SBC starter issues

Hey guys, I own a 1986 k10 with a 70's 350 installed with a 700r4. I replaced the flexplate and starter(3 times) but cannot seem to get it right. when i installed the started with no shims it works great about 5 times then it starts to grind and then not catch at all. I have tried shimming it with 1 shims, then 2 shims, and even 3 shims but no luck! 1 shim does the same but only work about 2 times and the same for 2 and 3. any help with be awesome. thanks guys! bothe the felplate and starter are for a 1979 chevy which goes with my block.

Well what is happening, too deep an engagement into the flywheel or not deep enough, what do the parts look like, have you manually egaged the starter drive to see how it contacts the flywheel? No way to tell from here what the root problem is.

Sounds like the problem wont be fixed with shims. It's the starter itself. Probably a tired,worn out bendix drive and solenoid or a worn out bushing in the nose cone. That is if your cables and voltages are good.

well it looks as if the starter is only contacting half the width of the teeth like its not engaging deep enough. The voltage is all good. All new wires and battery as well. there is a spacer installed on the shaft that prevents the teeth on the starter from going out farther. was wondering what would happen if i cut that off? probably a deeper throw?

Not the answer, sounds like that starter is wrong.

I am not sure but symptoms showing that it would be the starter issue. you just cut it off and see what will happen or bring it to a good garage to identify the issue and you will save your time and money.

It sounds to me like you have the incorrect starter bolts, do they have the nurling on them or the bolts are not tight enough . or are just stretching and allowing the starter to mover on the engine block. That mat be why the starter works for a few starts then starts to cause issue.

well it looks as if the starter is only contacting half the width of the teeth like its not engaging deep enough. The voltage is all good. All new wires and battery as well. there is a spacer installed on the shaft that prevents the teeth on the starter from going out farther. was wondering what would happen if i cut that off? probably a deeper throw?

The bendix gear might get stuck in the flexplate and keep running. Disconnect the strap from the motor to the solenoid and then apply good batt voltage to the solenoid and see how deep it engages in the ring gear without having the engine cranking.