Have a 1972 350 from a c-10.
I started having starter trouble after a replacement 6-7 months ago. The last starter ate up my ring gear, so I replaced both three weeks ago. Now I'm starting to have to same problems as before. When I bump the key I hear a high pitch whinning sound, like the starter gear hits the flywheel teeth or just not ingaging all the way. Sometimes the starter turns the flywheel and it starts. It sounds terrible! I thought the flywheel may need shims so I fitted them from thick to thin. I once had all of them in. I just can't get it to turn correctly. I'm wondering if anyone has had this problem before?

Had the same problem when replacing starter.
Starter needs to be shimmed to give specific clearance between starter and Ring gear. Can,t remember measurement but I know that a paperclip will give you the correct gap between teeth/gears.
The starter will make the most damaging sounding noise if not set up correctly, and will destroy the meshing teeth.
Shims may need to be used across both mounting bolts or just one depending on clearance required,one side shimmed will increase clearance and other bolt will decrease clearance purely a case of trial and error to get it right but providing the paperclip clearance is met you will have a sweet sounding starter.Check clearance in three different places on flywheel.
Hope this helps, I guess that the starter is matched to amount of teeth on flywheel as there are two types as far as I can recall

Some starters REQUIRE that the bracing be used to maintain proper alignment. If your truck originally had a brace that held the starter at the backside and it's been removed, the starter will not mesh correctly with the ring gear no matter how many shims have been used.

The paper clip trick has always been useful for me eliminating starter noise.

Vince

Shims move the starter drive gear away from the ring gear. Sounds like you may already be too far away!!!. I recently had nearly the same problem Did not grind on it enough to eat up the ring gear teeth) and the starter drive gear was .050 " too far from the flexplate. This starter was from Tiawan and the QC is non existant!!! Also agree you need the nose brace to keep the starter from moving away from the ring gear.

Trees

Not trying to be wise, but you do have the right ring gear (flywheel) for the starter or vice versa? By this I mean 153 tooth is 12-3/4 " and 168 tooth is 14 ". An offset starter (mounting bolts) require a 168 tooth, and usually straight across mounting bolts use the 153 tooth flywheel.

If i can remember that some chevy starters did not need shims but needed to have some shaved off the back because the starter was to close to the flywheel.----I hope this is helpful...

Aftermarket starters often have poor quality nosecones . Try a delco starter when you find one that works keep nosecone to put on next starter. Alos brace is important

I had a lot of problems with autozone and the like starters. They are JUNK, dont waste your time or money. If you are really on a budget, go to the junkyard and pick one up. Have them test it there. Thats what I did, cost me 10 bucks and i have had no problems since.

Whatever you grind off, can be shimmed back later. I find an angle grinder has enough precision

Doc here,

Well, After THREE YEARS...I wonder if he EVER got it fixed...I'll just bet he did,
..maybe he'll post back and tell us...

Auto Zombie starters are CRAP as far as QC..The mindset is kick 'em out the door as quick as possible..damn if they work..

A Resolution to the quagmire is, A Genuine AC Delco start from a "Mom and Pop" OR if you don't have access to someplace like that or a steal..uh...Dealer.. Than Get a Mini Starter...

OR (AND..) NEVER Core the stock starter..they are too easy and too Cheap to rebuild..and end up with a 150% BETTER unit than you could possibly but today..ANYWHERE..






Doc

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Yeah I've been having most of the same problems, except my truck will make the same high pitched squealing noise when i try to crank it the first couple of times and then it will just stop even trying to crank. So I've just been hooking my jumper cables up to it and letting it sit for a couple of minutes and then it will start right up while making the same awful noise. I replaced the starter, battery, voltage regulator, and alternator about 7 months ago and just had them all checked today at the auto zone, where i bought all of the parts, and the guy said that they checked out fine. Could someone please help?

Did you read all the above post?

Yeah I read them all...but it turned out to be the post on the starter that the battery cable is hooked up to was very loose. I tightened it and it started right up. The only problem now is it is still making a high pitched whine once the solenoid dissengages.

Flywheel on backwards?

The starter teeth may not be fully engaging the flywheel if its on backwards. One good kickback against the starter damages the teeth.

The back of the crank will have a convex radius around the pilot. The flywheel with have what looks like casting flash or stamping flash on its center hole. They must line up so the "flashing" goes toward the front of the engine.

If you find the starter to be too far way from the flywheel forward to backward like on te same plane as front to rear bumper than you have no other choice to to disassemble and flip it around or replace it if it's damaged already.