I am putting a smallblock engine and 998 torqueflite together, and went to mount the starter. The upper hole in the starter is .620 diameter ( too small to accept a 5/8),the bolt hole in the trans case is 7/16 threaded bolt hole. The lower hole in the starter is 7 /16 and matches what is in the trans case.
What am i missing hear? I am not sure where this starter came from, it is a new style small starter.
Do i have the wrong starter? Do i need a special stud?

sounds like the hole in the starter (.620) is sized for a metric bolt 12mm maybe, thats even too small for a 5/8 bolt

are you sure on the bolt size? both the upper and lower bolt/stud on mine are 7/16 dia. with a 5/8 head/nut.

now that you mention it you are right, it should be a 7/16 bolt/stud not 5/8 I stand corrected.also their is normally a stud with 7/16 coarse that screws into the bell and the other end is 7/16 fine thread for a nut and washer

I never gave it much thought before. Is it oversized to allow a little room for things being off a bit? .180 oversized is a bunch though. I went to an auto parts store and the picture looks like what i have?

I have an old Nippondenso laying here and the upper hole is about 5/8. The snout of the starter in the bore in the trans is what locates and supports the starter.

Thanks. Looks like i am just overthinking it.

Between three cars big blocks and small blocks, powerglides and Matt’s 727 almost all of my starters are modified. One setup I had to open up the one bolt hole for the stud on my adapter plate. Several I have to cut the nose off all together. Whatever it takes to work

I ran into the same thing last fall on my starter. As stated above the nose locates the starter and the bolt/stud just hold it in place. I couldn't see that much being correct so I made bushings to fit 7/16.

Greg I have never had a problem using 7/16 bolts and letting the mini starter center on the recess in the bell housing with my smallblock/904 stuff

Same here with my BB/727. 6 years 500+ passes.
Doug

Thanks again, guys. Time to get this 408 504 hp motor into my flywieght 65 Dart😀

on the nip nipondenso starter just move the stud to the upper hole on the trans you will be fine. mother mopar reversed the holes on later model vehicles

Done!