Posted by ChuckRock on May 26, 2009

4 cylinder motor mount

There are 2 kinds of motor mount available for Fiero 4 cylinder. (I think this applies to all of them…) You can get them solid or liquid filled. The solid is a little less expensive but the liquid filled is better at isolating vibration. Of the two, I prefer the liquid filled even if it’s a bit less durable than solid. Anything that reduces engine vibration traveling to the car body is a good thing. (The liquid mount is usually the easier one to find in stock.)

How do you detect a bad liquid filled mount?

In the drawing above I’ve colored the steel body of the mount green. Notice how the rubber passes over the safety pin. The motor bracket can touch the rubber over the pin but mustn’t compress it any significant amount. If the motor bracket is resting against the metal body or the safety pin then the mount is bad and must be replaced.
Note! It is entirely possible to get a new mount that is bad! When you buy a liquid filled mount, you should not hear allot of sloshing when you shake it. If it sloshes, it’s bad. Don’t accept it! (The mount will usually have a tiny air bubble in it but it shouldn’t slosh like a half empty soda bottle.)
A sloshing mount has air in it and won’t be able to support the motor. Once installed it should pass the above inspection, if not then take is back and get another.

Changing the Mount

You need a 15mm socket and a 15mm box end or flair fitting wrench. (I prefer the flair wrench. It seems to grip better.)
Disconnect the battery.
Disconnect one end of the torque strut. (Dog Bone)
Jack the car, install a jack stand, and remove the right rear wheel. The top nuts are easier to get if the wheel is off. (Yes, I’ve tried both ways… take the wheel off.)
Remove all four nuts from the mount. These are lock nuts and will need to be turned with a wrench all the way off.
Jack the motor up. Use a block of wood between the jack and oil pan. (If you don’t use the block the oil pan could collapse.) Keep the jack over toward the transmission to it will lift straight.
Pull out the old mount and clean the motor bracket. Don’t loose the top washers that are likely buried in crud.
The new mount only fits one way.
Put the heat shield, the nuts and washers back on.

Mount care

If you have a 4 cylinder using traditional spin on oil filters… (This isn’t an issue for filter in pan motors.)
When changing the oil, stuff a rag into the engine bracket to catch oil that runs down while you change the filter. If you can keep oil off the mount then it will last longer.
Consider making a shield for the mount out of some aluminum sheet and sandwich it between the top of the mount and bracket. This will help keep oil that runs down the bracket from pooling on top of the mount. Constant soaking in oil will shorten the life of the mount. It doesn’t matter much how you make it as long as it deflects the oil that invariably spills from the filters during changing.

Transmission and V6 Motor Mounts

These are solid rubber mounts and there’s not much to them. Most of the time you can easily see damage to a bad one. Sometimes the mounts tear away from the metal parts too cleanly to be obvious. If you think a mount may be bad and you can’t see damage, try gently jacking up whatever the mount supports.
Jacking will spread open any tears in the rubber. Don’t get rough with the jack or you could tear a good mount.
When ever you have to replace a mount make sure you loosen all the others.
That way the mounts can all settle into position without loading.
Except for 86.5 and later 4 cylinders with automatic transmission, you’ll almost never see just one mount that is bad. The front mounts and the dog bone are the most likely to fail but it’s entirely possible for all of them to be bad. (The 86.5 and later 4 cylinder/AT setup only has one engine mount and one transmission mount. Read the torque strut article for more info…)
Oil soaked mounts may not be torn but are probably considerably softer than they should be. Oil and other chemicals break down the rubber over time.
Always clean off any oil that spills on them.

