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all BBc engines are external balancer ??

R72K5

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ok i was talking to a local mechanic yesterday out here and we got into a few different interesting subjects

one of them was about internal vs. external balance

he says that all the chevy big blocks were external balance

i was always under the impression that only the 454's were externally balanced-

and that all the rest of the BBC engines were internal balance(IE use harmonic dampners- instead of crankshaft balancers)


what is the true story ?

this discussion between him and i began after he told me how and where he found his pontiac 400 he has in his 86 grand prix he built and drives now,

he got it for free, found it literally in a scrap iron place, laying on the ground,..

old 4 bolt one even.
 
396 and 427 i believe are internal, and all the others could go both ways i believe, but that just may be if its a OEM or custom motor build.

ive been shopping for a 454 and been seeing those listed as internal or external.

FYI, Fluidamper offers internal BB dampers.
 
454 is the only one that is externally balanced, the flex plate is specific to the 454. 396,402,and 427 use the same flex plate as a small block.
 
454 is the only one that is externally balanced, the flex plate is specific to the 454. 396,402,and 427 use the same flex plate as a small block.
Yup, what he said. BUT don't go thinkin you can use a 400 SB EXTERNAL flexplate on a 454! It's different, even though it bolts on. I had a customer do that!! Took me a bit to figure that out!! :( :(
 
so i was right all along and the mechanic is wrong ? only the 454 BBc's are external balance and the rest of the BBC's are internal

right ?

thanks
 
R72K5 said:
so i was right all along and the mechanic is wrong ? only the 454 BBc's are external balance and the rest of the BBC's are internal

right ?

thanks
yup! 366 stuff, i am not sure though. i think they share some 454 parts? :dunno:
 
As stated the 454 is the only externally balanced bbc, the 366 is still internally balanced.
 
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