Stephen68

Hey everyone, i need to know if they actually make a replacement crankshaft that does not need to be balanced to rod and piston setups? I bought this crank and was told by the mechanic that it does not need to be balanced because it is a stock replacement??? Is there any truth to his statement?

SCA 9-10526 NEW SBC SCAT 350 CRANKSHAFT SB CHEVY GM VORTEC 1 PIECE REAR MAIN

shoebox

As I recall, LT1s are balanced a little differently than the standard SBC, because they had lighter pistons. Unless it is a crank out of another LT1, I would have it balanced.

Stephen68

Fred, i wish to goodness i would have asked you guys first...Its already installed and like i said, the garage that ordered my parts and did my block and heads told me that it did not need to be balanced...Boy, have i learned a lot since i began this build this past winter....Thank ya Sir....

shoebox

You keep calling me Fred. I am Rob.

Stephen68

Dang Rob, i am sorry brother....i dont know where i got that from lol...I do apologize sir....

Injuneer

Is it or isn't it an LT1 specific crankshaft?

See the paragraph on CRANKS in this article:

Rebuilding the Chevrolet LT1 Engine - Engine Builder Magazine

Stephen68

Rob, according to what i read and what the mechanic told me it is an after market OEM replacement crank by Scat. The cranks counter weights are drilled so some type of balancing has been done but whether its correct or not i don't know....Maybe you know better than me but i will read your link...Thanks again!

shoebox

He's not Rob, he's Fred.

Maybe you will be alright. It's a little late now to do anything about it. Best case is to have it balanced. That does not mean it might not be ok. Just depends on the situation.

Injuneer

Scat sells a cast steel crank they state is a direct replacement for the LT1. But on the JEG's and Summiti websites, one describes is as internally balanced, and the other as internal/external (LT1 style). Unable to find a clear description of what it is, and people on ebay seem to sell it as a stock replacement for all single rear main small block Chevys, which is not possible.

In retrospect, the stock LT1 crank is probably stronger than the Scat, just needs to be polished and filleted.

Stephen68

Rob and Fred, i apologize for getting your names backwards lol...i will get it straight. As far as the crank, i have ran the car for break in and as of now i can feel zero vibration in the steering wheel as well as using a stethoscope and listening to the motor idle ...I am going to go ahead and treat is as a balanced crank and run it and keep regular maintenance on it...if it doesnt last i have another lt1 i am going to build here, maybe i will stroke it...thanks guys for all the input and next time my complete rotating assembly will be balanced properly beforehand...

Chimera96

if the motor does not vibrate....that would indicate it's "off the shelf balance" is OK for your motor

with that said most would have the crank along with the rotating assembly balanced during the build regardless of advertised claims from the aftermarket part. In this case a Scat crank.

MachinistOne

The stock LT1 crank is stronger than that Scat 9000 junk crank, those things are a PITA to balance, and yes, it has to be done anytime you start out fresh.