Polyurethane mounts

Polly mounts are generally perceived as better than OE style vulcanized rubber mounts. In some applications they probably are but for general use they simply aren’t needed and are unlikely to do anything performance wise for the car.
Depending on just what ones you buy, many OE style mounts are stronger than the ones that came with the car.
Polly can also pass more vibration to the car, especially at idle in automatic transmission cars. (This has been proven with polly dog bones. The 4 cylinder motors are the worst for this.)
Polly mounts can add some color to the engine bay. They may tolerate the heat better.
They are more resistant to oil grease and other chemicals, which shouldn’t be much of an issue. The mounts shouldn’t be getting allot of stuff on them in normal use. The main source of oil on mounts is usually a sloppy oil change or a leaking gasket. Rubber mounts usually last years in even the worst environments.

Posted under Engines

Posted by ChuckRock on April 27, 2009

HOW-TO bypass the auto transmission controls in the 3800 PCM

I have gotten a couple of questions on how I was able to bypass the auto trans controls on a stock 3800 PCM in order to prevent early rev limiters and other drivability issues it had when I was not using an electronic automatic transmission. I originally tried this with a 92 PCM controlling the 3800 Series I SC engine I installed into a Fiero with a 125-C trans. While this mod worked for the non-electronic auto trans, it should work with manual transmission equipped vehicles as well. First, let me explain why you will have a problem with a stock PCM when there is no electronic automatic transmission hooked to it. The GM PCM looks at a couple of sensor feeds as well as looks to see if there are shift solenoids hooked up to it. If it finds a fault, the PCM will most likely take action to prevent what it thinks is a failing transmission and reduce power output or cause other drivability issues. While this thread is general in nature, most GM PCMs work on the same principles but all may not be compatible with this mod. Be that the case, this mod is a cheap attempt to working around an expensive OBDII reprogram if that is what you are working with.

The Shift and TCC Solenoids

While the PCM grounds the shift and TCC solenoids in order to control their operation, it also looks to these same circuits while they are not activated to see if there is a return signal (ie: B+ 12v feedback from the ignition circuit). If it does not see a return signal, a fault code will set and the PCM may take actions to prevent “damage” to the transmission it thinks is there.

To bypass the shift and TCC solenoids, you simply need to connect standard 194 light bulbs to these individual circuits coming from the PCM and then connect the other side of the bulbs to ignition B+. The light bulbs will then serve as a “load” which will simulate the solenoids. Be sure you keep these bulbs away from any low temperature plastics as they will turn on and off at various times as the PCM “thinks” it is shifting the trans.

The Pressure Control Solenoid (4T65-E/4T80-E only)

The PCS is a solenoid that the PCM uses to regulate line pressure in the 65-E and 80-E transaxles. The same rules apply here as they did with the other solenoid circuits with the only difference being that this circuit needs to be loaded differently. In a TRANS-GO vacuum modulator conversion kit for the 4L60-E they supply you with a 6 ohm, wire wound resistor to take the place of the PCS and fool the PCM into thinking there is a solenoid there. While a resistor would work I suggest finding a 12v light bulb of a similar resistance as the resister would get very hot after a while as it is intended to remain immersed in trans fluid. The only purpose of this mod is to prevent PCS related trouble codes.

The Transmission Range Position Switch

He is a typical diagram of the PRNDL position (gear selector range) switch used on the FWD type electronic transmissions.

As you can see, there are 4 main switches besides the standard park/neutral switch that the PCM uses to determine transmission range selection. When I bypassed the 3800ISC 92 PCM for use with the 125-C, I simply grounded the yellow and white wires going to the PCM and then hooked the blk/wht and grey wires to the NC (normally closed) side of a relay that would ground them anytime I wanted the PCM to think the car was in gear and would cut ground from them any time I wanted the PCM to think the car was in neutral or park. This gave the illusion to the PCM that it was either in Neutral or Drive3.

