’s, the solenoid coil is exposed to the fuel. (This helps cool the coil.) Most products are probably ok but make sure they are used as directed on the container. Mix them stronger than directed and they might eat your injectors. (The newer GM injectors are redesigned and do not expose the coil to the fuel just because of this problem.)

I’ve heard fuel changes by season….

Yes fuel does change by season and it also changes by city and region. This double whammy can make buying fuel quite confusing. If you suddenly drop or gain 2-4 MPG, you might be a victim of Reformulated or Oxygenated fuel. In some vehicles these fuels may also induce knock/ping that forces you to a higher, more expensive, grade of fuel. What many people call Winter Gas is defined as Oxygenated or Reformulated Gas (RFG) depending on where you live. They are supposed to reduce air pollution. These fuels contain MTBE and other chemicals to increase the oxygen content of the fuel. They cost more, often cause odd problems, bite performance, and you get less MPG. There is little you can do about the problems caused by RFG and Oxygenated fuels. On HEI engines, try retarding the timing very slightly if you have ping/knock.

Acceptable Alcohol Fuel Content

Methyl Tertiary-Butyl Ether
Fuel containing Methyl Tertiary-Butyl Ether (MTBE) may be used, providing there is no more than 15% alcohol by volume. MTBE is under investigation in many places. Some states are likely to ban it in future. MTBE is intended to reduce air pollution but has been shown to be a serious problem when it gets in the water. Small amounts of MTBE can pollute large amounts of water and the stuff is hard to filter from drinking water.

Ethanol
Fuel containing ethanol (ethyl) or grain alcohol may be used, providing there is no more than 10% ethanol alcohol by volume. Ethanol plays a roll in Octane rating and pollution control. Its presence in motor fuels is likely to increase greatly as MTBE (Methyl Tertiary Butyl Ether) is phased out in many regions. Higher concentrations of Ethanol will alter the fuel beyond what the ECM/PCM can deal with, and may be too strong for some fuel system parts to handle. Pre-computer engines may need considerable carburetor and distributor adjustments to run right.

Methanol
GM recommends against any methanol use. It can damage the fuel system parts. (Nearly all carmakers say stay away from methanol even now.) “Dry” gas typically contains Methanol but not enough to hurt anything. Fuel containing methanol (methyl) or wood alcohol may be used, providing there is no more than 5% methanol by volume. Use of fuel (gasohol) that contains more than 5% methanol can corrode metal fuel system components and damage plastic and rubber parts.

by: Gary Ohst

>> I was hoping anyone could tell me what the difference is between the SD valve cover and the stock 2.5. Specifically is the bolt pattern the same and is there room for needle bearing rockers?<<

The bolt pattern is the same for all years. There is plenty of room for valve train mods. That cover is too tall to fit under the stock air cleaner intake housing. There are no provisions for a PVC valve port. It would require some mods to fit on a production motor with all emission control hooked up.

>> Well I finally found the supplier of the Super Duty Block online. Check it out at: http://www.gtsonline.com/krp/prod1.htm<<

Doug Thompson took over production of the SD block when GM dropped the ball. You should know that the cost is prohibitive at around $2,500 each. They are actually stronger than the original SD block and can accept a variety of cylinder heads. Buying a complete used SD race motor and de-tuning it for street use would be far more economical. Aries pistons makes an aluminum SD block for around $4,000 if you think $2,500 is bad. By comparison, the last new SD iron block I bought from GM cost $850.

>>I wonder if the block, crank, cam and connecting rods will work with stock type pistons and a stock cylinder head?<<

Most parts interchange, but… The SD4 cranks have 2.10 rod journals (SBC). The stock crank is 2.00. If you run a SD crank you need to change the rods. The rod length and crank stroke influence the compression height spec of the piston. If you increase stroke or change rod length, new pistons are required. All SD heads use 1/2 head bolts. All production heads use 11mm. You need to drill and re-tap production blocks if you run a SD head. SD blocks already have 1/2 head bolt holes. SD blocks also have all the stock mounting bosses, so you can bolt up all the stock accessories if you want.

>>I know this sounds like a “halfway” job but my reasoning is simple, use these components with about 9:1 or 10:1 compression, at about 2.7-3.0L, do a mild porting job on the stock head, install lighter valves and stronger valve springs with better rocker arms (rollers maybe).<<

The production “swirl-port” intake ports are restrictive. The first thing you should do is hog out the stock intake ports or use a SD head. The next weak link is the crank. The S10 truck block and 1988 crank with center oil pump drive gear are the strongest stock parts. If you add displacement with a larger stroke SD crank, you are into a SD head to match increased flow requirements. An SD head on a production block is a far better match than a production head on an SD block.

>>I have looked into various options for my engine rebuild. A local machinist I visited, who builds racing motors said that the problem with the Duke is not necessarily the bottom end but the head. It is restricted, thin, and prone to cracking.<<

Yes. They are OK for performance street use if you open up the intake port and check for cracks.

>> So, maybe the way to go for a half and half is to leave the bottom end basically as it is and go for the upper…….<<

The bottom end is good for 150+- HP. Maybe 180 with the right components (88 crank/S10 block). The duty cycle goes down as power output goes up. Don’t expected it to last like a 100 HP production motor.

>>I need facts here, not rumours or speculation. What is the problem with the Iron Duke regarding the 5000rpm ABSOLUTE rev limit I have heard mentioned.<<

It was a low-cost, entry-level power plant for a lot of GM cars, not just Pontiac Fieros. The crank was made as light as possible for throttle response and fuel economy. It was designed for low performance cars and low performance driving. The stock crank is cast and weighs 30-35 lbs. The Super Duty counterpart is forged 4340 and weighs 50 lbs. The SD motors started to blow up at about 9,200 RPM according to Vanderly. These were under controlled dyno room conditions. Don’t know of hard data on production crank limits, but sometimes they flex and cause rod bearing failure before they break. If GM “rated” it at 5,000, it can go higher. Just like the Getrag 5-speed is “rated” at 200 ft lbs torque, but handles more than that. You are cutting into life expectancy when these guidelines are exceeded. GM has warranty concerns in mind when they “rate” parts.

>>Is there an inherent problem with the crank and bearings? The block appears to have five well supported main bearings (even if the main caps are not exactly “beefy”). The connecting rods are reasonably long so they should not suffer from angularity problems. With a good forged crank and good quality connecting rods (tested so as not to be flawed as many of the early ones were) will this engine hold together.<<

There is nothing wrong with the design. It was just optimized for economy and not performance. Of the bazillion 2.5 liter motors made, how many saw performance driving?. If you were GM, how strong would you have made the production crank? A forged crank supports over 200 HP. The problem is that while they are out there, they are near impossible to find these days. Only option is a billet crank from SCAT for $1,800.

