SBC Changes Question

[flt-blk]

Was there a major change somewhere in the 80's?
One piece main seal
Starter mount
Flywheel size or tooth pattern.


I am looking for a scatter shield for a 93 block and getting confused with
all the options.   By the way if anybody has one laying around please
send me a PM

Can someone break down the differences?

[flt-blk]

I found an adapter steel bellhousing (Not scattershield) from Lakewood PN 77-150 but it only lists

1958-81
Most V-8 and 90 deg. V-6 engines with block mounted starter
Designed for mechanical clutch linkage
GM Muncie/Saginaw, BW T-10
Bore    4.684
Depth   6.374
Fork opening 2.5 X 3.75


I am building a 383 and will probably be using a new Tremec TKO600
Thanks
TZ

[enjenjo]

In 86 there was a major change. They went to a one piece rear main seal, changed the bolt pattern on the flywheel flange, and the oil pan changed to a one piece gasket. The bell housing bolt pattern stayed the same.

The flywheel diameters, and tooth counts stayed the same, but the early and late flywheels won't interchange.

Even with the same trans bolt patterns, there are several bearing retainer diameters, two throwout bearing diameters, three throwout bearing lengths, and at least two input shaft lengths, so that has to be taken into account too.

So the adapter you  found should work, if you can find a flywheel  and starter that are compatible with the clutch plate needed for the trans, and a clutch fork with throw out bearing that will fit the adapter, and the clutch you have.

So the answer is a definite maybe

[flt-blk]

So the clutch pressure plate bolt patterns are all the same

I have a starter off a 78-350, that should work on the 93 block with whatever flywheel it has on it.

Clutch arm must match bell housing
T/O bearing must match Transmission
Transmission shaft length must match Bellhousing length or have pilot
        bushing adapter.

I think I have a handle on this.

[model a vette]

On the later blocks there are two size flywheels, just like on the earlier blocks: 153 teeth and 168 teeth. The old straight across bolt pattern starters will work on the smaller size and the old staggered bolt pattern ones will work on the larger size.

[Dr Flowgood]

also, the one piece seal motors are all externally balanced with a weight on the flexplates or flywheels . sort of like the old 400 small blocks but a different bolt pattern . Unlike the externally balanced 400 motors from the 70's the 86 or 87 (not sure which year they started the one piece seal) the harmonic balancers are neutral balanced.

Doug