ECM upgrade (1227730) for stock 2.8

Recently a friend of mine brought me his Fiero to have a swap done. He had a very high mileage stock 2.8 and 125-C and wanted me to swap in a lower mileage 2.8 and 440-T4 OD transmission. Not content with sticking with . . . → Read More: ECM upgrade (1227730) for stock 2.8]]>

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 . . . → Read More: Chevy 4.3L 262ci V-6 – The 3/4 350]]>

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.

A 3800 Series II L67 Supercharged engine in a 1998 Buick Regal GS.

The L67 is the supercharged version of the Series II L36 and appeared in 1996, one year after the normally-aspirated version. . . . → Read More: 3800 V6 Series II]]>

3800 V6 Series II

overall weight (to 392 lb).

[edit] L67 Supercharged

A 3800 Series II L67 Supercharged engine in a 1998 Buick Regal GS.

The L67 is the supercharged version of the Series II L36 and appeared in 1996, one year after the normally-aspirated version. It uses the Eaton Generation 3 M90 supercharger with a 3.8″ pulley, a different throttle body, fuel injectors, cylinder heads, and lower intake manifold than the L36 uses. Both engines share the same engine blocks, but compression is reduced from 9.4:1 in the L36 to 8.5:1 for the L67. Power is up to 240 hp (180 kW) and 280  lb·ft (380 N·m) of torque. Final drive ratios are reduced in most applications, for better fuel economy and more use of the engine’s torque in the low range. The engine is built in Flint, Michigan. The engine was certified LEV in 2001.

This engine is or was used in the following cars:

• 1996-2005 Buick Park Avenue Ultra
• 1997.5-2004 Buick Regal GS
• 1996-1999 Buick Riviera (optional 1996-97, std. 1998-99)
• 2004-2005 Chevrolet Impala SS
• 2004-2005 Chevrolet Monte Carlo SS
• 1995-2004 Holden Commodore (VS, VT, VX, VY)
• 1995-2004 Holden Statesman (VS, WH, WK)
• Holden Ute (VU, VY)
• 2001-2004 Holden Monaro
• 1996-1999 Oldsmobile Eighty-Eight LSS (limited)
• 1996-2003 Pontiac Bonneville SSEi
• 1997-2003 Pontiac Grand Prix GTP

4.3L TBI Injector Flow and Factory Cam Specs

Here’s a reference chart of TBI injectors.

Flow is lb/hr @ 13psi

4.3L S10 to Fiero Engine Swap

Old Engine Removal

Sorry, I didn’t have my digital camera when I started actually tearing into the car. But never fear, I still have some pics to share of the end result.

4.3L GM 90 Degree V6 Info

Rebuilding the New Chevy 262, Doug Anderson, Automotive Rebuilder, April 2000

Thanks to all of those who have contributed information for this article, including the people at GM Powertrain – Lansing Engine.

. . . → Read More: 4.3L GM 90 Degree V6 Info]]>

4.3L GM 90 Degree V6 Info

Rebuilding the New Chevy 262, Doug Anderson, Automotive Rebuilder, April 2000

Thanks to all of those who have contributed information for this article, including the people at GM Powertrain – Lansing Engine.

Back in the late 1970s when everyone was worried about the “gas crunch,” Chevy needed some smaller engines in a hurry, so it created a new family of junior-sized V6s by chopping two cylinders off its existing V8s. This enabled GM to shorten the development process dramatically because it was able to adapt a proven design. But it also allowed it to share a lot of the existing tooling from the V8 production lines so the engines could be on the road sooner.

The original 200 V6 that came out in 1978 was based on the 262 V8, and the 229 V6 that came out in ’80 that was based on the 305. By 1985, both were replaced by the 262 V6 that was based on the 350. It was originally installed in both cars and trucks; since ’87 it has been used primarily as a truck engine. It also has been updated several times to make it one of the best in the industry. The engine combines performance and economy in a reliable package for most of GM’s pickups, vans and sport utility vehicles.

Although the basic architecture has remained the same, GM has made a lot of changes to the 262 as it has continually upgraded and improved the original design. In the process, it has changed the block to accommodate a one-piece rear seal, added a roller cam and a balance shaft, modified the crank and rods, upgraded the pistons and revised the heads for better performance and emissions.

There are some subtle differences between the engines built in the two different plants, too. For example, the cranks and rods used in a Tonawanda engine are not the same as the ones used in a Romulus engine. There can be problems if they are intermixed. So, let’s take a look at how it all began in 1985 and see how the 262 has evolved over the past 13 years, remembering that most of these changes were made to improve power; reduce emissions; increase mileage; and reduce noise, vibration and harshness (NVH).

