complete history of the 4.3 liter with casting numbers

[Scott Danforth]

thought I would post the complete history of the 4.3 liter that I could find. These are links and articles that I have bookmarked for my own use, however they should help many people. it may help some people when looking for parts or sourcing a salvage yard motor or a reman. keep in mind that this history is for engines out of both the Romulus plant and the Tonawanda plant. Industrial and Marine motors typically only come from the Tonawanda plant



Mercruiser GM V6 sterndrives
Model SN Year Note
4.3L2 B787205-B917529 1988 4.3 liter, 1-piece RMS non-balance shaft SeaRay only
4.3L4 B785981-B921276 1988 4.3 liter, 1-piece RMS non-balance shaft SeaRay only


185 (4bbl) 6330183-6919655 1983-1984 3.8 liter, 2-piece RMS
185 (2bbl) A331455-B527954 1985-1987 4.3 liter, 1-piece RMS
205 (4bbl) A331455-B527954 1985-1987 4.3 liter, 1-piece RMS w/ 4 bbl
205/4.3LX (4bbl) B527955-D714369 1987-1991 4.3 liter, 1-piece RMS non-balance shaft
175/4.3L (2bbl) B527955-D714106 1987-1992 4.3 liter, 1-piece RMS non-balance shaft
4.3L (Gen II 2bbl) D714107-F000877 1992-1993 4.3, 1-piece RMS w/ balance shaft
4.3LX (Gen II 4bbl) D714370-F001219 1992-1993 4.3, 1-piece RMS w/ balance shaft
4.3L (Gen II 2bbl) F000878-F601126 1993-1995 4.3, 1-piece RMS w/ balance shaft
4.3L (Gen II 2bbl) F601127-F000878 1996 4.3, Last of non-vortec in the pipeline
4.3LX (Gen II 4bbl) F601127-F802999 1996 4.3, Last of non-vortec in the pipeline
4.3L (Gen+ 2bbl) F803000-K999999 1996-1997 4.3, 1-piece RMS, Vortec heads
4.3LX (Gen+ 4bbl) F803114-UP 1996-1997 4.3, 1-piece RMS, Vortec heads
262 Mag (TBI Gen+) F803000-K999999 1996-1997 4.3, 1-piece RMS, Vortec heads
4.3LH (Gen+ 2bbl) L010044-UP 1998 4.3, 1-piece RMS, Vortec heads
4.3L (Gen+ TBI) L012009-UP 1998-UP 4.3, 1-piece RMS, Vortec heads


Volvo Penta GM V6

The serial and engine number can tell us a lot about you Volvo Penta marine engine. Some owners have difficulty identifying the exact model of their engine or the year it was produced, while the answer was coded inside the serial number and engine identification all along.
But the current identification method was not always the same. Engines produced prior to 1993 were painted red. The serial number was different than the ones on the modern engines. First of all, the serial number had a prefix meant to tell you if the engine is inboard or sterndrive or inboard/outboard drive. Inboard engines were marked with MB or BB, while sterndrive engines were marked with AQ.
Next, the serial number would feature a horsepower rating number or a displacement. Finally, the serial number would contain a letter which indicates the year of production and the production version. So if the serial number looked like this AQ125B, we would know that your engine was sterndrive engine with a 131 shaft HP and its year of production was either 1986 or 1987

The later models in this series (early nineties) changed to a system based on displacement. Engine models had a three-digit number followed by a letter. For example, the 43 in 430 signifies that the displacement is 4.3 liters and the third digit is for model control. A 434 and a 432 are both 4.3 litter engines but the different third digits indicates a difference between the two engines. Volvo manufactured this family of engines until 1993.
Incidentally, from 1993 to 1998 or so Volvo supplied both engines and sterndrives to OMC. The drives were branded OMC Cobras but were really manufactured by Volvo. These engine models had a two-digit number and followed by a string of letters to identify the year and model. For example a4.3GLPNCA is 4.3 litters, and the:
G identifies that it is a General Motors block,
L tells you that it is limited output. L= limited, S= Superior, X= exceptional i = stands for fuel injection (the lack of and “i” means that it is carbureted)
P tells you that it has power steering,
NC identifies that it is a 1996 model year and
A is the service code for version control.
The fourth and fifth (or fifth and sixth) letters always identify the year of the particular engine in question. The year codes for different years is as follows:
MD = 1993-1994
HU = 1994-1995
NC = 1996-1997
BY = 1997-1998
WT = 1998-1999
EF = 1999-2000
From model year 2000 and up, engines were again painted red in color, and the identification methods changed. The first two numbers is now the displacement followed by a letter, which indicates the supplier of the engine block. For Ocean Series, this letter is replaced with OS and indicates it can be used with Ocean Series outdrives. One or two letters identifying the fuel system and the output (lower case i stands for fuel injection) follow the supplier ID. It should also be noted that the 3.0 will also have a letter that identifies the steering method M for manual and P for power. For example, we have a 5.7GXi-A. We know that this engine has a 5.7 liter displacement, that GM supplies it, and that is has an exceptional out put with fuel injection (Xi). We also know that this is the A version which is the first version for this engine which would come before the gxi-b or –c, but is not indicative of a specific year of production.

