[31ROC]

Originally Posted by 31ROC

OK guys,,,,here's what I got...removed 700R4 today, attached are pics of crankshaft and flexplate....this should help you all determining what to buy for a clutch and flywheel.....I believe it is 1 piece seal so that should help!

Well now I'm even more confused...(this is easily done)....I was fairly sure I had a 1-piece seal motor from the info I absorbed from another thread giving the block number I found. Now (see attached pics), after reading more on-line info (GMparts-direct), if I have a 3.58" bolt circle for the crank flange, then it is a 2-piece seal motor, which is pre-1986? So I measured the flex plate after removing, measured the 6 bolt mounting holes, and sure enough it is 3 1/2". So does this mean I have a 2 piece seal, pre '86 motor? and need a flywheel without counter weights?
Do I match the diameter of the flex-plate to the new flywheel and same amount of teeth-correct? (153)

[1971BB427]

Yes, you match the same number of teeth on your flexplate to the new flywheel. Should be about 25 teeth between holes on a 6 hole flexplate for a 153 tooth.

[ssmonty]

I didn't read the whole thread, but I will tell you that the engine in post #28 does not have a one piece seal block/crank. It's a two piece RMS.
ssmonty

[31ROC]

Originally Posted by ssmonty

I didn't read the whole thread, but I will tell you that the engine in post #28 does not have a one piece seal block/crank. It's a two piece RMS.
ssmonty

Thanks SS....this means internally balanced crank right?
So correct flywheel should be for 2-piece main seal engine, not have counter weights on it, and have the larger 3 1/2" mounting bolt circle?
Are these flywheels (153 tooth), all the same diameter?
I believe the flexplate I removed was about 12 3/4" in diameter....so the new flywheel should be the same?

[ssmonty]

1.Thanks SS....this means internally balanced crank right?
2.So correct flywheel should be for 2-piece main seal engine, not have counter weights on it, and have the larger 3 1/2" mounting bolt circle?
3.Are these flywheels (153 tooth), all the same diameter?
4.I believe the flexplate I removed was about 12 3/4" in diameter....so the new flywheel should be the same?

1. Just by looking at the crank flange, as long as its not a 400 crank, YES.
2. YES. The 400 crank would have a weight on the flywheel, as well as any one piece RMS crank.
3. As far as I know yes. You can use the same starter in the same bolt holes on the block.
4. As far as I know yes. You can use the same starter in the same bolt holes on the block.

[496CHEVY3100]

only the sb400 had a weight attached to flex plate /flywheel also had a larger harmonic balancer look on back side of balancer If it has metal removed approx 1 " wide 5 " long it is a 400 external balance requiring matched flywheel ,if not you can use pre 85 2flywheel with larger bolt circle offered in 2 tooth count with maching starter ,if i remember correct 168 has staggered mounting holes 153 are straight across some have 2 long bolt some 1 long 1short,. I know before someone replies 454 also had added weights external balance

[31ROC]

Originally Posted by 496CHEVY3100

only the sb400 had a weight attached to flex plate /flywheel also had a larger harmonic balancer look on back side of balancer If it has metal removed approx 1 " wide 5 " long it is a 400 external balance requiring matched flywheel ,if not you can use pre 85 2flywheel with larger bolt circle offered in 2 tooth count with maching starter ,if i remember correct 168 has staggered mounting holes 153 are straight across some have 2 long bolt some 1 long 1short,. I know before someone replies 454 also had added weights external balance

Thanks, the flexplate I removed had no weights....so going with a Pre-'86 350 small block....the flexplate had 3 1/2" mounting bolt circle.

[1971BB427]

So have you counted the teeth on the flexplate you removed to determine if it's 153 or 168?

[31ROC]

Originally Posted by 1971BB427

So have you counted the teeth on the flexplate you removed to determine if it's 153 or 168?

Yes sir....the flexplate had 153 teeth...

[V8&4spd]

You have a 2 piece seal engine. The crank flange on a 1 piece seal engine is round. The small flywheel for a 2 piece seal engine is easy to find, they are the most common. SBC used a big flywheel until the early sixties and then the small flywheel became more common. Trucks used the bigger flywheel and most of the cars used the smaller flywheel.

[31ROC]

hmmmm..... this block illedgely (sp?) came from a truck.....

[V8&4spd]

It does not matter if the block came from a car or truck. You can use either the big flywheel or small flywheel for a 2 piece seal engine as long as you have the right flywheels. The only difference will be the starter mounts on the block.

[31ROC]

Originally Posted by V8&4spd

It does not matter if the block came from a car or truck. You can use either the big flywheel or small flywheel for a 2 piece seal engine as long as you have the right flywheels. The only difference will be the starter mounts on the block.

Well...i dont wanna change my current starter which is mounted on the block.....so which flywheel should I be buying if flexplate which was removed was 153 tooth?

[V8&4spd]

Both the big flywheel and small flywheel starters are mounted on the block, they just use different mounting holes. If you have a mini starter it might be drilled for both flywheels. The small flywheel or big flywheel use is up to you. The small flywheel aluminum bell housings are easier to find and they usally want more money for the big flywheel bellhousings. If you go to a scatter shield and big flywheel you are adding weight to the car verses the small flywheel and aluminum bellhousing.

[31ROC]

I am planning on a scattershield bell just to be on the safe side.....and dont care about weight at all.....dont I buy a flywheel which is same diameter as the flexplate which came off? (12 3/4")