Balanced Flywheel???
Thread Starter
Pro
Joined: Aug 1999
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From: Perth,Western Australia,Australia
Balanced Flywheel???
Just like some opinions on an issue about buying a flywheel. Just what does it mean if the engines is internally balanced you do not need to balance the flywheel, so if i do not know if my engine is internally balanced do i need to have the new flywheel that i intend to buy balanced or are they already balanced?
Thanks for any input.
Neil.
Thanks for any input.
Neil.
Safety Car
Joined: Aug 2000
Posts: 3,711
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From: San Antonio TX
The only externally balanced engines installed in a C3 from the factory was the 454 and the Calif-only 305. If the engine has been swapped or had new guts installed -like a 383 stroker- it could be internal or external. If it is internal balance, then you would have a neutral-balance flywheel.
Edit: to clarify this, an internal balance means that all of the considerations for the rotating and reciprocating forces are accounted for on the crankshaft. For an external balance, the opposing forces can not be accounted for on the crankshaft alone (technically, most of the time it can but it becomes a rather expensive affair with the many slugs of Mallory metal needed to achieve this). Whatever flywheel you buy, if the engine is interally balanced, you would buy a neutral-balance flywheel and you need not do anything to the flywheel. If it is externally balanced, this would generally be accounted for and you would buy an external-balance flywheel and, again, you would do nothing more to the flywheel. In either case, the final balance is done on the crank. The flywheel's balance, either neutral or imbalance, are not altered and is only a component in the crankshaft balance.
Edit: to clarify this, an internal balance means that all of the considerations for the rotating and reciprocating forces are accounted for on the crankshaft. For an external balance, the opposing forces can not be accounted for on the crankshaft alone (technically, most of the time it can but it becomes a rather expensive affair with the many slugs of Mallory metal needed to achieve this). Whatever flywheel you buy, if the engine is interally balanced, you would buy a neutral-balance flywheel and you need not do anything to the flywheel. If it is externally balanced, this would generally be accounted for and you would buy an external-balance flywheel and, again, you would do nothing more to the flywheel. In either case, the final balance is done on the crank. The flywheel's balance, either neutral or imbalance, are not altered and is only a component in the crankshaft balance.
Last edited by gerry72; May 10, 2010 at 07:28 AM.
Thread Starter
Pro
Joined: Aug 1999
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From: Perth,Western Australia,Australia
Thanks Gerry72, the reason I ask is because i am converting from an automatic to a 5 speed manual hence the need for a flywheel, so i will presume that my 350 is internally balanced and look for a neutral-balance flywheel right?
Race Director
Joined: Jun 2000
Posts: 10,037
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From: FL
1986 and later Gen I SBC. Neutral on the harmonic balancer, external weight on flywheel. This is due to having to change the flywheel end of the crank to fit the one piece rear main seal. The later flywheel also has a smaller bolt pattern than the older one so don't worry about parts interchanging.
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
That is right- I still haven't been able to wrap my coconut around them changing things that have worked since 1955. The one piece seal engines do use external balance.
Race Director
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From: FL
Last edited by SteveG75; May 10, 2010 at 03:37 PM.
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Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
One other thing is some crappy machine shop will balance an externally balanced motor by drilling holes in the flywheel. Don't let them do that
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
If you're adding any HP, get a flywheel with an SFI spec which will take more punishment. Something like this:
http://www.summitracing.com/parts/RAM-1501/
$214 is cheap insurance.
FWIW
http://www.summitracing.com/parts/RAM-1501/
$214 is cheap insurance.
FWIW
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
the '86-up 1 pc rms sbc have (what I consider) a "hybrid" balance.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Perhaps you don't need billet. Perhaps your 350 will work fine with an OE-grade piece.
if so ... consider lite (~16 lb) L88 flywheel ... it is small & has 153 teeth. It fits any neutral balance sbc or BBC including 2 pc rms 350. They are cast steel. In USA, Perfection-Zoom p/n 50-6516 typically retails for under $90 USD at chain parts stores.
Look up flywheel for 1969 Corvette w/ L88 427 BBC
Advance has it for $70
http://shop.advanceautoparts.com/web..._1251454294___
if so ... consider lite (~16 lb) L88 flywheel ... it is small & has 153 teeth. It fits any neutral balance sbc or BBC including 2 pc rms 350. They are cast steel. In USA, Perfection-Zoom p/n 50-6516 typically retails for under $90 USD at chain parts stores.
Look up flywheel for 1969 Corvette w/ L88 427 BBC
Advance has it for $70
http://shop.advanceautoparts.com/web..._1251454294___
Thread Starter
Pro
Joined: Aug 1999
Posts: 749
Likes: 0
From: Perth,Western Australia,Australia
Perhaps you don't need billet. Perhaps your 350 will work fine with an OE-grade piece.
if so ... consider lite (~16 lb) L88 flywheel ... it is small & has 153 teeth. It fits any neutral balance sbc or BBC including 2 pc rms 350. They are cast steel. In USA, Perfection-Zoom p/n 50-6516 typically retails for under $90 USD at chain parts stores.
Look up flywheel for 1969 Corvette w/ L88 427 BBC
Advance has it for $70
http://shop.advanceautoparts.com/web..._1251454294___
if so ... consider lite (~16 lb) L88 flywheel ... it is small & has 153 teeth. It fits any neutral balance sbc or BBC including 2 pc rms 350. They are cast steel. In USA, Perfection-Zoom p/n 50-6516 typically retails for under $90 USD at chain parts stores.
Look up flywheel for 1969 Corvette w/ L88 427 BBC
Advance has it for $70
http://shop.advanceautoparts.com/web..._1251454294___