>>Are people making to big a deal about this engine being weak because Pontiac ran the SD program to build a racing engine and made the stocker look inadequate or is there real cause for concern.<<

Because it was designed as light as possible on purpose, it runs into performance limits sooner than other motors. The same rules apply to other motors, more power and higher rpm equals stronger components. The SD program came about because GM knew they could not get where they wanted to go modifying production hardware. 150 hp is not a bad goal for four cylinders. How many eight cylinder SBCs do you know of making 300+ HP without upgraded internal components? The difference is there is a sliding scale of performance hardware for the SBC. The Iron Duke is black or white, SD or not.

>> Thank you very much, you have cleared up many of the unanswered questions on the 2.5. If I am reading you correctly, a good 2.5 block with no cracks, properly cleaned up but not overbored, combined with a good stock crank and good quality connecting rods. (I guess an 88 crank will not fit the earlier block, an 84)<<

Yes, the 88 crank will fit. The extra mass of the oil pump drive gear adds strength to the unit, but fits in all blocks. The major dimensions are all the same. Just be sure to use a 84-87 cam with the oil pump drive gear. The 1988 cam has no distributor or oil pump drive gears.

>> A cam designed for better mid range power (2000 to 4000 rpm) a porting job on the stock head (check for cracks first, don’t remove too much material), an exhaust header and a holley intake (if you can find one) or a stock intake with port matching. Combine with a free flow exhaust system and the stock electronics would I be reaching 120hp (with a 5000rpm redline)?<<

Porting the head is most important. In the area under the intake valve in particular. Holly TBI & manifold will not add much. Stock intake manifold/TBI flows enough. You may need a higher pressure fuel pump and adjustable regulator. Use more fuel pressure to adjust for VE improvements in the engine. That saves messing with the ECM fuel maps.

>>Would I have a strong running motor capable of hauling the tall 3.32 ratio four speed at a relaxed highway speed with some power left for passing, and decent reliability?<<

It is harder to get more torque at the same rpm than it is to get more hp at higher rpms. If you want a lugger, then a stroked SD crank may be what you want. 125 HP will work on stock bottom end components in rebuilt condition, but peak HP will be at higher rpm than stock.

>>I was on the MSD ignition website today and found that they have a new super duty billet aluminum distributor. The description mixes Iron Duke with SD. Are distributors interchageable?<<

Nope. It’s a “dumb” system that can’t interface with the variable timing feature of the stock ECM. It’s just has a mag pick-up that matches the standard MSD modules. Nice hardware, but only necessary for higher rpm use. Just upgrade the coil on the stock ignition as the first step. Unless you increase compression ratio or spin higher rpm, the stock system design is fine. Money is better spent elsewhere.

If they were to say it is “compatible”, you should be suspect. Since they say it only works with their module, you pretty much know for sure there is no way it will interface direct.

>>This distributor is designed to be used with their ignition controller (such as the #6). I have seen other cars with aftermarket ignitions. I understand the principle of multiple spark and cylinder effects. Could not get a straight answer about emissions control/ECM/TBI etc…… How does installing one of these affect the computer control of the car?<<

It does not interface directly. See above comments.

I am not a big fan of MSD, but their marine grade stuff may be Ok. My street driven beater car uses the stock system w/upgraded coil. No reliability problems, plus it’s emission legal that way.

I do run a simple Adrenaline CD system on another car rated at 180mJ (mil joules) per spark. If you look into it, that’s a lot of spark energy for a single spark system. The mJ spec is most important, but often never published by ignition peddlers… I wonder why?? Racer Wholesale used to sell these systems a few years ago. The Adrenaline brand was nice stuff with mil-spec components, but I don’t think they sell direct under their own name anymore. The trend is to get rid of the distributor, get rid of the spark plug cables, and now to focus on a better spark event. For a peek into the future of automotive ignition systems, check out the Adrenaline web page. Probably a few more years before these new systems become cost effective and a mass marketer picks up the design.

A 2.5 liter, 3 inch stroke 1988 production crank (left) next to a 3.0 liter, 3.625 stroke SD crank (right) so you can see the significant differences.

Variations of the 2.5L ohv GM four cylinder engine.

There are several variations on the 2.5L engine used in GM models. Before using a non-Fiero block as an engine replacement check out the following list.

Stay away from the oddball FWD only VIN U motor, too many parts are different compared to all other 2.5 motors. It was used only in FWD N-cars, Grand Am, Calais, etc. Crank thrust bearing and cylinder head bolt pattern are a few (see below). The VIN R (Fiero included) motors were used in both larger FWD cars (X and A body cars) and RWD applications with no special mods.

The S-10 truck block is good because it has solid main webs like the SD block. It is cast from average grade iron though, where as, the SD block uses 40,000 psi high nickel iron. The SD blocks come drilled for a starter mount on both sides.

The Vin E 2.5 liter truck motor was used in both Astro/Safari vans and the S-10/S-15 trucks. I think the later model 1991+ VIN A was only used in the pick-up trucks. The pick-up trucks have the starter on the right and the vans have it on the left (fiero side). Starter location can be changed

Here are some general VIN notes regarding the various 2.5 liter motors:

Vin V 1977-1980 Carb non cross-flow head (intake & exhaust manifold on same side)
Vin 1 1978-1979 Carb non cross-flow head
Vin 9 1979 Carb non cross-flow head
Vin F 1980-1983 Carb export only
Vin 5 1982-1983 Carb cross-flow heads from 1982 on
Vin 2 1982-1986 TBI Thrust brg length 1.009, Head bolt spacing 3.75
Vin R 1982-1992 TBI FWD/RWD/Fiero Thrust brg length 1.009, Head bolt spacing 3.75
Vin U 1985-1991 TBI N-car FWD Only Thrust brg length 0.940, Head bolt spacing 3.67
Vin E 1985-1991 TBI S-10, Astro Van Thrust brg length 1.009, Head bolt spacing 3.75
Vin A 1991-1993 TBI S-10 Thrust brg length 1.009, Head bolt spacing 3.75

The VIN E and A truck motors were also used in postal vehicles. That’s right, the mailman has a better block than you do

SEEK ADVICE FROM ONE WHO KNOWS HOW TO CURE A FAILING FIERO

POWER SECRETS FOR THE 4 CYLINDER FIERO

by S. J. Wynman

Most Fiero owners have 4 cylinder engines to power their cars. It appears no one has ever cared to have any real performance enhancement for these Fieros – well, your time has come! Now you can read about some methods to improve the overall engine performance of the stock Fiero 4 cylinder motor. This article is divided up into several topics:

1. Throttle body enhancements
2. Port Matching
3. Octane Tuning
4. Decarbonizing
5. Valve Guide Sealing
6. Increasing the Redline
7. Harmonic Balancer usage
8. Performance Build Up Parts List

Not all of the recommendations will apply to every year 4 cylinder Fiero. The first thing you must realize are the differences between the various 4 cylinder motors GM installed in the Fiero. The Table below summarizes the differences as they pertain to the article:

THROTTLE BODY ENHANCEMENTS
Back in the mid-1980’s HOLLEY felt they had a quick answer to the lack luster performance offered in all GM 2.5 Liter motors. They actually hit on something good, but it appears the idea was not an original one. GM used a performance Throttle Body Injection (TBI) unit on one of the original 1984 INDY Pace cars. GM later provided HOLLEY one of the prototype units and HOLLEY mass-produced them. Not only was the throttle body bore increased from 1.68″ to 2.00″, but the single injector output was increased to make use of the increased air flow. Although the result was impressive, HOLLEY wanted even more. They developed their own intake manifold, which had a larger intake runners, and TBI mounting bore to accommodate the larger throttle body bore. As a result, the combination proved to be excellent. This TBI can even bolt onto the stock 1984 through 1986 intake manifold. HOLLEY provides an adaptor gasket to allow the new TBI to bolt onto the old manifold. A few years ago HOLLEY discontinued their intake manifold, but you can still realize many of the HOLLEY intake manifold benefits. What you should do is machine out the opening in your present intake manifold. Do not open it up to the full two inches as this will probably interfere with the existing EGR passages. Use your judgement as to how much material can be removed. You can use the 2″ HOLLEY gasket as a guide. Scribe this diameter onto the intake manifold. Stuff the intake hole with moist rags to help catch the aluminum which is being removed from the intake manifold.

If you own a 1987/88 Fiero, you will need to fabricate an adaptor plate. GM totally changed the design of the TBI and intake manifold. You cannot use an earlier design intake manifold as the head on the 1987/88 has also changed. The earlier intakes will not bolt up to the newer head. All this means that a simple adaptor plate will have to be fabricated allowing the old bolt pattern of the HOLLEY TBI to be mounted onto the new GM designed intake manifold. Use a 1/4″ aluminum plate along with a new 1987/88 TBI intake gasket. Angled screws must be used to maintain a low adaptor plate height. Remember, you must still open up the TBI bore on your intake manifold. If you are lucky enough to find one, use a HOLLEY intake manifold (except on 1987-88).

PORT MATCHING
As a simplistc example, an engine can be seen as an air pump. The more air the engine pumps. the more power it develops. In order to increase air flow, any obstructions must be removed the air flow path. The first and most obvious obstruction in the 4 cylinder Fiero is in the exhaust system. When the muffler and catalytic converter are replaced with high flow units, and perhaps headers are installed (although they are not really a big advantage here), it is time to look at the intake system. The easiest improvement is to replace the air filter with a K&N Air Filter. The next step was previously discussed in the topic entitled Throttle Body Enhancements.

Once this has been completed, it is time to go inside the engine. This brings us to another 2.5 Liter engine improvement which is to perform port matching. The only safe way to perform this improvement is to remove the intake manifold, exhaust manifolds, and the head from the Fiero. Otherwise, dirt and metal particles will enter the cylinders and drastically shorten the life of the engine.

This is a process where the gasket, between the intake manifold and the head, are used as a template for both the intake manifold and the intake ports on the head. There is enough metal on the desired work surfaces so the port matching can be accomplished safely. The head should be off the engine and all of the valve train should be removed. After the work is completed, the heads should be thoroughly rinsed and cleaned. Follow the GM or Haynes shop manual for the removal of these components.

HEADS. The intake ports are first painted with a blue dye. The intake to the head gasket is then laid on the heads intake side using a manifold bolt as an alignment device. Use an Exacto knife to scribe the intake passages of the gasket onto the head. You will notice the port openings of the gasket are larger than the intake port opening of the head. Now use a 3/8″ flame shaped carbide rotary file installed in a die grinder (capable of 20,000+ RPM speeds) to expand the intake passages of the head. Only enter the head by 1″. Going beyond this point may result in head, valve, or valve guide damage unless you have previous experience in the porting and polishing process. Use your fingers as a guide to determine how the work is progressing. The newly improved openings should have a smooth transition into the head.

The exhaust side of the heads can use the same improvement. The exhaust side will require substantially less work because the ports are closer in size to the exhaust manifold gasket ports. Use the technique above to port match the exhaust ports.

INTAKE MANIFOLD. The same gaskets used to improve the intake ports on the head are now used to open up the intake manifold to head ports. This is the most restrictive area in the intake tract. Make sure the holes are open and clean. Use brake cleaner and Gum Out to clean the passages.

Later, when installing the intake manifold, use FELPRO BLUE as a gasket sealant on both sides of the gaskets and follow the shop manual torque sequence for tightening the intake to head bolts.

The intake manifold was factory painted with a silver paint on most 4 cylinder Fieros.

EXHAUST MANIFOLDS. The exhaust manifold is made of tubular stainless steel. The manifold is basically a four into one header. Believe it or not, this manifold is relatively free flowing. Concentrate your efforts in the area where the “header” connects to the rest of the exhaust. Do not remove more than the obstructions, as the manifolds are relatively thin walled. Also, do not trim or port match the mounting flange of the ports themselves, as this is where the welds are, which hold the mounting flanges onto the stainless steel pipe. You will end up cutting through the welds which hold the stainless steel tubing to the mounting flanges. Clean out all of the metal particles, otherwise they will end up either in your engine or in the catalytic converter.

The exhaust manifold was not factory painted.

OCTANE TUNING
One of the gasolines octane rating characteristics is its resistance to pre-ignition. The higher the octane, the higher the resistance to pre-ignition. As an example, 93 octane gasoline is more resistant to pre-ignition than 87 octane gasoline.

To a limit and as a basic rule of thumb, the more your engine timing is advanced, the more power it will make. The two draw backs to this theory are that more advanced ignition timing settings will tend to promote pre-ignition and also increase exhaust emissions.

The secret here is to use high octane gasoline at all times. Once you have purged the lower octane gas from your tank, by constantly diluting it with higher octane gasoline, you can reset the timing of your Fiero. This trick is limited to 1984 through 1986 2.5 Liter motors as the timing is totally ECM controlled on the 1987/88 4 cylinder Fieros. You should follow the Fiero shop manual for the details of this procedure, however the following are abbreviated steps on how to perform this task. This is done with a timing light and 13 mm socket. Run the engine warm and then loosen the distributor. Move the distributor to increase initial base timing. The normal base timing is 8 degrees BTDC. Now advance the timing to 10 or 11 degrees BTDC and tighten up the distributor. By doing this you are resetting the initial timing of the engine. The ECM cannot determine the base timing and assumes you have set the initial timing to 8 degrees BTDC The ECM now adds its own calculated advance curve to this new base timing. This means the 10 or 11 degree advance you have set will remain in place throughout the entire RPM range.

Now you have must test the new timing settings. In 95% of the cases the new timing will not be a problem. For the other 5%, the problem is with the motor. High carbon deposits and poor quality gasolines are just two examples. With the side windows open, accelerate and listen for a rattling or knocking noise. Hopefully you will not hear either sound, meaning everything is alright. However, if you hear these sounds, back off the timing by 1 degree and repeat the test. Repeat this step until no strange noises are heard.

