I just bought an aluminum bellhousing. The hole on the bellhousing is 5 1/4 inches, I've heard that muncies are 4 5/8 inches. Is this going to be a problem (alignment)? Thanks for your time, any help would be greatly appreciated. -Adam

The "bore" on a GM C3 smallblock bellhousing is 4-5/8.

If you have an aftermarket piece designed for the Muncie, then the four mount holes should line up. If they don't, then you are SOL anyway. The extra room around the center won't make any difference to the trans bolting up.

BUT, that larger centerbore MAY cause another problem: an incorrectly positioned clutch-fork ball-stud. This can affect the proper positioning of the fork on the throw-out bearing. The possible difference is 5/16" - which ain't much if you're building a house. But it's a country mile in machinery terms.

Some part numbers or source info on the bellhousing could tell us something more. Based on what you've presented, this is the best I can tell ya'.

John

In addition, if the hole is too large in the housing, the trans may not line up quite right with the crankshaft. There is a slight play to the bolt holes, so center is not exact. While this may not seem like a big deal, it can acellerate wear on the pilot bearing, clutch, and trans input shaft and bearing.