BLOCKS

1985: The original block in ’85 was a 14071177 casting. It had a two-piece rear seal, a flat tappet cam and a fuel pump hole because all of the trucks still had carburetors. Just for the record, there were some ’86 blocks shipped with pans for ’85 service replacements, so it is possible for a customer to have an ’85 car or truck with a one-piece rear seal.

1986: In 1986, the block (c/n 14088553) was modified to accommodate the new one-piece rear main seal. The fuel pump hole was still open, even though it wasn’t always needed, because all of the cars and some of the trucks came with throttle body injection.

1987- ’94 WITHOUT BALANCE SHAFT: In 1987, a roller lifter cam was installed, so the block was changed again. Two bolt bosses were added in the middle of the valley for the lifter retainer that kept the rollers properly located on the cam and perpendicular to it. This same basic block was used through ’91 for everything, and in ’92 through ’94 for all of the engines without balance shafts except for one small difference – some of the blocks came with four bolt holes for the tunnel style retainer beginning in ’92. There were several different castings used, including the 10105867, 10172756, 14099073, 14093683 and 10066011 with the two-bolt retainer, and the 10172756, 14099073 and 10066061 blocks with the four-bolt retainer.

1992 WITH BALANCE SHAFT: The L35 balance shaft engine was introduced in ’92, so the block was modified to make room for it above the camshaft. The lifter retainer was changed to the tunnel design because of the balance shaft; it had two bolts on each side instead of the two in the middle.

There were two versions of the balance shaft blocks in ’92. The “first design” block had a needle bearing on the back of the balance shaft that was lubricated by the oil mist from the valley. The “second design” had a sleeve bearing that was pressure fed through an additional drilled passage in the back of the block.

All of the 1992 “first design” (c/n 10105903) and “second design” (c/n 10224834) blocks were missing the two bolt bosses, one on each side, that were used with the reinforcing struts for the automatic transmission on some of the ’93 and later applications, so they can only be used in ’92. Be sure to double-check the 10224834 “second design” blocks, though, because some of them came with the strut bosses in the later years so they can be used for the ’93s and ’94s.

1993-’94 WITH BALANCE SHAFT: Things got more confusing with the balance shaft blocks in ’93-’94. All of these engines have to have the two extra bolt holes for the strut bosses and 10 bolt holes for the tin front cover. See photo. There are five castings that may or may not be right:

•All of the 10224534 and 10224535 blocks have the two strut bosses and 10 holes for the front cover, so they will fit everything in ’93 and ’94;

•The 10227196 castings have the strut bosses, but they came with either six or 10 holes;

•The 10224834 blocks have 10 bolt holes, but they came with or without the strut bosses;

•The 10235359 blocks were the most confusing because they came with or without the two strut bosses and with either six or 10 holes for the front cover!

Consequently, all of these castings must be checked and sorted by both casting number and features in order to be sure that they will work in everything in ’93 and ’94.

1995 WITH BALANCE SHAFT: 1995 isn’t a whole lot better. All of the ’95 engines had a balance shaft and the strut bosses, but the flange around the timing gear was changed to accommodate the new plastic front cover. The overall shape stayed the same, but the flange was noticeably wider with big bulges around six of the bolt holes. See photo.

There was a mid-year change that can cause problems, too. The early engines used a “first design” tin front cover with 10 bolt holes. The later ones had the “second design” plastic cover that had only six bolts, so the flange can have either six or 10 holes drilled in it. See photo. That means that the tin cover won’t work on a block that was drilled for a plastic cover, so the blocks aren’t always interchangeable.

Things can get confusing in ’95, because the 10227196 and 10235359 castings that were used in ’95 came with the narrow flange in ’94 and were converted to the wide flange in ’95. All of the 10227196 castings had the strut bosses, but some of the earlier 10235359 castings didn’t.

You can use either one of these blocks in ’95 as long as it has the strut bosses and the wide flange with either six or 10 holes drilled for the front cover. But, you must be sure that the corresponding first or second design front cover is installed on the block.

Given the possible confusion over which cover the customer has and which block he really needs, it’s probably better to make sure all the blocks have 10 bolt holes so they will work with either front cover. Do not use an earlier block with the narrow flange with a plastic front cover under any circumstances because it will leak oil.

1996-’98: The block was changed again in 1996. Structural reinforcing ribs were added on both sides of the timing cover and both sides of the block were contoured to follow the shape of the cylinders more closely. See photo. This one is a 14099090 casting. This same block is used up through 1998.

