Stock Crank

[BLACK92TY]

I'm at work and don't have much time to do a search. But basically we're doing a rebuild on the stock motor. Crank was magnafluxed and found it it's got some cracks.

Is there anything fancy about the sy/ty cranks? Will a regular 4.3 crank work? How much cash are we talking here?

Thanks in advance,
Jon

 

[#2875]

Re: Stock Crank

it was a while ago but i think i paid $150 for a 10/10 crank from the auto parts store. there are guys making 700hp on the stock crank. you can have it cryoed or nitrided if you want to go a step further.

I'm at work and don't have much time to do a search. But basically we're doing a rebuild on the stock motor. Crank was magnafluxed and found it it's got some cracks.

Is there anything fancy about the sy/ty cranks? Will a regular 4.3 crank work? How much cash are we talking here?

Thanks in advance,
Jon

 

[BLACK92TY]

Re: Stock Crank

Will any old 4.3 crank work?

 

[midnightbluS10]

Re: Stock Crank

SyTy's used a stock 4.3L crank.

Rebuilding the New Chevy 4.3L(262), Doug Anderson, Automotive Rebuilder, April 2000

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.