LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

383 rotating assembly balance

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Old 03-05-2003, 06:03 PM
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383 rotating assembly balance

Is the crank for a 383 external or internally balanced. I belive it must be externally balanced to the flyweel....Am I correct?
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Old 03-05-2003, 07:25 PM
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I could be wrong but I thought the rotating assembly was internally balanced and the flywheel/damper neutrally balanced.
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Old 03-05-2003, 07:27 PM
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Internally balanced.
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Old 03-05-2003, 07:30 PM
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The front of the crank is neutral balanced, The rear has to be balanced with the flywheel.
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Old 03-05-2003, 08:29 PM
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Originally posted by RCF925
The front of the crank is neutral balanced, The rear has to be balanced with the flywheel.
what he said
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Old 03-06-2003, 04:55 PM
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Originally posted by RCF925
The front of the crank is neutral balanced, The rear has to be balanced with the flywheel.
Thanks, thats what my machine shop said....just wanted to confirm.
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Old 04-14-2003, 01:25 AM
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What does this mean exactly...

If one goes w/ a 383, do they need a new flywheel? I have guys telling me this...
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Old 04-14-2003, 11:46 AM
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Originally posted by Dave88LX
What does this mean exactly...

If one goes w/ a 383, do they need a new flywheel? I have guys telling me this...
No....the rotating assembly just needs to be balanced with your flywheel on it. Now that said...It could take quite a bit of heavy metal added to the crank to get the job done with the stock unit. My machine shop said it is very easy to balance the assembly with one of the aftermarket aluminum flywheels that has removeable wieghts but its not a must have.
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Old 04-17-2003, 09:04 PM
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THey're still telling me I need a 400 flywheel, WTF!
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Old 04-17-2003, 09:41 PM
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The old 383s were made using a 350 block, with a 400 crank and flywheel. LT1's arent done that way. They use an aftermarket crank with your flywheel. Your buddies obviously don't know much about the LT1.
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Old 04-17-2003, 10:38 PM
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Originally posted by BigDaddy
The old 383s were made using a 350 block, with a 400 crank and flywheel. LT1's arent done that way. They use an aftermarket crank with your flywheel. Your buddies obviously don't know much about the LT1.
Exactly what I was looking for, thanks for the info!

So the "balancer" is really just a dampener, and has nothing to do with balance. It's easy to get a LT1 rotating that is already balanced, and all the machine shop has to do is balance the flywheel to the rotating assy? How is this achieved?

Thanks again. I did a search but this was the only thread I could find on balancing.
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Old 04-17-2003, 11:28 PM
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yes the harmonic balancer is really a harmonic dampener. I don't know how machine shops actually do the balancing. I've never seen it done. Maybe someone else could help you out.
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Old 04-18-2003, 12:10 AM
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If the flywheel has weights like a Mcleod then thats how it's balanced, If not you either add weight by welding or take it off at the rear of the crankshaft. I just had mine balanced for a 383 with the Mcleod flywheel but there still wasn't enough weights on the flywheel so they had to add some to rear of crank.
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Old 04-18-2003, 12:34 AM
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I've got a factory flywheel...wonder how it will work out. Thanks for the info!
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Old 04-18-2003, 10:17 PM
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Originally posted by RCF925
If the flywheel has weights like a Mcleod then thats how it's balanced, If not you either add weight by welding or take it off at the rear of the crankshaft. I just had mine balanced for a 383 with the Mcleod flywheel but there still wasn't enough weights on the flywheel so they had to add some to rear of crank.
How much did that cost?
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