Chevrolet Repair: 454 eats starters, shims, chev

Question
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Followup To
Question -
Hi,
I have a '79 chev dually, w/ gas 454. Starters only last from one day to six months.
Answer -
Block warping is a possibility especially on the older 454's, are you sure the starter is being shimmed correctly ? it is very improtant that the shimms are reused that came with the original starter

Response;
There were no shims when I got the truck. The teeth only overlap 50% unless the starter housing is machined down. Even then it only lasted 6 months. The mechanic ground two housings down too far before modifying one that meshed fully.

Answer
Have you checked all the teeth on the flywheel ? is it is good condition, this can also ruin a starter if the teeth are badly worn or broken in a few spots, I am assuming you probably have already checked this but in case you didnt, wish I could help more but sometimes nothing can replace actually looking at the problem