Using a non-electronic automatic trans with a P/N grounding position switch (like what the Fiero’s 125-C has stock) I would hook a standard relay up in this fashion:
Relay term — connect to
85 — IGN B+
86 — P/N wire from trans switch (ORG/BLK)
30 — Ground
87 — not used
87A - BLK/WHT & GRY wires going to PCM

If you don’t have an automatic, you can wire this relay to the brake or clutch switch in one of the following ways:

For a switch that supplys B+ when pedal is depressed:

85 — Switched B+ from pedal
86 — Ground
30 — Ground
87 — not used
87A - BLK/WHT & GRY wires going to PCM

For a switch that supplies B+ when the pedal is NOT depressed, simply wire the relay as follows:

85 — Switched B+ from pedal
86 — Ground
30 — Ground
87 — BLK/WHT & GRY wires going to PCM
87A - not used

The VSS or speed sensor

Here is where it gets tricky. Most 3800 pcm’s like to see a 29-31 pulses per tire revolution signal from the VSS (depending on reluctor count). Using the standard tire size from a 3800 SC equipped vehicle, this works out to about 24,000 pulses per mile; which is about 6 times the amount that the stock reluctor from a getrag gives out. Another problem is the 3800 PCM is looking for an analog VSS signal whereas the stock getrag is a digital signal which most PCM’s are not compatible with on that particular input. I have not ever attempted to make the stock PCM programming compatible with the getrag signal but it may work. It also may need an adapter to work, one similar to the diagram I have on my website at http://dtcc.cz28.com/fiero/fmods.htm . While you don’t really need an accurate signal if you have a manual trans, the PCM would like to see that the car is moving or it is stopped for drivability and idle issues. If you are using a non-electronic auto and still want the PCM to control the TCC normally, you will need to get this signal pretty close otherwise the PCM will assume you have a slipping TCC issue or incorrect vehicle speed and will disable TCC operation.

The Trans Gear Pressure Switch (4T65-E & 4T80-E only)

I have not attempted to bypass these switches so I don’t know how the PCM would react if it didn’t see them operating. Honesly, I think they are meant for the transmission controlling part of the PCM and probably don’t play a role when it comes to the REV limiter and idle characteristics of the engine control side. Of course not hooking these up will cause a few trouble codes.

Hope this information is helpful to a few. While it is meant to bypass the trans control part of the PCM I cannot guarantee that it is compatible will all PCM’s and engine/transmission platforms. What it does do is gives you a cheap workaround to try and even if it doesn’t work, you are not out that much money.

Posted under Conversions

Posted by ChuckRock on January 8, 2009

Northern California Fiero Club

Welcome to the club! This is the Northern California chapter of the Fiero Owner’s Club of America. In 1988 this social club was established with the intention to:

• Help each other out with our Fieros
• Plan outings
• Encourage the preservation of Fieros

Our members range in age, and have a variety of interests in Fieros. Some owners prefer pure stock, others modify, while others turn their Fieros into specialty kit cars.

We plan several group events each year. Join us! Get involved!

Posted under California

Posted by ChuckRock on October 14, 2008

Chevy 4.3L 262ci V-6 - The 3/4 350

writer: David Freiburger

photographer: David Freiburger

We were more excited to buzz this turkey on the dyno than we usually are with some whumpin’ big-block. Why? It’s different. Not too many people build V-6s any more. Perhaps we found out why, but we still think it’s neat-or at least cute. See, the ‘85-up Chevy 4.3L, 262ci V-6 is very much like a small-block Chevy minus the number 3 and 6 cylinders (check the valve layout and you’ll see how we came up with that conclusion). They’re common in ‘88-up trucks, and we still get so many letters asking how to feed a V-8 to an S-10 truck that this time we elected to answer the question no one asked: How do you get more wheeze out of the stock 4.3?