OMC GM V6



Need to put something here someday







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 (TBI).

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 uner 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, GM 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 chevrolet. 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
Chevrolet 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.

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.

 

[Scott Danforth]

RODS
There are four different rods in two different weights that come from two different engine plants, so theres 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 thats only machined on the face, its a Tonawanda rod. These rods dont 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, its a Romulus rod. All of these rods will have an 818 or 045 forging number on the shank so theyre 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 its 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 arent 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. Its 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 its better to play by the book.


BALANCE SHAFTS
Any 90 V6 creates some strong, primary imbalance forces, especially in the vertical mode. The 262 is no exception. GM originally underbalanced these engines by putting about 46% on the bobweights instead of the usual 50%. This reduced the vertical imbalance that was trying to lift the engine up off the mounts, but created a strong horizontal imbalance that shook the engine from side-to-side instead. So, in order to eliminate a lot of the "noise, vibration and harshness" in the engine and make it into a world-class motor, GM added a balance shaft to the premium engines in 92 and included it in all of them by 95.

There are two balance shafts, a light one and a heavy one, and two versions of the light one. See photo. The light one is either a 10224542 or a 10172748 casting that comes with or without a metal wear sleeve installed on the back journal, depending on the application. The wear sleeve was used on the lightweight balance shaft when it was installed in a 92 "first design" engine with the needle bearings in the back, but it wasnt used when the lightweight shaft was installed in the "second design" engine that had a bushing in the back of the block.

This "first design" shaft should not be used in a "second design" engine because the wear sleeve shortens the surface area needed for the bushing. These lightweight shafts were installed in all of the engines that had the light pistons including the 92-98 VIN "W," the 96-98 VIN "X" engines and the "first design" VIN "Z" engines in 95 that were built with the lightweight pistons.


The heavy balance shaft is either a 10224541, a 10105902 or a 12550286 casting. It can be visually identified by the raised identification band around the middle of the shaft. It was used in all the 93-94 VIN "Z" balancer engines and in the 95 "second design" VIN "Z" balancer engines with the heavy pistons. The heavy balance shaft weighs about 125 grams more than the light one, so it shouldnt be interchanged with the lighter one.

The balance shafts rotate at engine speed and are gear driven off the front of the cam. There are two different gear sets, one with "wide" teeth and one with "narrow" teeth. The ones with the "wide" teeth were used in the "first design" engines along with the needle bearing balance shaft. Some of these early balance shaft engines had a whine to them, so the gears were modified at the same time the block was changed over to the "second design" version with the sleeve bearing in the back. We recommend using only the "second design" gears to help avoid any possible noise problems.

CAMS, LIFTERS, TIMING GEARS
Several cams have been used in the 262. There are important differences in both the specifications and the base circle diameter.

1985-86: The same flat tappet cam was used in 85 and 86.

1987- 91 VIN "Z": The original roller cam used for the throttle body motor was a 10088148 or a 14093686. It had a 1.380" intake base circle, a 1.335˝ exhaust base circle, and a pretty mild grind.

1990-91 VIN "B": The H.O. motor had a much hotter cam that should not be interchanged with any other application. Its a p/n 10055487.

1992-94 VIN "Z" WITHOUT BALANCE SHAFT: The specs for this cam were comparable to the earlier VIN "Z" cams, but the base circle on both the intake and exhaust was reduced to 1.260˝. The OEM part numbers are 10144176, 10214713 and 10172776.