The advantages you will experience by completing this task are more power and better fuel economy. The down side are increased exhaust emissions. This is the reason why GM limited the Fieros 2.5 Liter timing to B degrees BTDC. It is for this reason you should advance the timing only if your Fiero is to be used in off road applications.

DECARBONIZING
Carbon deposits have always been a fact of life with the internal combustion engine. Unfortunately, the introduction of fuel injected engines during the mid 1960’s had introduced a new set of problems. The problems included new areas of carbon deposits. Carbon deposits accumulate everywhere in your engine. The only way to slow down this process is to use premium name brand gasoline. According to a spokesman from MOBIL, a detergent with anti-carbon properties is placed in all grades of gasoline sold by MOBIL. The only difference is the concentration of this detergent varies with the grade of gasoline. The premium grades contain the highest levels of the detergent additive.

Carbon deposits form in quantity in two areas of the 2.5 Liter Fiero engine, the intake tract and around the intake valves.

The intake tract can be completely clean only through disassembly and the use of a wire brush. Aside from doing this you can clean another area, which immediately affects performance, and is accessible with the engine fully assembled and also still being in the Fiero. The others are in the throttle body. Excessive carbon can prevent the throttle plates from closing completely or even blocking some of the vacuum passages. The throttle plate can become stuck (open or closed) and even end up setting some ECM codes. The air cleaner side is always nice and clean. As soon as you pull on the throttle cable to open the throttle plate everything is black. It is this black carbon which you must clean. This is accomplished with a brass tooth brush and several cans of Gum Out Carburetor Cleaner. First place a small clean damp rag just past the throttle plates. This will prevent debris and excessive amounts of Gum Out from entering the engine. Soak the blackened area with Gum Out and then use the brass brush to loosen it. Remove the debris with a clean rag. Spend extra time cleaning behind the throttle plate, the throttle plate pivots, and the throttle body bore area where the throttle plate touches.

Carbon around the intake valves is a much more severe and difficult problem to correct. The problem arises when the cool gasoline leaves the fuel injector and hits the heated valve causing some microscopic deposits to be left behind. This problem is further compounded when the intake valve guide seals (two per intake valve, an Umbrella type and the standard “0″ Ring type) deteriorates which allows oil to build up on the valves, which can amount to an incredible build up. This can actually block most of the air flow into the cylinders. This results in a choked engine which refuses to perform. Some companies sell products which claim to remove this carbon build up, but I have not experienced ant to perform as claimed. The only efficient way to remove this intake valve carbon build up is to remove the intake valves from the heads and either replace them, or clean them with a sharp chisel and a wire wheel. This procedure requires removing the heads from the Fiero.

VALVE GUIDE SEALING
Virtually all engines contain valve guide seals. The purpose of the seals are to prevent oil from entering the valve bowl area and either getting burned (intake) or leaving as a cloud of smoke (exhaust). Heat and time take their toll on the seals. The result is carbon depositing on the intake valves developing quicker (see above), resulting in the Fiero smoking after sitting still for sometime.

The valve guide seals can be replaced without removing the heads from the engine. As a quick overview the following must be performed. Follow the shop manual for detailed procedures on each of the following over viewed steps:

1. Remove the valve covers
2. Remove all four spark plugs
3. Remove all eight rocker arms
4. Install a compressed air adaptor into the spark plug hole and apply compressed air. This will hold up both intake and exhaust valves for the cylinder being worked on.
5. Using one of the rocker arm retaining nuts, and a lever type on-car spring compressor, depress the top of the valve retainer, With needle nose pliers remove the two valve stem keys (keepers). Release pressure on the valve spring, then remove the retainer and valve spring. The compressed air will hold up the valve, Remove the old “0″ Ring seal (both the intake and exhaust valve have this seal), and wiper seal if you are working on the intake valve, Install the new seal(s) and reverse the process to replace the valve keys.
6. Repeat steps (4) and (5) above for the other 7 valves.
7. Re-assemble the remaining components of the motor per the shop manual.

INCREASING THE EFFECTIVE REDLINE
The redline, or maximum operating RPM of the 2.5 Liter engine is 5000 RPM. Most stock four cylinder engines have a hard time finding the high side of 4000 RPM. Many engine parts can limit the maximum RPM of an engine.

A large step can be realized in achieving that 5000 RPM redline in the 1984 through 1986 Fieros. This is done by replacing the ignition coil. GM makes some nice ignition parts, but fell short with the coil. The answer: Bolt on an ACCEL, or other brand of high performance coil onto the rear trunk sheet metal, near the original stock coil location. With a coil change, a free flowing catalytic convertor, and a new TBI alone, you will really wake up the little motor.

HARMONIC BALANCER USAGE
A harmonic balancer absorbs the torsion vibrations which occur within the crank shaft. These vibrations are caused as each cylinder fires and part of that “power pulse” is sent to the crank shaft, in a direction which does not contribute to the power being output to the flywheel. Having a harmonic balancer does not eliminate the pulses, but it does give them a place to go. This will contribute to longer crank shaft and timing gear life. GM introduced a harmonic balancer for the 1987/88 Fiero 2.5 Liter motor. The part number is 10101369. Unfortunately, GM did not think about the earlier Fieros models.

BUILDING UP THE FIERO 2.5 LITER MOTOR
GM developed a nice 2.5 Liter engine program. This program is called the Super Duty Four Cylinder. Once this motor is built up correctly, it will give a 1996 Corvette a run for its money. The bad news is that just about every piece of this motor is race ready, and very expensive. A completely assembled motor will run about $7000.00. As you can see, this is a little on the high side. Do not give up hope or even your stock four cylinder. if you follow all of the previous suggestions, your stock 2.5 Liter will be good for about 110 to 115 HP. Considering the stock motor puts out about 94 HP this is not too bad. If you want more, then a complete rebuild is necessary. Standard Blueprinting practices are recommended, along with the following parts:

1. Pistons – TRW piston part number 248SF-SO, TRW ring part number is T8370-30. This is a forged 0.030 oversized piston. I do not recommend an over bore larger then this as the block is not to strong or thick in the cylinder area. Make sure a deck plate is used when boring and honing the cylinders. The compression ration will increase to about 9.1:1 where stock is approximately 8.4:1. I strongly recommend the use of the previously described improvements if you decide on these pistons. These pistons will fit in the 1984 through 1988 motors.
2. CAM Shaft – TRW TP-209, Intake Lift = 0.409″, Exhaust lift = 0.516, Duration lIE = 204~/2 140. This is a nice improvement over stock and which will not require head work for the spring perches. The stock ECM will also work with this cam shaft. I strongly recommend the use of the previously described improvements if you decide on this cam shaft. This cam is a direct bolt in for the 1984/85 motor. You can use it in the 1986 to 1988 motors if you use conventional lifters in place of the roller lifters. You will also have to use the 1984/85 push rods in the later motors if you use this cam shaft.
3. Timing Gears – Cloyes makes a nice all steel set. GM has improved their own timing gears which can be ordered under part number 10101790. This gear set will fit the 1984 through 1988 motors.
4. Valve Springs – TRW part number VS1 100, using retainers SR363. These parts can be used only in the 1984/85 motor. Use the stock springs with the 1986/88 motor.
5. Oil Pump – TRW High Volume part number 50132. This oil pump can only be used only in the 1984 to 1986 motors. The 1987/88 motors use a gyrator type pump which is part of the balancer assembly.
6. Use brand new GM Head, Connecting Rod, and Main Bearing Cap Bolts. Follow the latest Torque-to-Yield Bolt specifications.
7. Replace the catalytic convertor with a high flow ACCEL unit.
8. If the oxygen sensor is 2 years old or older, it should be replaced. The accuracy decreases the range of forcing the engine to run lean.