But first, a little V-6 lore. The units we’re concerned with are the Chevy 90-degree variety, meaning that the cylinder banks are set at a 90-degree angleto each other, just like a small-block V-8. The bore centers (4.400) and deck height (9.025) are also identical to a Mouse motor. The ‘85-up 4.3L V-6 has the same bore and stroke as a 350 V-8 (4.000×3.480), and takes the same pistons, cam bearings, main bearings, valvetrain parts, timing cover, oil pump, and front dress. Any V-8 trans will bolt right up to the 90-degree sixer. The 4.3L has much more performance potential than the ‘78-’79 200ci V-6 or the ‘80-’84 229ci version due to those engines’ small 3.500- and 3.736-inch bores (they’re like mini 262ci and 305ci V-8s). Also, the 200 and 229 have semi-odd-fire cranks (132/108-degree firing), while the 4.3Ls are true even-fire engines. Not that 4.3s aren’t still quivering little suckers, hence the introduction of a balance shaft in the lifter valley of 4.3s beginning in late ‘92 or early ‘93. The even-fire 4.3 cranks can be identified by their split-pin cranks-each rod pin is offset in the middle by 30 degrees. There are also common-pin V-6 cranks (they look just like conventional V-8 cranks) developed for the Chevy V-6’s Busch Grand National racing days, but those are odd-fire units.

Like the Chevy V-8, the 90-degree V-6 saw some transition during production: factory hydraulic roller lifters, one-piece rear-main seals, and center-bolt valve covers all appeared in ‘86-’87. Just like a V-8, one-piece-seal cranks can be swapped into two-piece-seal blocks with commonly available adapters. The 4.3L has been offered with carburetors, throttle-body injection, and the current central-port Vortech injection that was introduced in ‘95 (we think) along with an intake-manifold flange that requires vertical bolts; as far as we know, a carbureted intake is not available for V-6 Vortech heads.

So our pick for a simple, budget, performance V-6 would be an ‘85-’92 unit without a balance shaft, and we have a slight preference for the earlier units with perimeter-bolt valve covers. They just look better, and based on our inspection of junkyard heads, we suspect that the early ones flow better. But avoid the 200 and 229 heads, which have 1.84-inch intake valves. Speaking of heads, you’re sorta stuck with stockers. There was a time when GM Performance Parts had 23-degree, direct bolt-on performance heads and manifolds, but now only the hardcore 18-degree race heads and intakes are available; you can still get all kinds of iron and aluminum race blocks, too, including big-bore capability and priority-main oiling. We learned that Scat Crankshafts still has the very last few sets of Brodix 23-degree V-6 heads, but we were unable to find any others that are affordable. Similarly, intake manifold selection is pretty slim, and while most cam manufacturers can grind anything you want, the only off-the-shelf sticks are pretty mild. We decided to see what we could squeeze out of this thing with readily available parts and the production heads and block, skipping any rocket science. To duplicate every little nut and bolt we used would run about $3,000, including machine work.

The result was 301 hp at 5,500 rpm and 312 lb-ft at 4,700. Puny, but let us remind you that it’s still 50 hp per cylinder (a similar 350 V-8 would make 400 hp), which is pretty good for the very mild parts we used. Besides, at 0.060-over, it’s just 270ci. Naturally aspirated, our V-6 should put an S-10 into the 14s, and with forged pistons and studded mains, we’re ready to nitrous this thing to at least 400 hp or add a Vortech blower for an easy 450 to run in the 12s or better. Even more interesting, Allstar Performance sells brackets to swap a 90-degree V-6 where a V-8 used to be, and the resulting engine setback could make this thing killer for handling applications in, say, a third-gen F-body.

Enough justification. We kind of like our little motor. Have a look at how we conspired with Dougan’s Engine to make it run twice as hard as it did stock.

1. We began the 4.3L V-6 buildup with the knowledge that the pistons are the same as a 350 V-8’s. Our pick was the Speed Pro LW2256-F-060, a lightweight forging (686 grams) with four valve reliefs with 6.1 cc of dish. The rings are Sealed Power R9902-060 file-fits set at 0.024 and 0.020, a bit wide so we can hammer this thing with nitrous and not worry about butting the end gaps. The V-6 is known as a shaker, so we had Dougan’s Engine do a precision balance job.

