4.3 stroke balance

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4.3 stroke balance

Post  mach1charlie on February 19th 2017, 8:08 pm

So I am looking at a rotating assembly, seller says he balances internally with H-beam rods 6.8, wiseco pistons. Scat cast crank. This is a low buck deal, I don't expect Mallory metal to balance. So is the Bob weight that close on a cast crank?

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Re: 4.3 stroke balance

Post  Gregaust on February 20th 2017, 4:46 am

In my 4.3 crank it took 2 mallory slugs to internal balance, using H-Beam rods and JE pistons . I've done a couple 4.15 cranks have taken no mallory

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Re: 4.3 stroke balance

Post  Scott Foxwell on February 20th 2017, 9:18 am

Depends on the counterweight. The longer the stroke, the smaller the counterweight has to be for piston clearance @ BDC. If the counterweight was cut for a short rod then you might need some mallory. If it was cut for a longer rod then maybe not.

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Re: 4.3 stroke balance

Post  rmcomprandy on February 20th 2017, 12:48 pm

The lowest I have ever seen a bob weight with normal non high dollar racing components with a 4.3 stroke assembly is about 2,230 grams but, around 2,340 grams is more realistic.

With that bob weight and some creative counterweight machining you can usually get the front to be "0" balance but, the rear will still use a 24.2 external balance O.E.M. flywheel/flexplate, (similar to a 428 FE), when using a CAST 4.300" stroke crankshaft.  Mallory slugs have always been needed to get it to balance totally internal with around that bob weight..

A forged 4.300" stroke crankshaft has heavier counterweights and can usually be balanced internally without Mallory.

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