Internal/external balancing question
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Pro
Joined: Feb 2003
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From: Carlisle Pa.
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Internal/external balancing question
I have a 85 Corvette (autocross only) with a 96 carbureted small block in it. The engine has a one piece rear seal. It has a balanced flywheel and a neutral balanced dampener. I am running a 4 speed muncie transmission. None of these parts actually came together, but the engine runs well with no apparent vibrations
several questions:
1. I this an externally balanced engine?
2. If so, are the flywheel and dampner both balanced?
3. If I change over to a ZF transmission, do I have to change the flywheel, If so, is the ZF flywheel externally balanced?
Your help is appreciated.
Dave
several questions:
1. I this an externally balanced engine?
2. If so, are the flywheel and dampner both balanced?
3. If I change over to a ZF transmission, do I have to change the flywheel, If so, is the ZF flywheel externally balanced?
Your help is appreciated.
Dave
Thread Starter
Pro
Joined: Feb 2003
Posts: 743
Likes: 257
From: Carlisle Pa.
2025 C1 of the Year - Unmodified Finalist
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This is not an LT1 engine. Is the dampener always externally balanced when the flywheel is externally balanced?
Burning Brakes
Joined: Nov 2001
Posts: 1,189
Likes: 2
From: Austin TX
It's going to be hard to tell what you have unless you know it's all factory stuff, in which case your flywheel is counter-balanced since you have a 1-piece rear seal crank. If you take your old and new flywheel to an engine shop that does balancing they can likely "match" them.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
the later model 1 piece rear main seal small blocks the dampener is nuetral balanced and the flywheel is counterweighted. This is because the 1 piece rear seal crankshafts can no longer accomodate the additional small counterweight that was part of the flywheel flange of the older 2-piece style cranks..
People get confused , believing the counterweight on the 2 pce crank is "external" to the engine therefore it has external balance.
The factory considers the crank assembly internal to the engine so in your case the weight on the flywheel is a external balance.
As noted all SBC are neutral at front EXCEPT 400.
From the factory
2 pce engines are neutral rear balance
1 pce engines are external rear balance
