JCM1

Hi guys. I recently got a replica 621 aluminum bellhousing for my Saginaw 3 speed. the center hole for the bellhousing fits fine, it sits flush up against the tranny without any bolts, but the holes appear to be off just a little bit, enough so that when I go to start a bolt I have to pull the bellhousing away from the tranny and then start the bolt. Once it grabs the bellhousing no longer sits straight on the center bearing cover. My instinct is to ream out either the tranny hole, or the bellhousing holes. Is this advisable? Additionally 2 of the tranny "ear" holes are threaded, (on bottom) and all 4 bellhousing holes are threaded. Could I just drill these holes out, getting rid of all the threads and just use nuts and lock washers? I don't see how I'm supposed thread the bolt through both threaded holes on the tranny and the bellhousing As it just pushes rather than catches the threads on the bellhousing. Thanks.

jmd

iTrader: (4)

The bellhousing to engine alignment is based on the two engine block dowels above bolt hole 1 and above bolt hole 7 on Chevy pattern. If the 6/7 bolt pattern bolts are off, that's not a problem if you clear them out a bit.

The threaded lower 2 hole case Saginaw wasn't used with all-4-threaded bell like a 621. Ream the trans. holes out; it's always better to have the option of installing bell separately from trans. than be required to install together.

JCM1

Perfect. Thank you very much. I really appreciate your help.

garys 68

iTrader: (1)

jmd hit it on the head. NEVER ream the retainer bearing cutout on the bell.
I would also recommend zeroing in the bellhousing. The last 621 repro I got was 0.020 off. You should be within 0.005, although the old Muncie, saginaws/T10s are pretty tolerant of runout.
You can get offset dowel pins from Summit.

JCM1

Thank you. You guys are very helpful. Thank you for taking the time to help out a "noob"! I hope to learn enough to be able to help others in the future. Cheers.

JCM1

Update - I bored the transmission bolt holes out just enough to get rid of the threads, and I applied a little grease to the bellhousing hole. I then slowly and gently tightened all 4 nuts down. They started tightening up a bit and then "pop" the whole thing slid together. I checked to make sure nothing cracked, and success! The bellhousing is on there now nice and tight, all even and perfectly seated. I need to look up torque specs next and finish it properly. I then started installing the Hurst shifter but need the bolts to secure the shift arms to the tranny. Thanks again for you help guys!