1. The 4.3L conrods are 5.700 inches like a 350, but the journal size is 2.250 rather than the V-8’s 2.100; we presume that the reason for the bigger journal is to add strength to the offset-style rod pins on the crank. Dougan’s was able to modify Milodon 190,000-psi rod bolts for a 350 application just by clearancing the heads a bit, as shown on the right.

1. If our descriptions of a split-pin crank seemed a bit muddy, this photo should light a bulb for you. See how two rods (arrows) on the same journal are offset a bit? They’re also separated by a cast-in thrust surface, and hence, the rods are narrower than a V-8’s. Still, Sealed Power makes tri-metal bearings for the application (PN 6-1020CP). The Milodon main studs and oil-pump stud were sourced from a V-8 application. The oil-filter pad is much tinier than a V-8’s; it takes an AC PF52 filter.

1. The Speed Pro pistons come stock with 6.1cc of valve relief. Combined with stock heads that Dougan’s checked at 68cc chambers, pistons that we set at an average of 0.010 below deck, and Fel-Pro head gaskets with 0.041 compressed thickness, the V-6 would have 9.63:1 compression. Stock was 8.6:1. Because we changed plans midstream and decided to someday try the Vortech blower for carbs on this engine (see the story in this issue), we asked Dougan’s to mill a 3.475×0.060 dish in the pistons for a total volume of 12 cc, lowering the compression to 9.08:1. For now, it runs fine on cheap gas.

1. To wrap up the bottom end, we twisted Dougan’s builder Jeff Jacobs’ arm until he agreed to modify our Milodon 350 windage tray to fit the V-6. He cut a few inches off the front, enlarged one bolt hole (arrow) to clear the dipstick tube, and tweaked a few louvers to fit the stock oil pan. Also check out the oil pump and pickup-they are Sealed Power part numbers 224-43469V (pump) and 224-14263 (pickup), an upgrade over the stock V-6 parts because they employ a 3/4-inch pickup tube. The steel oil-pump driveshaft is Sealed Power PN 224-6146E.

1. Dougan’s Ray Field spotted the funky V-6 balancer (left) with a lip around the edge that might prevent the use of aftermarket pulleys even though the bolt pattern is the same as a V-8. You can use conventional short- or long-water-pump accessories on the 4.3. We also wanted a steel balancer in case we ever add the blower, and we needed an SFI-approved balancer for the track. Dougan’s found that the Pioneer balancer (PN 872021) on the right is a 6.125-inch, lightweight V-8 unit that would fit perfectly. Neat! The 4.3L is an internally balanced engine like a 350.

1. A 4.3L can be cammed just like it was a 350 because each cylinder has the same displacement as its V-8 bro, though cams will seem bigger in the V-6 because there’s less power overlap. Off-the-shelf cam grinds are pretty tiny for use with the OE computer-controlled applications that house most of these engines. We nabbed Comp Cams biggest hydraulic roller for our factory roller block, a 280HR with 224/224 duration at 0.050, 0.525 lift, and a 110-degree lobe-separation angle. The cam kit (PN K09-430-8) comes with cam, lifters, retainers, locks, seals, timing set, valve springs, pushrods, guide plates, and rocker studs. At $638.69 (Summit), it’s the biggest expense of the buildup, but also the key to making this thing run.

1. During assembly, Dougan’s pointed out that the 0.350-inch lobe lift was all the block could take-any more and the hydraulic lifter would hit the stock-style link bars.

1. The valve springs supplied by Comp were PN 986, though Dougan’s stepped it up to a slightly stiffer 987 because we so often see valve float at 6,000 rpm with hydraulic rollers; as it turned out the power peak was at 5,500 anyway. However, either spring has a 1.430-inch diameter and the V-6 heads need to be machined to accept them, then the springs need stiff shims because there’s not much meat in a few of the seats. Dougan’s also modified the heads for 3/8-inch screw-in studs since we didn’t trust the press-in style above 0.500-inch valve lift.

