Starter bolt size...Powerglide to BB

[Dano65]

I'm working on a friends 73 Challenger 540" BB and we just installed a powerglide in it but while installing the starter the 3/8's bolts seem to fit pretty sloppy and I'm afraid to tighten them up and risk stripping the threads in the bellhousing. Could these be metric? I wouldn't think so but nothing would surprise me. Anyone have experience with this? TIA

 

[omegamonk]

I’d try a 10mm bolt and see how it threads in

 

[khryslerkid]

Maybe they're 7/16" ?

 

[Dano65]

10mm only threads in a bit before binding so that's not it and 7/16 is too big. I messaged them on FB to see what they say. I have the bolts that came with the starter shim kit and they fit sloppy too? I told them if I tighten them up very much they will pull threads. Guess I'll wait and see what they say. It's a J.W. Transmission Ultra-Bell bellhousing. Thanks for the replies.

 

[beanhead]

If the 10 gets a few threads and then gets tight, the threads may just have some gunk in there...clean them out real good and try it again if you haven't already. Although at this point I would probably just tap it..

 

[Dano65]

If the 10 gets a few threads and then gets tight, the threads may just have some gunk in there...clean them out real good and try it again if you haven't already. Although at this point I would probably just tap it..

That's what I'm thinking now. They did supply bolts with the bellhousing/starter shim kit and they are indeed 3/8" bolts. I just do not like how sloppy they fit and I refuse to tighten them down cause I know it will be trouble if I do. I don't know why they're like this?

 

[33 IMP]

If I were to guess why they are like that, I would say that the drill they used for the hole, prior to tapping, was oversize or dull. I would consider helicoils. I saved a high-dollar torque converter that way.

 

[Garys1969RR]

I have a powerglide behind my big block, Came that way on purchase. Mine has studs threaded into the trans or adapter plate for the starter mount. We just took it apart a couple months ago. I would put 7/16studs in there, makes it way easier to mount the starter. I'm sure mine are bigger than 3/8, prob 7/16. I'll check next Friday when we go work on it, and post a few pics.

 

[Dano65]

Didn't even think of studs! That's a great idea and will be easier to do since it's out of the car.

 

[Dano65]

You were right, just checked and they're 7/16" lol no wonder the 3/8" were sloppy. Looks like the upper bell bolts are 3/8" and lower and starter are 7/16" Thanks for the help! Going to pick up studs now. I was thinking about studs for all the bolts? Would make it easier to line up the trans since I'm just using a floor jack. Good/Bad idea?

Thought I checked 7/16" earlier but they were 1/2" that's why I thought they were too big. Been working on cars for 40 years now and you'd think I'd know bolt sizes by sight now.

 

[Garys1969RR]

Not a bad idea to use studs where the trans and motor have to line up with each other. At least in a couple of places where you can get to them. Glad to be of help!