bellhousing interchange ?

[black dawg]

Working on a mid 70s k20 that one starter bolt hole is beyond repair. Truck is a manual, and curious if I could use one of the older bells that the starter bolts to get a starter working on the thing again. Not sure if those older bells interchange or even what years they were used.

 

[diesel4me]

I'm not sure what years you can use an old cast iron bell-housing on,I think 1972 was the last year GM used the ones that also had cast in mounting pads,a carry over from the late 50's when the engines were mounted with angle brackets attached to the block next to the timing cover ,and used those two bell housing pads as rear mounts for support for both the engine and transmission...(most trucks back in the 50's had no transmission cross member )..

My '72 K5 I had,came with a Th350 that refused to go in forward gears until it was "warmed up" and left in drive or first for several minutes--I eventually tired of this and almost got fired thanks to it making me late for work often,so I decided to buy and swap in a SM465 setup..the bell housing I got from another '72 was the cast iron one,that had the starter nose that bolted to the bell housing,instead of the block,so I had to buy the starter also..

Since my K5 originally had an automatic,the starter used to bolt to the block..I had no issues installing that cast iron bell housing,or the starter,and it worked fine--I see no reason why it wouldn't also work on any '73-87 truck..the only thing that may pose a problem is I think some later years of SM465's had a larger input bearing housing,and are too large to fit in the cast iron bell housing,but I'm not 100% certain of that,its just what I've read online..you could probably have it hogged out to fit if its too small..

 

[Truckman4life]

I think my cast iron bellhousing sm465 has the clutch pivot on the engine and an aluminum one I also have has the pivot on the bellhousing.

 

[diesel4me]

Hmm,never recall seeing the clutch linkage ball going in the bell housing,--on my '72 I had to put the ball stud thing for the clutch linkage in the threaded engine block hole..

I haven't seen too many '73 up manual transmission setups in 4x4s,only one I had was a '75 K5 2wd with a straight six ,three speed Tremec tranny,and I'm pretty sure the ball stud was on the engine--I swapped a 307 V8 into it and cant recall any ball stud being in the bell housing..but it was a long time ago too.

 

[nvrenuf]

Does your engine block not have threaded holes for a starter?

 

[Truckman4life]

I'll double check. It's out of a 76 I believe.

 

[diesel4me]

Most if not all GM V8's have at least two holes drilled and tapped in the block for the starter,sometime in the 60's,--some earlier ones had 3 holes in the block...early models used the cast iron bell housing and the starter that bolts to it instead...
The first post stated "one starter bolt hole is beyond repair",so I assume he is looking to go with the starter that bolts to a bell housing instead of the block..

 

[Truckman4life]

@diesel4me 76 3/4 ton with a smallblock.

 

[diesel4me]

Interesting...like I said,I have not seen too many manual transmissions in GM square bodies around here--I'd guess 95% of all sold in this area were automatics..does your engine still have a spot for the ball stud ?

My '75 K5 2wd may well have had that type of bell housing--I cant remember if the ball stud was on it,or the engine block..

I do recall it was a "closed" bell housing,that had to be removed to get at the clutch--my cast iron one I put in the '72 had a tin shield you could remove and drop the clutch out thru the bottom,which I liked better..(and was probably much stronger than the aluminum one)..
It also had the 3 bolt "face mount" for the starter nose,that was more like a Ford style than the typical 2 bolt to the block style used on most other GM's..

 

[black dawg]

so the hole that was messed up (block broke out then repaired, then another broken bolt that somebody tried to weld to, and welded it to the block) was the forward bolt of the diagonal starter pattern. Extracted a broken bolt from the outside bolt hole, and using the straight across starter pattern, bolted an afterket starter that fit the bigger flywheel.,,and the straight across starter pad.

 

[diesel4me]

Whatever works huh ?...
I always thought the "straight across" bolt pattern starters only worked with the smaller 153 tooth flywheel,but I guess the aftermarket multi-fit ones work on either size flywheel ?..

Years ago I recall a customer at the parts store that had the same issue--the corner of his block was broken off when the front drive shaft smacked the starter and knocked it right off the engine after a hard landing when he was wheeling..
We opened up several boxes of rebuilt starters and found one that only fit a couple of years with a cast iron nose,that had 3 bolts to hold it to the block instead of two,and that one did bolt up to the inner hole nearest the transmission and the forward hole closest to the motor mount and worked with his flywheel,which I do not recall what diameter it was,probably the smaller 153 tooth one..