Small Block Chevy Bellhousings

[Hammer]

Hoping for help from the Brotherhood for a friend.

He has swapping a post-86 motor (300HP GM Crate Motor) into a 1973 Nova that had a pre 86 motor. The flywheel on the pre-86 motor is the 153 tooth and will not fit on the post-86 crankshaft. Will the bellhousing off the pre-85 motor fit the new larger 168 tooth flywheel and 11" clutch, or does he need a different bellhousing?

Motor is on a stand and the tranny under the car so at this time it is a little difficult to just bolt them up.

Any help is appreciated.

[XfireZ51]

I don't thonlnthe bellhousingnhas any relation to the number of teeth on the FW. They're all small blocks.

[flyin ryan]

Um...not sure about the 153 tooth pre/post deal John. Not that it really matter's as it relates to your post, but if the flywheel doesn't fit I'm thinking it's because of the later style being a one peice rear main seal. About your question, not 100% sure but thinking he may need to change to a 10¼" clutch & maybe even smaller bellhousing. I'm not an expert on production style clutch/bellhousing combo's but what your mentioning is ringing a bell to some degree.... Wish I could be more sure for you. Bellhousing should fit for sure unless it's an early 283 one...then I can't say 100%, very early ones may, may be smaller, (50's to early 60's).

[Hammer]

Thanks for the replies.

XFire: the bellhousing will bolt up but as noted below my friend doesn't think the larger flywheel will fit inside the bellhousing when everything is bolted up.

Ryan: That's exactly why the flywheel doesn't fit. Chevy changed the design of the flywheel bolt pattern and the mounting flange so you couldn't put the wrong flywheel on. Pre-86's were internally balanced motors so the balancer and flywheel were neutral balanced. One of the problems with the different flywheel diameters is the mounting of the starter, which we haven't tried because we have no flywheel.

My friend is saying it appears the flexplate won't fit inside the bellhousing and that's where the questions come in.

Another question, will an LS1 truck bellhousing bolt up to the Gen I SBC and will it take care of the potential problem of the 168 tooth (14") flywheel fitting inside it and will the clutch mechanism work?

Again hoping someone might have some real world experience with this type of swap.

[Bob G]

As I recall all chevy bellhousings will accept both 153& 168 tooth flywheels

[XfireZ51]

I see. As for the LS bellhousing, there are several threads on both Digital Corvettes and ThirdGen. org for LS swaps into C4s and 3 Gen F bodies.
=Jeff= and I had been looking into the LS swap into my old 84. We found that the BH would be an issue because of the LS flywheel. It was. reason why the swap would make using a ZF trans difficult. I had heard that Bill Boudreau may have a solution for that. LS swaps have been done using an auto trans.

Originally Posted by Hammer

Thanks for the replies.

XFire: the bellhousing will bolt up but as noted below my friend doesn't think the larger flywheel will fit inside the bellhousing when everything is bolted up.

Ryan: That's exactly why the flywheel doesn't fit. Chevy changed the design of the flywheel bolt pattern and the mounting flange so you couldn't put the wrong flywheel on. Pre-86's were internally balanced motors so the balancer and flywheel were neutral balanced. One of the problems with the different flywheel diameters is the mounting of the starter, which we haven't tried because we have no flywheel.

My friend is saying it appears the flexplate won't fit inside the bellhousing and that's where the questions come in.

Another question, will an LS1 truck bellhousing bolt up to the Gen I SBC and will it take care of the potential problem of the 168 tooth (14") flywheel fitting inside it and will the clutch mechanism work?

Again hoping someone might have some real world experience with this type of swap.

[flyin ryan]

Originally Posted by Hammer

Thanks for the replies.

XFire: the bellhousing will bolt up but as noted below my friend doesn't think the larger flywheel will fit inside the bellhousing when everything is bolted up.



My friend is saying it appears the flexplate won't fit inside the bellhousing and that's where the questions come in.

Yup, I'm with you 100%, John. I know the Bellhousing will bolt up to the block, but the early, early one's may start to angle down at a steeper rake hence 168 tooth flywheel may not fit...again, I'm not 100% sure, not my game I do everyday. I do run a 153 tooth flexplate on my Stingray but I can help you any from that. My Comp. Elim. customer runs an even smaller 141 or 142 tooth flexplate, pain getting the starter close enough to engage & turn that thing over...

[Hammer]

After quite a bit of research, we have found that a larger bellhousing must be purchased for the 168 tooth flywheel. Looks like what is know as a "621" bellhousing is what's needed. It appears that a bellhousing from an '85 Chevy truck with a manual transmission will work also.

Thanks for the replies guys.