Balance the reciprocating crank shaft mass to within + 0.5 gram. This includes the crank shaft, pistons, rods, rings, bearings, front hub, and flywheel. This will remove much of the engine vibration characteristics and provide a slight increase in power.

Increase the fuel pressure on the HOLLEY TBI unit (it is adjustable) to 15 pounds.

After the stock or aftermarket header, replace the stock exhaust with a 2 1/4″ stainless steel unit such as the one sold by the Fiero Store. This removes the stock restrictive muffler and replaces it with resonator tips. The sound is a little louder, but it does sound nice.

This is about as good as you can expect with the stock block, crank, and head. You can expect the engine to produce 120 to 130 HP if all of these modifications are made.

We can debate this until the cows come home….. but unless you go the SD route you ain’t gonna make a significant difference in the overall performance of street driven Dukes with add-ons (been there – done that). If you are successful in cranking out significantly more HP, the lower end will not last much longer. Experience has taught me (and others) that when you start consistently pushing a Duke over 5,000 rpm it is going to self destruct. It ain’t a matter of “If”, it is when. Do you ever wonder why the early 2.5 turbo kits died off so quickly? It wasn’t the introduction of the V6 – they were a prescription for a broken crank or pitched rod.

Still, there are some things you can do to a Duke to improve performance that are simple, cheap, don’t compromise reliability and should be done anyway. Sadly, they are often overlooked or ignored. It has been at least 5-6 years since I put this on the list, but it is still valid. If you have previously done these, GREAT! If not, try it – you’ll like it. (You will also get better gas mileage)

1. Replace the fuel filter. Do this every other oil change or 6,000 miles. Restricted fuel filters lower fuel pressure. Lower fuel pressure translates to a drop in performance. This is often overlooked and is true for the 2.8 as well.
2. If you still have the stock converter, replace it with a new high flow unit. Gains will be noticeable as the original L4 brick catalyst is very restrictive.
3. Drop in a K&N air filter – or at least a new paper one.
4. Pop in a new oxygen sensor
5. Change to synthetic oil
6. On 84-86 Dukes, bolt on a performance coil and a new set of lower resistance plug wires.
7. Install a fresh set of spark plugs – NEVER put Bosch Platinum plugs in a DIS car (87 & 88) If you have not added a higher voltage coil and wires, close the gap .005 less than specified. “Trick” plugs (Splitfire, etc.) are OK, but a waste of money as far as performance gains. A set of new steel electrode AC plugs will do just fine.
8. Bolt up the dual outlet muffler and pipes from a 85-87 V6. There are tons in the junk yard for little or noting. Don’t expect a great performance improvement, even if there is one less chamber in the V6 muffler, but it looks and sounds better.
9. Run maximum allowable air pressure in your tires and avoid those tall fat ones – especially on the back. They can change your effective gearing and reduce HP at the point where the rubber meets the road.
10. Try a 160 or 180 degree thermostat. It may take longer for the car to go into closed loop but Dukes seem to run better in the 180-200 degree water temp range. Add a manual fan switch so you can cut it on at will, don’t wait for the fan temp switch to do it or the water temp will soar even with a low temp thermostat.
11. Be sure no calipers are dragging – especially the rear EM brake.
12. Run a batch of carbon removal and top engine cleaner through (Ed Parks sells this and the stuff really works!).
13. For quicker off-on throttle response, disconnect and plug the vacuum hose to the EGR valve. May have to move to mid grade 89 octane gas for this. Also increases emissions. Will not give more overall HP – only quicker throttle response. On a 2.5 the ECM doesn’t know this has been done. (Note this may cause emmissions problems. I.C.)
14. Give the car a wash and wax, clean cars always run better – you know, less wind drag over a slick surface thing.

If you have not done these low cost items, you will be amazed in how much better your Duke will run. Then, if you gotta learn the hard way (like I did) go ahead and face the wind and pull those bills out of your pocket for your visit to the johnny house…… or you could just donate them to me.

No way (short of the SD-4 – see http://fierozone.com and click on “Blast From the Past” for SD 4 articles) will you get the HP gains you want with the other higher cost add on mods for the L4. Port matching and larger TB’s won’t hurt – but they won’t help much either unless you go the whole nine yards (heads, headers, cam, etc.).

One of the most important things you have to be aware of when trying to improve the performance of the Iron Duke is the well-known fact that it has a weak block. Remember that this engine was designed from the ground up to be as fuel efficient as possible. High performance was never a major design goal of the engine. Therefore, strength and the ability to accommodate higher performance was sacrificed in the name of weight reduction. Low cost was another design goal, so more aggressive steps to increase efficiency such as porting and polishing were overlooked. It is in areas such as these that I believe the performance can be gained; not by pulling more power out of the engine, but rather removing obstructions or restrictions that are consuming the power that the engine already has. I believe that if you are going to be successful, you have to accept the concept of ‘power through efficiency’. Any other approach is going to result in a blown engine. I can almost personally guarantee it.

That said, the next most important thought you should keep in mind is that of properly matching all the parts during the rebuild. An engine with a well-matched set of conservative parts will usually provide better results than an engine full of high performance parts that are not matched. Take a good long look at your driving habits and your expectations for this vehicle. If the car has a manual transmission, what RPM ranges do you normally shift at? What gear do you prefer to use when passing people? What speed are you normally driving at when you decide it’s time to ‘get on it’? Is this a daily commuter or a weekend sportster? Take these thoughts into account before, during and after you start to rebuild the engine.

You also need to be realistic about your expectations. The Iron Duke is a great engine for efficiency and moderate to respectable performance. If you are looking for a truly significant jump in performance, say more that a 25% increase over factory rated HP; this is not your engine. By the time you pull that much HP out of the engine, you will have spent a small fortune and in all likelihood the engine will fail very quickly. This article is for those that have more time and patience than money and just want to have a reliable, efficient, smooth running little 4-banger that gives them reasonable performance when it is occasionally needed. If you are expecting more, go for a V6 or V8 conversion. The bang to buck ratio will be much better with a conversion approach and they are not as expensive as you might think.

