Starter Bolts

[Schurkey]

The inline (Old, heavy style) starters use 3/8 bolts having a knurl on the threaded end, to tighten-up the clearance in the starter and block bolt holes.

The Permanent-Magnet Gear Reduction (PMGR) starters have METRIC bolt holes, 10mm--slightly larger than the 3/8 holes in the block. Actually, they're cast holes, not drilled--so the measurement is approximate. As-cast holes don't require extra machining, so it's a cost-saving measure.

PMGR starters need 10mm shank bolts, tapered down to 3/8 threads.

Using "old style" 3/8 bolts screwed-into 10mm bolt holes makes for a sloppy fit, prevents proper starter alignment, and does nobody and nothing any good.

If you've got a "mini starter" with 10mm bolt holes, you'd better have bolts with 10mm shanks, but they still have to thread into the SAE threads in the block. Thus the step-shank bolts made by ARP and GM; as pictured in my post above.

 

[someotherguy]

There's some unnecessary confusion here. The LARGE (full-size) direct drive starters use longer bolts. They're obviously longer. If you used those bolts on a mini-starter, they would not thread all the way in. Some people attempt to use stacks of washers, nuts, etc. to space the bolts instead of using the proper bolts. I don't get why this is confusing, but whatever.

Richard

 

[BloodMoneyOBS]

Richard,
That's what I mean--the starter I installed was a magnetic reduction starter that was slightly smaller and lighter in weight. The factory bolts seemed to fit fine. Are you guys saying that the smaller reduction starter should have different bolts?
I did not know there were two different styles of starter bolts for the small block V8's on the GMT400's? Vorteec vs TBI ?

The TBIs generally had direct drive starters from the factory, as I understand it. The gear reduction starters started coming in for 94, and I'm pretty sure they were standard in 95.

 

[alpinecrick]

The TBIs generally had direct drive starters from the factory, as I understand it. The gear reduction starters started coming in for 94, and I'm pretty sure they were standard in 95.

Blood,
My 96 and 97 K1500's have/had conventional starters. My 97 still has the original starter. Been expecting the starter or solenoid to go out any time now. When it does I'll put a mag reduction starter in it.