I have a '68 with an older 327 out of a Vette. Has an 11"clutch, 160+ tooth flywheel, and staggered-bolt cast-nose starter. Switching from "PIA" scattershield (not a race car) to stock bellhousing. Purchased repro 621 housing. It's my understanding that a 621 should have no problem with the bigger flywheel; however, after bolting on the 621, it looks like there is virtually no clearance, if any, between the flywheel teeth and the bellhousing. Is this correct? Should it be this close to the bellhousing? Looks too close for comfort. What are the measurements of an original 621? Any help appreciated.

Anyone know what the inside diameter of an original 621 bellhousing is at the engine?

Anyone know what the inside diameter of an original 621 bellhousing is at the engine?


I have the repro 621 from Classic as well as the large 11" flywheel, no issues here, been running for a while with a TKO behind it. .

I also have the engine apart as well as the 621. What dimensions do you need? If its id, I can get that later this evening .

Yes the ID is what I'm interested in. With the BH bolted on it looks like the FW teeth are almost touching the BH through the inspection hole.

Yes the ID is what I'm interested in. With the BH bolted on it looks like the FW teeth are almost touching the BH through the inspection hole.

Check 6 PM report.

OK,, I agree with Jon on this but if you loose sleep over this, here are my measurments. I see where the closest point would be to your flywheel teeth. It would be the dowel holes which can be shaved a little on this 621 as its got lots of meat here. 13 15/16" is what I got between the dowel holes , ID. Next set of holes would be the lower bolt holes that I measure 14 5/8", there could be some variances on the tapes too.

My Hayes billet flywheel is within thousands of 13.5 id, plus about 9/32" for ring gear height. This may varry too as some of your teeth may be worn. Hope this helps.

It's the same old story, close only counts in horseshoes, darts and nuclear warfare. Don't sweat the close. If the flywheel rubs but still turns, the teeth will wear away the aluminum till it has enough clearance. I've had that happen when doing a turbo 400 swap. There may have been very minor differences in flywheel diameter or bellhousing castings that caused the rubbing in my case, but the problem usually cures itself.

See post #5

I'd be more worried about the darn front bottom "closer" tin hitting and raising one HECK of a loud noise!

I tore mine off that I put on my 406 and it's still in my trunk!

pdq67

Thanks everyone. Looks like the bell housing is going to work. Now to correct my other issue -- clutch fork appears too short.

Thanks everyone. Looks like the bell housing is going to work. Now to correct my other issue -- clutch fork appears too short.

Best to have a factory GM fork and an adjustable pivot ball.