Let me start by saying I'm exhausted and likely have done something stupid but for the life of me I can't seem to figure it out. My starter will simply not disengage once the engine fires. I've gone through the electrical and it is correct and the solenoid is not sticking, etc. This has to be a mechanical issue.
302, T5 with correct bellhousing (came with trans), 157 tooth flywheel and yes, block plate too.
Started out with a DB Electrical mini-starter. At first assumed I had an electrical issue due to the PM motor but not the case. Swapped in a stock 1990 standard style, single cable connection unit. Same deal. I've measured the depth of the flywheel from the block plate surface and compared to the seated bendix gear position and those measurements show adequate clearance. Still does it. Found out about a starter shim for Fords (never in my life have I had to use such). Installed one (.100" thick) to move a bit farther back. Still happens.
What the hell am I missing?
Here is a pic of the carnage done to my original mini starter. It looks like the gear sat in just a bit too far and had the front of the teeth filed back but then got pulled in and frozen while the flywheel ate it up. This happened on a new flat tappet engine so I had the throttle rigged to jump up to 2500-3k rpm so it happened quick. Haven't pulled the stock one back out again, yet.

302, T5 with correct bellhousing (came with trans), 157 tooth flywheel and yes, block plate too.
Started out with a DB Electrical mini-starter. At first assumed I had an electrical issue due to the PM motor but not the case. Swapped in a stock 1990 standard style, single cable connection unit. Same deal. I've measured the depth of the flywheel from the block plate surface and compared to the seated bendix gear position and those measurements show adequate clearance. Still does it. Found out about a starter shim for Fords (never in my life have I had to use such). Installed one (.100" thick) to move a bit farther back. Still happens.
What the hell am I missing?
Here is a pic of the carnage done to my original mini starter. It looks like the gear sat in just a bit too far and had the front of the teeth filed back but then got pulled in and frozen while the flywheel ate it up. This happened on a new flat tappet engine so I had the throttle rigged to jump up to 2500-3k rpm so it happened quick. Haven't pulled the stock one back out again, yet.

...yeah, I know...I removed a few thousandths of material on the outside section of the block plate hole to allow me clock the starter a very minor amount to decrease the gear mesh a a few thousandths. Seems to have cured it. At least the time I just tried it. To late to fire it up now. Neighbors. Will play more with that in the morning. Let's hope this one is licked. Nothing is ever easy on this car.