If you are an experienced mechanic and are comfortable with choosing your parts, by all means do so. If you are a little foggy in this area, like myself, seek out the advice of an expert in your area. Most of these people are more than happy to share their knowledge with you, especially when they see that you have already given some thought to how you want the engine to perform and considered how your driving habits have played into your decision. If you don’t trust your mechanical skills at all, you can have a local outfit build the engine for you. Just make sure you pick a quality shop to do the work. If you have no fear of spinning wrenches, feel free to ask an expert for guidance on how to best match and assemble the right parts for your needs. They usually don’t mind being used as a resource because they know that you will have to have certain machine work (boring, milling, turning, etc.) done somewhere, and if they are helpful, they just might get your business.

The first step to building an engine is to select a camshaft that matches your performance expectations. This one part more than any other will determine the true nature of your new engine. Again, be realistic. If you try to put a full race cam in, you will have to take extreme measures to take advantage of it, by which time your will likely have exceeded the block’s capabilities. Once you have chosen the camshaft, you should build the rest of the engine around that. This will affect what type and compression of pistons you use; how you have the head milled and what type of valve springs you will use. It can affect what kind of exhaust system you install and what type of ignition products you buy. Based on the camshaft, you might choose to port and polish the head and intake manifold. You may opt for a three or five angle valve job. Of course, some of this may be a bit overboard, and if you choose a cam that HAS to have all of this, you’re probably being a bit aggressive. Again, consider a conversion instead of going overboard.

I was fortunate enough to have an engine designed for roller cams, which made having a new profile ground onto the original cam a viable possibility. Roller cams have far more success than standard tappet cams with longevity after being reground. This was certainly a good thing because there were not many aftermarket options for a new cam at the time. Kams, Inc. in Oklahoma City put a mild RV profile on the cam that adequately matched my driving style. It was certainly streetable; started easily even in winter; had a good mid-range power curve and respectable fuel economy at highway speeds. From there, I chose 9.5:1 compression pistons that would pull a little more power out of the fuel without inducing too much stress on the weak cylinder walls. I had a great local outfit named Buddy Rice do all of the machine work on the engine. They were the ones that helped me choose parts that would perform well with the camshaft profile I had selected. The block and head were both cleaned. Then, I had the centerline bore reestablished on both the camshaft and crankshaft bores. They also trued up the bores on the connecting rods. They milled the head and performed a 5-angle valve job, and then shimmed the valve springs to match them with the camshaft. The crankshaft journals were also turned, along with the mains that were ‘recentered’ to match the work done on the block. They looked at the idea of balancing the crankshaft, but ultimately decided against it because of its light weight and the fact that it was already fairly well balanced. While the engine was still at the shop, we carefully looked over all the parts for any signs of wear. Anything that showed any significant wear was replaced. Better to catch the problem now that to find it later after it fails.

With the block and head prepped, I took all the parts home and started putting the engine together. I didn’t do anything special while assembling the engine. I just made sure I was liberal with the engine assembly lube. I use this stuff on everything, not just the camshaft. I also made sure that I followed the torque specifications for everything; using several increments up to the final torque for anything over 25 ft/lbs. When working on the engine or suspension, I never tighten anything with an ordinary wrench. I always use a torque wrench to make sure I am not overtorquing something. I also do this to make sure that matching bolts on a part are torqued uniformly to prevent warping.

One note of caution; whenever you are not working on the engine, make certain to but a thick plastic trash bag over the engine and seal it airtight with tape. When I first started the engine, I had no oil pressure at all. After taking it back apart, I found that a wasp had built a mud nest in the oil pump that completely blocked the passageway to the oil filter. Fortunately, the liberal use of the assembly lube saved the engine from damage. The bag will also help protect the engine from dust and humidity.

At the time of this writing, this was the extent of the work done to the engine. Notice that the only higher than stock performance parts are a mild camshaft and slightly higher compression pistons. Everything else was just removing any possible sources of resistance, and making sure that each part could do its job in the best possible environment. The engine already performs extremely well. As time permits, I will port and polish a spare head and intake manifold from another engine. I will install them along with a new exhaust, headers, Holley’s Big Bore TBI and a good aftermarket coil. Some additional notes would be that I removed the restrictor plate underneath the TBI in the intake manifold; I use a cooler thermostat and coolant fan switch; and that I disconnected and capped the vacuum line to the EGR valve. If you choose to do the same, make sure you reconnect the EGR for one day every month and take the car for a long drive. That way, it will work when it is time to get your inspection. Something else to keep in mind is that I personally would probably never go this far with another Iron Duke. When I started, I did not know about the ease and tiny cost of certain V6 conversions. Also, I was fortunate enough to have a rare engine. This is a 2.5R engine, not the normal 2.5L. GM ran the numbers on it and describes my engine as an ‘84 Fiero Second Design’ engine. They swear it is definitely for the ‘84 Fiero even though it has roller lifters, which the ’84s are not supposed to have. I’m certain this plays a part in the better performance, and in this case, makes the extra effort worth it. I have a 4 banger that performs very close to many of the V6 Fieros, yet retained the efficiency of the 4 cylinder and did not sacrifice reliability or life in the process. I paid a whopping $200 for the car and spent around $1,000 rebuilding the engine. As long as I take care of it, this little baby will last forever.

The Pontiac Fiero has been available with three differently geared Muncie 4 speeds, an Isuzu 5 speed and the Muncie Getrag 5 speed. The 3 speed model 125 is the automatic transmission (with lock up torque converter). Here is a brief run down of what was available and what it means.

Transmission: Simple working definition, a device for transmitting engine power to the the final drive (and then on to the wheels).

Transmission lore is a mixture of fact and myth. Let us explore some of these points with an eye to the Fiero. (Note: emphasis on issues of importance to potential engine swappers)

Automatics, in the case of the Fiero a TH125 three speed with torque converter lockup. A reliable transmission, if not exactly an exciting one. The automatic is a good choice with V6 models, or sufficiently beefed up for a 3800 or V8 engine swap.

4 Speeds, again the four speeds are an excellent choice for the high torque, low rpm powerplants. A 1984 economy 4 speed (option MY8) would make a very good high speed cruiser with a Chevy V8, allowing decent fuel economy, relaxed cruising (about 2000rpm at 60mph) and plenty of performance because of the flat torque curve of the typical 305 or 350. The 3.65 ratio 4 speed used in the V6 (M17) would also prove a good choice giving better acceleration but a rather busy highway cruise and lower fuel economy, this transmission would be a better choice for a 3800 V6. The 4.10 4 speed (M19) is best left to the drag racers (or as an acceptable but less than ideal unit for the high RPM twin cam engines.). There is no real difference between the 4 and 5 speeds other than the fact that the 5 speed has more intermediate ratios which allows you to keep the engine in its powerband.