1993-95 VIN "Z" WITH BALANCE SHAFT: The specs on this cam were similar to the ones used in the VIN "Z" without a balance shaft, but a snout was added for the balancer drive gear. Its a p/n 10144065.

1992-95 VIN "W" WITH BALANCE SHAFT: The premium high output engine came with central fuel injection, a balance shaft and a better cam starting in 92. The original cam, p/n 10144047, was used from 92 to 94. It was replaced by p/n 10241693 in 95. They are comparable grinds so most rebuilders are interchanging them.

1996-98 VIN "X" WITH BALANCE SHAFT: The VIN "X" engine replaced the VIN "Z" in 96. It is identical to the 96 VIN "W" engine except for a milder cam and 10 less horsepower. The cam is a p/n 10241692.

1996-98 VIN "W" WITH BALANCE SHAFT: The VIN "W" engine has a 10541691 camshaft and makes 10 more horsepower than the VIN "X" engine. There is also a special roller cam for the VIN "Z" turbocharged engines (p/n 10214714) along with a couple more with a fuel pump lobe for marine and industrial applications, but these are the common ones that were used in most of the cars and trucks. All of these cams can be identified by the last three digits of the part number that is stamped on the barrel of the cam, just behind the last lobe and in front of the distributor gear.

Matching the right cam with the right lifter and adjusting the valves correctly is important in order to avoid noisy lifters at startup, a problem thats commonly known as "morning sickness." Prior to 92, the 262 had the traditional adjustable rockers that had been used on all of the small block Chevys for years. The cam had a 1.380"/1.335" base circle and used a short-travel lifter. Turning the rocker nut one turn gave the lifter a .040" preload and put the plunger in the middle of its travel.

In 1992, when Tonawanda switched to a "net lash," non-adjustable valvetrain; the base circle was reduced to 1.260" on all of the cams, and a lifter with more travel was used across the board, apparently to provide more latitude for manufacturing tolerances with the "net lash" rockers. (Note: The Romulus plant did not switch to "net lash" until 95). Unfortunately, this combination can cause noise problems in the field because it takes longer for the lifter to refill at startup when it has bled down overnight, unless the preload is set at .080".

This problem can be cured by turning the rocker nut two turns with the adjustable rockers, but that cant be done with the "net lash" setup, and its contrary to everything everybody knows about setting the valves on a Chevrolet, too. The best approach requires the replacement of the "net lash" studs with a set of special conversion studs that have metric threads on the bottom, along with 3/8" threads on the top, and using them along with the short lifters that are preloaded one turn.

If you prefer to rebuild the engines as they came and use the longer lifters with the adjustable rockers, increasing the preload to two turns will help avoid "morning sickness." Carefully controlling the stem heights and clearances with the "net lash" rockers will help ensure that you have enough preload to avoid noisy lifters most of the time.

Just for the record, theres one extra benefit to switching to the short lifters and the adjustable valvetrain on everything; you can disregard the base circle issues and consolidate more of the cams.

There are two cam thrust plates used for the roller cam engines. The one for the non-balancer engines that are smooth on both sides are available under either p/n 14093636 or p/n 10088128. The thrust plate for the balancer engines is smooth on one side and has four radial grooves on the other side. Its a p/n 10144059.

GM has used three different timing gears for the 262 since 85. The flat tappet engines used a p/n 340235, the non-balancer, roller cam engines had a p/n 12552128 and the balancer engines used a p/n 10144121. They are not interchangable.

CYLINDER HEADS
There have been several cylinder heads used on the 262 since it began in 85. Some of the changes appear to be minor, but most of them will create problems if the wrong head is used in the wrong place. Heres an overview year by year:

1985-86: The 1985 and 86 engines used a 14079248 casting. It had two holes on one end and three on the other end.

1987-91 TRUCK, EXCEPT HEAVY DUTY AND 87-93 CARS: These heads were the same as the earlier ones except that they had three bolt holes on both ends. The intake surface above the ports was quite narrow; its only about 0.250" wide. The unmachined, cast ledge on the top edge of the head was 0.600" wide. Look for c/n 14094768, 10144103, 14099067 or 12553050. All of these heads had adjustable rockers.

1992 TRUCK WITH TBI AND NO BALANCE SHAFT: These heads had a wider surface for the intake gasket even though they didnt need it because all of the tooling was changed to accommodate the new heads for the VIN "W" CFI engines that were introduced in 92. The 10144103 casting was carried over from 91, but it had the wide intake with straight ports on the top. It can be used along with any of the earlier 14094768, 10144103, 14099067 or 12553050 castings from 87 through 91.


