Bottom end differences between LT-1 and Gen 1?
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 1,228
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From: Dallas Texas
Bottom end differences between LT-1 and Gen 1?
I've been searching the net for a while and I can't seem to find anything that clearly states the difference between LT1 and 1pc rear main Gen 1 SBC bottom end components. Will Gen 1 SBC cranks not work in an LT1 block? Is there a simple modification to make them work? The reason I ask is because while crusing ebay looking at forged Eagle stroker cranks, I have come across different p/n for each.
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 1,228
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From: Dallas Texas
Ok, I found this in Doug Anderson's "Rebuilding the Chevrolet LT-1"
So to me, it seems it is only important to use an LT1 specific crank if a person is buiding an engine that does not want to have the rotating assembly neutral balanced. It would also stand to reason you would have to use a neutral balanced dampner and have the flywheel balanced with the crank when not using an LT1 specific crank, which would be the case anyway if doing a zero balance.
The crank for the LT1 looks just like the one in the late 350 and has the same casting number 14088526, but it’s balanced for the lightweight pistons that were installed in the LT1. Be sure to keep these cranks separate so they don’t end up in a regular 350, and don’t ever use a regular 350 crank in a LT1. In fact, if you are short of LT1 cranks and don’t have a balancing machine in your shop, you would be better off using a crank from a 305 instead of a 350 because it’s actually closer to the balance specs for the LT1 crank.
Large Impressive Member
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Obviously if you mix and match components, whether factory, aftermarket or a combination, rebalancing will always be necessary. When I installed even lighter than stock pistons in my LT1, of course I had everything balanced. The good thing is that it allowed weight to be removed from the crank. The whole rotating mass was a few pounds lighter when finished, I forget exactly how much now. My new stroker will be assembled with light stuff too. I like light stuff! 
Le Mans Master
Joined: Apr 2000
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From: Manassas VA
I find it hard to believe that GM would use the same casting no. and then balance differently. This would make for a nightmare on buying a rebuilt crank. Not saying its not true, just hard for me to believe.
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Large Impressive Member
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by 93 ragtop
I find it hard to believe that GM would use the same casting no. and then balance differently. This would make for a nightmare on buying a rebuilt crank. Not saying its not true, just hard for me to believe.
Thread Starter
Burning Brakes
Joined: Jan 2002
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From: Dallas Texas
Originally Posted by 93 ragtop
I find it hard to believe that GM would use the same casting no. and then balance differently.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
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From: Manassas VA
The highlighted parts are what I have a hard time believing.
The crank for the LT1 looks just like the one in the late 350 and has the same casting number 14088526, but it’s balanced for the lightweight pistons that were installed in the LT1. Be sure to keep these cranks separate so they don’t end up in a regular 350, and don’t ever use a regular 350 crank in a LT1. In fact, if you are short of LT1 cranks and don’t have a balancing machine in your shop, you would be better off using a crank from a 305 instead of a 350 because it’s actually closer to the balance specs for the LT1 crank.
A casting no. is used to identify a part. IE: a head casting no. will be used for identifying the valve size, combustion chamber size etc. If any design changes were made the casting no. is changed.
If GM did this, they really screwed up.
The crank for the LT1 looks just like the one in the late 350 and has the same casting number 14088526, but it’s balanced for the lightweight pistons that were installed in the LT1. Be sure to keep these cranks separate so they don’t end up in a regular 350, and don’t ever use a regular 350 crank in a LT1. In fact, if you are short of LT1 cranks and don’t have a balancing machine in your shop, you would be better off using a crank from a 305 instead of a 350 because it’s actually closer to the balance specs for the LT1 crank.
A casting no. is used to identify a part. IE: a head casting no. will be used for identifying the valve size, combustion chamber size etc. If any design changes were made the casting no. is changed.
If GM did this, they really screwed up.
Advanced
Joined: Feb 2006
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From: Reading Pa
LT1/4, L98, L99 cranks all physiclly interchange. The difference is in balancing. I even put a L99 3.00 stroke crank in a L98 block and made a 450 HP 302. I had the crank preped right and balanced with 6.25' rods and forged pistons and with the flywheel and damper. All swaps must be balanced for piston/rod/flywheel combos and must be balanced as a set.
Team Owner
Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Originally Posted by kopbet89c4
L98s only came as a 2 bolt main and an LT1 came as either a 2 bolt or 4 bolt main.
thats L98 corvette parts, L98 camaro is a 4-bolt
Race Director
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From: The Top of Utah
Originally Posted by 93 ragtop
A casting no. is used to identify a part. IE: a head casting no. will be used for identifying the valve size, combustion chamber size etc. If any design changes were made the casting no. is changed.
If GM did this, they really screwed up.
If GM did this, they really screwed up.
A casting number merely identifies a CASTING. Once cast, it is possible to machine that casting into multiple parts and therefore part numbers. You've never heard of both 2 and 4 bolt main blocks having the same casting number?
Speaking of two and 4 bolt mains. Either block takes the same crankshaft.
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