That’s it! As a matter of fact when Porsche built their first Turbo 911s they actually replaced their normal 5 speed with a beefed up 4 speed since they could build a very strong 4 speed which would be lighter than an equal 5 speed (Their normal 5 speed was not strong enough). They reasoned correctly that the increased torque of the turbo made the extra ratios unnecessary. Marketing however showed that people saw a 4 speed as being “low tech” so the 5 speed soon returned BUT ONLY BECAUSE PEOPLE WHO KNEW LITTLE ABOUT CARS DEMANDED IT. Just as a 5 speed V8 combination is unnecessary in a Fiero unless you plan on competitive road racing. This does not mean that a 4 speed is preferred over a 5 speed, just that if you have a perfectly good 4 speed you may not NEED a 5 speed unless you are racing.

5 Speeds, The Isuzu 5 speed attached to 85-88 4 cyl Fieros is not a good choice for a high torque swap, it is not strong enough. This transmission may cause problems because of weak cast alloy (pot metal) shift forks, which could break if abused especially at high rpms. Careful shifting can make these transmissions survive since it is the shift forks, and not the gears, which causes the problems. The gearing of the Isuzu transmissions seems to be a better compromise than the Getrags, but the reliability issue can cause some concern. This leaves the Getrag, although not perfect it is probably the best transmission used in the Fiero. It is strong enough for the high torque V8s and V6s but with the better ratio spread necessary for the cammier engines such as the 3.4 twin cam V6, the Quad Four and some V8s tuned for top end power. If you have one this is the transmission to use for any swap.

Now you may ask what is the point of this little discussion. Simple, many of you may be contemplating a V8 swap but are concerned about the added cost and complexity of finding and installing a Getrag. If you have a V6 with 4 speed, or an 84 with the economy ratios, you don’t need the Getrag. Also decent 4 speeds are available for much less than the typical Getrag ( All Citations with manual transmissions used this 4 speed, but with different combinations of ratios, such as the 2.5 with 3.32 final drive but 0.81 4th gear). In an extreme case, the 6 speeds Chevy sells in the Camaro and Corvette are mainly meant to allow tall gearing for good fuel economy and as a marketing gimick (no flame please, I would love to own one I just want to point out that a 9000rpm Honda VTEC engine would need that transmission, a 6000rpm 5.7 litre V8 does not). With big torquey engines 4 speeds are fine. Now the Iron duke 2.5 like mine, it could use all the help it can get, but since I drive an 84 I have the four speed.

The moral of the story is, if your perfect Fiero must have a V8 than a 4 speed is fine, but if you long for the high pitched scream of an engine on the far side of 6000rpm the 5 speed is the logical choice. The wide ratios of the economy box in my 1984 suits my slow revving iron duke just fine.

Note: All indications are that NO V6 ever left the factory with the 4.10 ratio 4 speed, it was a 1984 only option.

Automatic Transmission Final Drive Ratios:

84-86 L4 had 3.18 final drive.
85-86 V6 had 3.06 (86, at least the GT haven’t seen any in SE had 3.33 optional)
87-88 L4 had 2.84
87-88 V6 had 3.33 (2.84 optional)

All will interchange

Catalytic Converter

The catalyst is used to burn off excess fuel and oil that escapes normal combustion. The catalyst usually fails in one of 2 ways. It either disintegrates or gets plugged up with soot. In extreme cases the guts can melt. (Usually if it disintegrates it blocks up the exit port.) The catalyst needs to be replaced when it fails. You can’t fix it.
You want to know which way it failed. If it fell apart then you can likely just replace it but if it’s blocked up with carbon or melted then try to find out why before you install a new one. If the motor is running rich, burning oil, or leaking coolant then these problems must be fixed before the new catalyst is installed otherwise you’ll wreck the new one in short order.
A quick way to test the catalyst is to measure backpressure at the O2 sensor port. According the June 2001 issue of Motor…
With the engine idling, the pressure will usually be below 1 psi on a good system.
Backpressure reading over 1.5 psi is cause for concern. Next, bring the rpm to 2000 and check the pressure again. A good system will usually show less than 2 psi. If the pressure is over 3 psi, the catalyst is most likely going south.
Of course most people don’t have the fancy commercial one of these lying around, but they can be made. You’ll want to use some metal or high temperature flexible tubing to keep the gauge away from the worst heat. You also want a gauge made for low pressure, something with a 5-10psi top end.
You can use an old O2 sensor or spark plug to fabricate the exhaust fitting.
If the catalyst croaks… Once the catalyst is off make sure it hasn’t blown its cookies down the exhaust pipe. With Fiero’s exhaust setup, you can probably suck the stuff back out of the muffler with a shop vac. (Empty the vacuum before starting so you can tell what came out of the exhaust.) If you don’t check for this you could fry the new catalyst. At the very least the exhaust will still be restricted and likely hurt performance.
Many people think the catalyst does nothing but rob performance. Once upon a time this may have been true but today’s high flow catalyst units present very little restriction of exhaust flow. In the vast majority of cases you gain nearly the same performance increase with a new catalyst as having a straight pipe.
·     A straight pipe may give a HP increase but can reduce low-end torque in many engines.
· A straight pipe on an engine with backpressure EGR may also cause odd problems. These engines must have some backpressure to operate properly.
It is illegal in some places to put used catalysts in the trash. Even when it isn’t illegal try to dispose of it at a muffler repair shop or some other place that will send them to be recycled. (They recycle both the metal and the catalyst material.)

EGR

Note! An altered or defective exhaust system can screw up operation of the EGR valve on the L4. How much depends on the specific alteration or defect.
The EGR, Exhaust Gas Recirculation, valve is used to limit emissions and to prevent engine knock. On V6 the valve is ECM controlled but on the L4 it is operated by a combination of engine vacuum and exhaust back pressure.
There’s not much to go wrong with the valve. It can jam or leak which is usually caused by carbon and rust in the valve base. The diaphragm that moves the valve can deteriorate and leak. That’s about it. (In one odd case, I had the return spring or something in the vacuum chamber broke.)
You have to watch that the valve is connected to the right vacuum source. That information is on the VECI, Vehicle Emission Control Information, label on the deck lid. Hooking it up wrong can make it open at the wrong time or not at all.
The main problems with this valve on the V6 are that the valve plumbing likes to crack and the ECM control solenoid likes to get trash in it. The cracks of course hurt engine performance, if the car even runs with these vacuum leaks.
The control solenoid can sometimes be cleaned but you have to watch what you clean it with. You want a plastic friendly solvent that leaves no residue or lubricant behind to collect more dirt.
If you suspect EGR valve problems, take it off and inspect it. The gasket for the L4 valve is only about $1.00. I imagine the V6 one is about the same. (FelPro gaskets…) Always install a new gasket if you remove the EGR. A small exhaust or vacuum leak can cause major hair pulling…
Carbon or corrosion on the valve can hang the valve open or shut. You may be able to clean carbon off with EFI system or Carburetor cleaner. Corrosion will usually mean valve replacement.
Shake the valve. Noise is bad… Nothing in it should rattle.
Push the diaphragm up. You may have to carefully use a tool of some type. (A stick of Plastic or Wood is probably safer than metal.) Does it move smoothly and return to the closed position by itself? If not the valve probably needs replacement.