1992-93 TRUCK WITH CFI, BALANCE SHAFT: When the high output VIN "W" engine with central fuel injection was introduced in 92, the heads were redesigned for the application. They had "eyebrows" added to the top of the intake ports to make room for the injector nozzles, so the intake surface above the ports was increased by 0.250˝ for improved sealing, and the cast ledge above it was narrowed down to 0.350˝ to provide more room for the intake manifold.

The 10077626, 14099064, 10240209 or 10238181 castings were used, but be sure to check them over carefully because there are two versions of the 10238181 and 10240209 castings with an important difference. In 92 and 93, they came with an 8 top angle on the intake seat and a 75 throat, but that was changed to a 30° top angle with an 80° throat in 94. Separate the 8 heads from the 30 heads and use them only on the 92 and 93 engines.

Tonawanda switched to "net lash" rockers in 92, so some of these are adjustable and some arent.

1993 TRUCK WITH TBI, EXCEPT HEAVY DUTY: The intake manifold on the TBI motor was modified in 93 to take advantage of the wider intake surface that was machined on the 92 and up heads, so these engines must have the heads with the wide intake and should use the castings with the 8° top angle on the intake seat.

1994-95 TRUCK WITH TBI OR CFI, EXCEPT HEAVY DUTY: The top angle for the intake seat was changed from 8 to 30 and the throat was opened up from 75 to 80 to give a 10% increase in intake airflow for better performance in 94. The same heads were used on both the TBI and CFI engines through 95.

Both the 10238181 and 10240209 castings were used, but they have to be visually sorted because the early ones with the 8° seat probably shouldnt be used on the 94s and 95s. If you do decide to stretch the rules and use the 93 heads on a 94-95 engine, be sure to use them in pairs. Some of the 94s still had adjustable rockers because Romulus didnt switch over to "net lash" until 95.

1996-98 ALL TRUCKS EXCEPT HEAVY DUTY: There was another all new head introduced in 96. It had bigger intake and exhaust ports, no exhaust crossover and four angled bolts for the intake. Its the 10235772 casting that was used up through 98.

1989-95 HEAVY DUTY TRUCK WITH TBI: There have been three different heads used on the heavy duty 262 since 89.

1) 1989-92: The original head, c/n 14099066 was used up through 91. The 10144115 casting with the wider intake surface showed up in 92 even though the narrow one still worked. Both of these castings are interchangeable.

2) 1993: The 14099070 casting came with an 8 top angle on the intake seat in 93, but it was also available with the 30° top angle in 94 and 95. Sort them accordingly and use them in pairs.

3) 1994-95: The 14099070 casting with the 30 top angle for better airflow should be used on the 94 and 95 engines. Be sure to use them in pairs. See photo.

All of these heavy duty heads had hard donut seats, replaceable guides and heavy duty exhaust valves with 3/8" stems.

1991-93 SYCLONE AND TYPHOON WITH TURBOCHARGER: The turbo motors used the same heads that were installed on the VIN "Z" throttle body motors. It appears that they came with the narrow intake surface all the way through 93. Look for the 14094768, 10144103 and 1409967 castings.

KNOCK SENSORS
Beginning in 86, some of the 262s had fuel injection, and by 87 all of them were fuel injected and computer controlled, so they had either one or two knock sensors. Its almost impossible to know whether the engine came with one or two and where they were located, because it varied by year, model, engine and application.

The sensor has been installed in the top or bottom hole in the left head, in the bottom hole in the right head, in the back of the block or in the back of the right head. The wiring harness will not reach if the sensor is in the wrong location and that the sensors cant always be interchanged because some of them have tapered pipe threads and others have metric threads.

So, it comes down to practicing damage control by building all of these engines with a fail-safe combination like this:

Drill and tap every block for a metric knock sensor.

1987-92: The left head must have two holes with at least one wet hole on the bottom. The right head must have at least one wet hole in the bottom location.

1993-95: The left head must have two wet holes. The right head must have at least one wet hole in the bottom location.

You may have to drill some that came with a dry hole on the top and convert others by drilling and tapping a second hole in order to have enough heads. Check to see if the casting is thick enough before drilling it. Some of them like the 10077626 dont have the pad so they cant be converted, but others like the 14099064 can be drilled even if the second hole isnt there. It may take some extra time, but using one of these combinations will avoid all kinds of problems in the field.