MORE ABOUT BLOCKS

There is one other subtle difference in the blocks. The cam bearing sets are different, depending on whether the block was made in Romulus or Tonawanda. The Tonawanda blocks use two larger diameter cam bearings, one in front and one in back, instead of only one large one in the front. Both bearing sets are available in the aftermarket.

There are three characteristics of each block which will tell you where it was manufactured:

•If it’s a Tonwanda engine, it will have a “T” stamped on the machined surface on the block just in front of the right cylinder head. The engine ID will be number stamped on the pad, and the chamfer on the cylinders will be quite shallow;

•If it’s a Romulus engine, it will have an “R” stamped on the machined surface on the block. The ID number will be made up of a series of dots, and the cylinders will have a deep chamfer on them.

Some of the blocks are drilled for a knock sensor and some aren’t. It’s almost impossible to know which applications came with and without the sensor hole, so most rebuilders drill and tap every block so the hole is there when it’s needed.

LIFTER RETAINERS

The roller cam motors have used three different lifter retainers. All of the ’87 through ’91 non-balancer blocks and some of the ’92s used a flat retainer (p/n 10046165) with two bolt holes in the middle. As of ’92, all of the balancer motors and some of the non-balancer motors came with the tunnel-shaped retainer (p/n 10105916) with four bolt holes, two on the outer edge on each side.

Starting in ’94, Chevy used two plastic retainers (p/n 12551431) that are bolt-in replacements for the tunnel-shaped version. There are some later intakes that will hit on the reinforcing ribs on the tunnel-shaped retainer, so it’s best to use the plastic retainers in all of the blocks that have the four bolt holes.

FRONT COVERS

There have been three front covers used on the 262. The first one came on the ’85 to ’94 non-balancer engines. It’s the same one that was used on the small block Chevy. The second one was a tall, metal cover with 10 bolt holes that was used from ’92 through the ’95 “first design” balancer motors. See photo.

The latest version is a unitized plastic cover that is held on with only six bolts. It came out mid-year in ’95 and was installed on the “second design” engines that had the wide flange with only six bolt holes drilled in it. The plastic cover fits on the earlier balance shaft blocks, but it shouldn’t be used on them because it leaks around the bolt holes. It comes with or without a large hole drilled in the bottom corner for the crank position sensor that was installed on the engines that came with OBD II.

CRANKS

Chevy has used several different cranks in the 262. They came with one- or two-piece rear seals and in both light and heavy versions that were specific to each engine plant. Here’s an overview:

1985: The 1174N casting came with a two-piece rear seal and a flange in the back. See photo.

1986-’87: The 14088640 and 10105865 Tonawanda castings with a one-piece seal were both used only for heavy applications during these years. See photo.

1988-’98: The Tonawanda cranks were all 10105865 castings that came in both light and heavy versions.

1988-’98: The Romulus cranks were all 10055480 castings that came in light or heavy versions.

All of the engines with the one-piece seal were externally balanced with specific flywheels and dampers, but the cranks were also balanced according to the weight of the pistons and rods that were installed in the engine; it’s important to use the right combination of parts. Unfortunately, there’s no sure way to tell a light crank from a heavy one short of knowing where it came from and marking it at teardown or spinning it on a balancer. There are a couple of clues that can help, though:

•All of the 14088640 castings are heavy cranks that can be used in either the ’87 to ’94 non-balancer engines or in the ’93 to ’95 VIN “Z” balance shaft motors with the heavy pistons.

•If a 10105865 Tonawanda casting came without a hole in the first rod pin, it’s definitely a heavy crank. If there’s a hole in the first rod pin, it’s probably a lightweight crank. However, there were a few early 10109865 cranks that had the hole drilled in the rod pin to correct the production process, so having the hole drilled doesn’t always guarantee a lightweight crank.

•The 10055480 Romulus crank came both ways, too. If it has a hole in the first rod pin, it’s the lightweight version, and if it doesn’t, it’s always a heavy crank.

The heavy cranks were used in all of the engines without a balance shaft and in all the VIN “Z” balance shaft motors with the heavy pistons, including the ’95 “second design” versions. The lightweight cranks were used with the lightweight pistons in the ’92-’98 VIN “W,” the ’95 VIN “Z,” “first design” engines, and in the ’96-’98 VIN “X” engines. Using the right crank in the right engine will help prevent balance problems out in the field.

However, you should also be aware that all of these engines are externally balanced with various combinations of flywheels/flexplates and dampers for balance, and that they are “trimmed” at the factory after the hot-run test by pounding balance weights into the holes that are already drilled in the damper. So, if you build them right and still have a shaker, the customer will have to add or subtract weight from the damper and/or flywheel/flexplate in order to get it right.