When does EGR open?

That depends on the EGR in question. I can tell you when it should definitely NOT open. It should not be open at idle or at WOT. Otherwise… On the ECM controlled ones it will open whenever the ECM is programmed to open it.
On backpressure ones, like the Fiero stock 4 cyl, it will open at certain combinations of vacuum and exhaust pressure. Exactly when those conditions will be met is hard to say. It will vary based on the condition and configuration of your car and you driving habits.

Service Warning!

THIS APPLIES TO ALL VEHICLES FITTED WITH THE UNIVERSAL EGR VALVES.
Many replacement EGR valves are of the universal type and come with metering washers that are affixed to the valve prior to installation on the car.
These washers MUST be staked in place. Do not depend on the gasket to hold them. If the washer comes loose it will screw up the metering allowing more exhaust gas flow than it’s supposed to. The washer could even fall into the motor and cause major damage.
To stake them down place a punch or the corner of a chisel in the base of the EGR valve next to the washer seat. Hit the punch to dent the valve base and force metal toward the washer. Do this in at least 3 locations around the washer.
Record the number of the original valve to both the sticker included with the valve and a permanent location on the vehicle or in some other place you can find it again. The label often fades. You’ll need the number if you ever have to replace it again.
To select the correct washer you need the code stamped into the OE EGR shell…

Fuel Vapor Canister

The Fuel Vapor can is a little confusing for many people. It is simply a can of charcoal with a vacuum controlled air vent stuck on it. The emission control purpose of the canister is of course to prevent fuel vapor from leaving the gas tank but it also saves you money if it works right. Fuel that evaporates from your tank costs money and gives nothing in return. The canister catches this fuel and lets the car use it. It’s a small amount at any one time but over the life of a car it can really add up especially in hot climates. A canister that is working right will not hurt performance and will add ever so slightly to your MPG.
The Canister Purge uses two vacuum lines. The large one goes to manifold vacuum and carries the fuel vapor into the engine to be burned. The small one is the control line and goes to a port on the throttle body that opens upstream of the throttle butterfly. When the throttle opens beyond a certain range the purge control valve opens and allows manifold vacuum to draw the vapor from the can.
The only maintenance the canister needs is periodic checking of the vacuum lines and filter. There is a floss filter on the bottom to trap large dirt from entering the can and plugging it up. That filter needs to be kept clear of major trash and should be replaced once in awhile or when damaged. (The filter costs
about a dollar at Wal-Mart.)
There are only a couple things that can go wrong with the canister. It can be damaged by cracking the thing or by over filling the gas tank. “Topping off” the gas tank can force fuel up the vent line into the can and ruin it. While the fuel pump nozzle is supposed to shut off when the tank is full, they are often bad and can pressurize the fuel tank enough to force fuel up the vent. Certain types of “Vapor Recovery” nozzles are great for this.
The purge control valve can fail or its line can be connected to the engine wrong. Either can cause problems. The routing of these lines is also on the VECI label.
The fastest way to test for drivability problems caused by the vapor can is to disconnect and block both vacuum lines. If the problem stops, the vapor can is bad.

How does the canister work?

This explanation is based on an article from Motor Magazine or Motor Age that I can’t find anymore…
The canister is filled with high-grade charcoal similar to a gas mask. When fuel vapors expand out of the fuel tank, they cling to the surface of the charcoal.
The important thing here is that fumes don’t soak into the charcoal grains like most people think. This “small” fact is what makes the whole canister possible.
When the canister is purged fresh air is sucked thru the canister, which knocks the fuel molecules off the charcoal and caries them into the engine. Canister purge in older cars, including Fiero, is usually controlled by a ported vacuum signal from the carburetor or throttle body. In many newer vehicles the canister purge is controlled by the ECM/PCM.
If liquid fuel gets into the canister it will soak into the charcoal just like lighter fluid does in your grill. Once that happens the charcoal is ruined. Even if you could dry out the liquid fuel, the carbon won’t recover.

PCV system

The Positive Crankcase Ventilation system is both an emission control and a significant improvement to engine longevity. The job of the PCV system is to remove fumes from the crankcase and burn them. These fumes pollute the air and if not extracted from the engine they promote contamination of the oil and varnish on internal parts.
There are 2 major parts in the system, an air filter, and the PCV valve. Make sure both are clean and that the vacuum line(s) and vent hose are sealed.
The PCV valve should be replaced every couple years at most. There is a spring in the valve that is critical to proper operation. The spring will weaken over time. A bad PCV valve is hard to detect. The obvious test of shaking it only tells you it’s not stuck closed. It won’t tell you the spring is weak.
Make sure you clamp all the joints in the PCV line. The rubber parts can’t be trusted to seal themselves. Don’t over tighten the clamps or you will damage the soft parts.

Emissions Service Parts

Note: Be careful buying PCV parts for the 87-88 4 cylinder motors! Many parts books incorrectly list them as using the same parts as the older 4 cylinder engines. Double-check them against Grand Am or Olds Cutlass Calais of the same years.
I had a heck of a time finding the correct PCV filter for my DIS motor until I looked it up under the Olds line. I’ve noticed some parts catalogs also list ignition parts wrong as well.
This is a quick list of stuff I’ve seen listed and where. I’ve seen AC Delco emissions parts for DIS 4 at Parts America. I imagine they cover other years but I didn’t feel like checking them all. (I think the same vapor can is used in all Fiero.)
The part numbers for the DIS motor parts…

As far as I can tell, the AC EGR is an OE matched unit. (At least that’s the picture they have on their web site.)
GM Parts Direct lists the Vapor Canister for about $25. (Use GM # 17075840)
They don’t have the EGR valve.
No AC Delco part was listed for the one V6 I looked up. (86 GT) Because the V6 valve is ECM controlled it’s not as critical who made it as long as the new part is high quality and provides the correct gas volume.
If you can’t find a stamping number to use for universal EGR’s, try using the information listed with Niehoff Ignition’s parts. Here’s the info they list on Parts America for an 86 GT with their part # FE134A valve. (I’ve never use Niehoff stuff but there catalog info is handy. They are the only one I’ve seen so far that lists data like this.)
[E. G. R. Valve] OE Number 17085897; Orifice Number 11; Use EGR Valve Gasket {FE302}; Use EGR Tube Gasket {FE354}
Notice the OE stamping number above. You could use that bit of info for any universal EGR. (The one you have may use the same metering washer or a different one. Get that info from the chart that comes with the new EGR.)
The V6 EGR solenoid I found listed under “Vacuum Regulator Valve” in the Fuel Injection parts. Parts America says it usually ships in 5 business days.
AC DELCO 214-361 $102.99 [EGR Vacuum Regulator Solenoid Valve] GT, SE Listing
Everyone who’s got them likes Rodney Dickman’s catalyst kit. It has the needed stainless steel adaptors needed for installation.