REBUILDING TIPS
Rebuilding these engines is pretty straightforward. The blocks seldom crack, except some of the 10227196 castings, and the heads are usually good. The cranks are another story, though, with about 30 percent down on at least one rod journal, usually toward the front of the crank. Cam mortality can be a problem, too, with up to 20 percent of the roller cams needing replacement. There are some other areas that can cause problems, too:

OIL PUMPS
From 85 through early 93, the 262s used the regular small block oil pump with the 0.620" (5/8") hole for the pickup tube. In mid-93, the pump was changed because the pickup tube was enlarged to 0.742" on the "S" and "T" trucks. After 93, all of the engines used the pump with the big hole.

PICKUP TUBES
There are several different pickup tubes used, depending on the application, and there are two different diameters, depending on the year and application. Be sure to check it out carefully and match them up at the sales counter if at all possible.

WATER HOLES
The intake gaskets may have the rear water holes open or restricted, depending on the application. The holes are always open on the carbureted truck engines and boat engines, but they may or may not be open on the injected engines. When the blocked gaskets are installed correctly, there will be two small tabs sticking out from the front of the intake. If they are installed backwards, the tabs will not be showing and the engine will overheat because there is no circulation.

CONCLUSION
Thats the story on the 262 and the changes that have been made over the years. It all makes sense when you see it in the perspective of time, but these engines can still be a handful to catalog and build. Just treat it like its a part of the small block family, and youll know what goes where and how it all fits together.

 

[Scott Danforth]

Below is from a GM news bulletin

http://media.gm.com/media/us/en/gm/...es/news/us/en/2015/feb/0212-marine-gen-v.html
GM Marine?s New ?Gen V? Engine Has History on its Side
60-year development legacy yields durability with greater power, efficiency
2015-02-12

GM Marine?s new 4.3L V-6 Small Block engine for sterndrive applications is a lightweight, technologically advanced and efficient performer designed to deliver excellent performance while using less fuel than many V-6 marine engines.
It is based on the fifth generation of General Motors? legendary Small Block architecture, which was introduced 60 years ago and powers through the 21st century with advanced performance- and efficiency-optimizing technologies, including variable valve timing and direct fuel injection.
?The Small Block was adapted for marine use soon after it was introduced and we have worked for decades with marinizers to refine the engine family for the unique requirements of powerboats,? said Gary Halligan, GM Marine engineering.
?The new Gen V Small Block architecture represents an unprecedented investment in engine design, which leveraged the depth and breadth of GM?s powertrain resources to bring to the market one of the most efficient, powerful and technologically advanced engines in the marine industry.?
The new Gen V 4.3L V-6 shares the same design attributes as the Small Block engine family found in the latest Chevrolet Silverado, Tahoe and Suburban trucks and SUVs, as well as the high-performance Corvette Stingray.
?Allowing the marine industry to take advantage of proven automotive technology is a win for the boating world,? said Patrick Koenigknecht, GM director of Marine Original Equipment sales. ?Direct injection and continuously variable valve timing technologies are perfect for the marine industry because they result in more power and better fuel efficiency ? and the customer benefits from factory-proven reliability and durability built on years of tough truck engine design, development and testing.?
Volvo Penta is a marinizer already working with the new Gen V engine.
?We?ve trusted GM engines for years and want to get the latest technology to the customer as soon as possible,? said Ron Huiber, president, Volvo Penta. ?We believe this new engine will help transform the boat industry with its great balance of power and efficiency ? and the durability customers have come to rely on for decades.?
Advanced combustion system drives performance, efficiency
The power and efficiency of the GM Marine Gen V marine engine are due to an unprecedented level of analysis, including computational fluid dynamics, to make the most of the combustion system and the direct injection fuel system and variable valve timing systems that support it. More than 10 million hours of computational analysis were conducted on the engine program, including 6 million hours (CPU time) dedicated to the advanced combustion system.
Direct injection is new to the engine architecture ? and marine engines ? and is a primary contributor to its greater combustion efficiency by ensuring a more complete burn of the fuel in the air-fuel mixture. This is achieved by precisely controlling the mixture motion and fuel injection spray pattern, including pistons that feature uniquely sculpted topography to precisely direct the fuel spray for a more complete combustion. Direct injection also keeps the combustion chamber cooler, which allows for a higher compression ratio ? which supports greater power.
Continuously variable valve timing, which GM pioneered for overhead-valve engines, further enhances performance, efficiency and reduced emissions.
Additional engine features:
All-aluminum block and oil pan: Lighter than conventional cast iron, the aluminum cylinder block and heads of the Gen V engine help reduce the boat?s overall weight, enhancing performance and efficiency. The Gen V block was developed with math-based tools and provides a light, rigid foundation for an impressively smooth engine. Its deep-skirt design helps maximize strength and minimize vibration. Its bulkheads accommodate six-bolt, cross-bolted main-bearing caps that limit crank flex and stiffen the engine?s structure. The block also features nodular iron main bearing caps, which represent a significant upgrade over more conventional powdered metal bearing caps. They are stronger and can better absorb vibrations and other harmonics to help produce smoother, quieter performance.
Advanced oiling system: The oiling system is driven by a new, variable-displacement oil pump that enables more efficient oil delivery. Its dual-pressure control enables operation at a very efficient oil pressure at lower rpm and delivers higher pressure at higher engine speeds to provide a more robust lube system for the high-rpm engine operation that?s characteristic of powerboat operation. Standard oil-spray piston cooling sprays the underside of each piston and the surrounding cylinder wall with an extra layer of cooling, durability-enhancing oil. For optimal efficiency, they are used only when needed the most such as start-up, giving the cylinders extra lubrication, and at higher engine speeds.
Positive Crankcase Ventilation-integrated rocker covers: One of the most distinctive features of the Gen V engine is its domed rocker covers, which house an integrated positive crankcase ventilation system that enhances oil economy and oil life, while reducing oil consumption and contributing to low emissions. The rocker covers also hold the direct-mount ignition coils for the coil-near-plug ignition system. Between the individual coil packs, the domed sections of the covers contain baffles that separate oil and air from the crankcase gases.

