1978 gmc k15 starter issue.

[Boothby1952]

Just picked up a1978 gmc k15 with 350ci. I couldn’t find any engine block numbers to reference for right parts, so I “assumed” it was the original engine. I bought a new starter and after install, I pulled out the bendix to take the measurement and found the bendix hit the flywheel, not even coming close to them engaging. I had to drop the starter approximately 1/2” for the teeth to engage. 1/2” seems a bit much and now wondering if there had been an engine swap.
Any info, suggestions and/or new cuss words would be greatly appreciated.

 

[Dutch Rutter]

If you can, count the teeth on the flywheel. It could either have a 168 tooth or a 153 tooth. The starter should be for that same tooth count as your flywheel.

Most trucks SHOULD have the 168 tooth but over the years things get replaced and swapped all over the place. Best way to know is to count it out.

Also make sure to shim your new starter. 1/2" does seem like quite the ways to shim, I'd expect that is the smaller flywheel.

 

[Boothby1952]

Thanks, Dutch. Determining flywheel size would be a good place to start. It would answer some questions too. I did read that starter bolt pattern can determine flywheel size. My starters, both old and new have diagonal bolt pattern, which indicates 168. Is this true?