1. Speaking of lift, we amped the cam’s 0.525 lift with 1.5:1 rockers up to 0.560 inch by substituting Comp Cams 1.6: Pro Magnum rockers (PN 1301-12). Next time we’d use the new self-guided rockers (PN 1318-12) and omit the guide plates, as the V-6 heads had some pushrod-angle problems with the V-8-type guide plates. We were surprised that the stock center-bolt valve covers cleared the rockers with no modifications.

1. Because we found no practical aftermarket heads, and because simply cutting one cylinder off a V-8 head won’t work, we had our pal Brulio at Westech Performance hog the stock heads for increased flow. These heads are terrible, and even after porting, they only flow about as well as stock 305 Chevy heads. Peak numbers were 208 cfm on the intake and 190 on the exhaust, which was a giant improvement over the pathetic 138/116-cfm baseline. Helping the cause were Milodon Megaflow swirl-polished, tulipped valves in 2.02/1.60 sizes (PNs 45015 and 45045), an upgrade over the stock 1.94/1.50s. Consider these steps mandatory to making any kind of decent power with your V-6.

1. Fel-Pro gaskets were used throughout our little engine, and even though the intake set was clearly marked, we screwed up the first time and put them on backwards. Do so and you block the water passages to the head at the front of the block; they are shown here properly installed. Also note that we blocked off the heat crossover.

1. Header selection is very limited, and while Edelbrock makes tubular manifolds and systems for truck applications, they wouldn’t fit the dyno. Instead we used a set of long-tube, coated S-10 headers from Hooker (PN 2842-1) They have tiny 15/8-inch primaries. 26-inch tubes, and small 21/2-inch collectors. We ran all our tests with collector extensions but no mufflers.

1. Ignitionwise, MSD still makes even-fire (PN 8597) and odd-fire (PN 8596) Pro Billet distributors for the 90-degree V-6. We used an even-fire unit with MSD 8.5mm Heli-Core wires and a Digital-7 ignition box. Note that the Demon or Holley-type carburetors will not fit this engine unless a 2-inch carb-spacer is used-otherwise the float bowls hit the distributor and water neck. If you don’t want a cowl hood, stick with the Edelbrock carb.

1. Intake-manifold selection is very limited, and we chose an Edelbrock Performer (PN 2111). This is a very low-rise intake, and we made best power with a 2-inch spacer from Wilson Manifolds. The initial carb we used was an Edelbrock 500, which seemed to be jetted perfectly right out of the box. It turned in 288 hp at 5,400 and 303 lb-ft at 4,400. But strangely, the V-6 saw about 1.5 inches of manifold vacuum at WOT, indicating that the carb was a tad too small.

1. We didn’t have a 600-cfm Edelbrock to try, so we added a 650-cfm Mighty Demon. It’s nearly 300 bucks more than the Edelbrock 500, but kicked the power up to what we were looking for: 300 hp and 316 lb-ft.

The Buzz of Power
RPM	HP	TORQUE
3,500	194.8	292.3
3,600	200.5	292.4
3,700	209.5	297.3
3,800	216.4	299.1
3,900	224.9	302.9
4,000	232.4	305.1
4,100	241.5	309.4
4,200	250.3	313
4,300	258.1	315.2
4,400	265.3	316.6
4,500	269.6	314.7
4,600	274.9	313.9
4,700	279	311.8
4,800	285	311.8
4,900	289.6	310.4
5,000	291.9	306.7
5,100	293.3	302.1
5,200	296.4	299.4
5,300	297.1	294.4
5,400	297.3	289.1
5,500	301.2	287.7
5,600	301.1	282.4
5,700	300.8	277.2
5,800	299.1	270.8
5,900	296.6	264
6,000	293.1	256.6

Posted under 4.3L, Engines