 

[alldodge]

Good write up Scott, have copied and pasted it into a Word doc with you as Author. I'm ready for small block V8's now thanks

 

[Scott Danforth]

Good write up Scott, have copied and pasted it into a Word doc with you as Author. I'm ready for small block V8's now thanks

Thanks Bob

how far back in the SBC history do you want me to go....LOL

I was thinking of doing the BBC first. however where do you stop, at stock GM stuff, or move into the aftermarket as well.

I only gathered the stuff together. I had it bookmarked when I was building a frankenmotor 4.3 a while back

 

[alldodge]

To me its all helpful including BBC, I like having it all. Sure BBC would be more important to me these days, but I have links all over the place just tracking down things. So if your willing to provide a one stop place I'm all ears

 

[muskyfins]

Sticky worthy for sure :thumb:

 

[Scott Danforth]

I think we would need to have a mod or two help throw some information into the bucket

 

[Alumarine]

Great info, thanks!

 

[Maclin]

Lots of great reference detail, well arranged, nice!

 

[Scott06]

Does anybody know why they went to a 'metric' block? Repowered a boat that had a 2003 vintage 090 casting 4.3 with a 5.0, swapped all the accessories, mounts, flywheel cover, starter, wire harness, etc. motor mount, flywheel cover, starter bolts on the 4.3 were metric, all other fasteners were SAE. Same bolts on the 5.0 were SAE. Mix and match on same block is goofy

 

[RandyJ]

I would love some updated information on 4.3 vortec since 1998. I mixed and matched a 2000 tonawanda with a 2011 Romulous. The block, heads, crankshaft, piston rods all original tonawanda. I swapped a couple of valves from the Romulus to tonawanda. Intake, carburetor, and cam from Romulus. The big difference I could see in the engines was 2000 tonawanda has a plastic timing cover but the 2011 Romulus had an aluminum timing cover. Otherwise the only difference I noticed was cam bearings being specific for either engine. The tonawanda was bored .030 over so it does have new pistons. I'm wondering if there are other differences that may cause problems.

 

[Fun Times]

6 Cylinder | PerfProTech.com

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NEW PART NUMBERS FOR V6 LONGBLOCKS | Service Bulletin | Crowley Marine

08-OCT-2007 - Manufacturer Service Bulletin: NEW PART NUMBERS FOR V6 LONGBLOCKS

www.crowleymarine.com