V8 Conversion Flywheel

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I have heard that if using a swapping in a 350 from 85 or older that you have to use a different flywheel than if you are using a 86 or newer 350 due to the fact that the engine is internally or externally balenced. is this true?? Thanks
 
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Manual trannies require a heavy flywheel (steel) to hold the clutch and to transfer torque from the crankshaft to the trans input shaft. Auto trannies accomplish it with a torque converter (hydraulic) so don't need the mass.

So the manual is externally balanced? Not sure.

Also, with an auto is the harmonic balancer bigger to compensate for the lack of a massive flywheel? Or is there some internal component? Heavier crank? I thought a sbc was a sbc on the inside?? ???
 
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You are correct, but IIRC the reason is that GM changed the rear oil seal on the sbc in 1985. This resulted in a change in the size and bolt pattern on the rear of the crank.
 

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[quote author=Medusa link=board=1;threadid=5451;start=msg43082#msg43082 date=1064008251]
You are correct, but IIRC the reason is that GM changed the rear oil seal on the sbc in 1985. This resulted in a change in the size and bolt pattern on the rear of the crank.
[/quote]

BINGO!!

http://www.northernautoparts.com has flysheels for like $120 each.

I was NOT happy when everything for my 91 motor install was set and ready, only to discover the 78 flywheel wasn't gonna work.
 
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hey jhaha just wanted to add my 2 cents worth, yes the 85 and older sbc use 168 tooth flywheel, 86 and newer use different bolt pattern because of rear seal, if you are useing 80 to 85 chevy block make sure you use a metric starter. i found out the hard way. if your dip stick is on the drivers side its 80 or newer and the starter bolts are 14mm, i went through 2 starer nose cones before i found out, i was wondering why my 9/16 wrench was a little lose on the bolts (da) and it sounded funny when i started it.
 

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