There is one other subtle difference in the cranks, too. Any of the engines that were installed in ’96 or later and all of the ’95 “S” and “T” trucks with OBD II, including all of the Olds Bravadas, any Blazer with California emissions, and about 10% of the Blazers with federal emissions, had a reluctor wheel installed in front of the crank gear for a crank position sensor that was a part of OBD II. The raised, machined area on the snout is about .100″ longer on these cranks than it was on the earlier ones so the reluctor wheel has a slight press fit. Be sure to sort out the 10105865 and 10055480 cranks with this longer, machined step and save them for the engines that have the crank position sensor.

RODS

There are four different rods in two different weights that come from two different engine plants, so there’s plenty of room for confusion, but it all works out if you follow these two rules:

Rule 1: Keep similar rods in sets by both appearance and weight;

Rule 2: Use only Romulus rods with Romulus cranks.

Then, the question is, how do you tell them apart so you can follow the rules? Start by sorting them by engine plant based on the shape of the balance pad on the big end. If the rod has a cast pad that’s only machined on the face, it’s a Tonawanda rod. These rods don’t have a forging number and may or may not have a dot on the shank. See photo.

If the weight pad on the big end is long and narrow and has been machined on all five surfaces including the sides, the ends and the face, it’s a Romulus rod. All of these rods will have an 818 or 045 forging number on the shank so they’re easy to identify.

After you have separated the rods by source, sort them by weight and put them in sets. The lighter ones will weigh around 662 grams, and the heavier ones should weigh about 675 grams.

The light and heavy rods can be interchanged in engines in sets, but it’s best to use the Romulus rods only on Romulus cranks because you may end up with a ticking noise if they are used with a Tonawanda crank. The Romulus rods have a wider face adjacent to the parting line that can hit on the side of the split pin rod journal, so the Romulus cranks are machined to provide additional clearance for the rods.

The Tonawanda cranks aren’t relieved in this area, so there can be light interference and a noise problem. The Tonawanda rods have the narrower face at the parting line so they can be used with either crank.

PISTONS

There have been five different pistons used in the 262 along with two versions of the lightweight piston.

1) The original, heavy piston used in the 262 was the same as the one that was used in the 350 V8 except that the pin boss was opened up slightly for the offset rod. It weighed about 745 grams with the pin and had a 9.1:1 compression ratio. It was used in all of the light duty engines without the balance shaft from ’85 through ’94 and in the VIN “Z” balance shaft motors from ’93 through part of ’95.

The parts catalog identifies the ’95 VIN “Z” engines with this heavy piston as the “second design” version even though they were built during the first part of the year. They will have one of the following engine codes: ALH, ALA, ALB, ALC, ALD, ALF, ALH, ALJ, ALL, ALP, ALS, AJS, AJT, AJW and AJU.

2) The lightweight piston weighs about 675 grams with a pin. It was used in all the high output, balance shaft engines (VIN “W”) from ’92 through ’98 and in all the VIN “X” engines from ’96 through ’98. It was also used in the “first design” VIN “Z” engines that were built during the latter part of model year ’95, including those with the following engine codes: AAB, AAC, AAF, AAJ, AAK, AAL, AAP, AAS, AAW, AFC, AFD, AHC and AHD.

The lightweight piston was originally a Mahle, full-round design (p/n 2753), but GM switched to its own “RPM” (Revised Permanent Mold) design with a short slipper skirt and a narrower pin boss in ’95. Both of these pistons have very short skirts, so the clearance must be right or they tend to make noise at startup.

3) There was a heavy duty engine offered for trucks and vans with over 8500 GVW from ’89 through ’95. It used a heavy duty, Zollner piston that had an 8.3:1 compression ratio and weighed the same as the regular heavy piston.

4) There was also a high output, VIN “B” (LU2) engine offered in the Astro van in ’90 and ’91. It used a special, hypereutectic, strutless piston that is available from GM under p/n 10181389 in standard, or from Zollner as a H-8269-D. It weighs about 745 grams, just like the rest of the heavy pistons.

5) There was one more piston used in the 262. It’s a low compression (8.6:1), strutless, hypereutectic piston with a deeper dish that was used in the turbocharged Syclones and Typhoons from ’91 through ’93. The OEM standard piston is p/n 12508702 and the Zollner number is a H-8269-E.

All of these pistons are specific to the application, so they should not be interchanged. Building an engine with pistons that have the wrong weight or compression ratio will guarantee a comeback, so it’s better to play by the book.