Timing is probably not the issue. The starters may not be fitting up properly, make sure that you aren't missing any spacers. Also if you are using the same brand for replacements, then check to another brand as there could be a bad run of starters.
Its probably a bad flywheel
the teeth on the starter could be worn out or the teeth on the flywheel could be worn out ... hopefully for you its just the starter if its the flywheel you will have to pull the tranny ...
Bad Ring gear (flywheel)?
Some starters are intended for a 153 tooth flywheel, some for a 168 tooth flywheel. Most 307's had 153's, and most 350's had 168's, but you could put a 153 on a 350 or a 168 one a 307. Both engines are internally balanced, so as long as you have the correct starter for the flywheel, it will work. The one other difference between Chevy starters, is the length of the armature. The longer one is heavy duty, the shorter one is standard duty. Either will work as long as it's mated with the right flywheel.
I'll let you know when I finish the steel flywheel I am making and test it out. If possible, i am going to run up the flywheel until it explodes, so I know a relatively safe speed to be running flywheels at in the future.
You could try phlox for starters
possible that it was inproperly installed or needs replacing and it could be the clutch to so open er up.
Starters can fail over time, or a broken tooth on the flywheel could be causing a bind. If the starter is failing over and over and is an aftermarket type, then it may be necessary to change back to a factory starter replacement.
yes. a starter made for the 168 tooth flywheel would not engage a 153 tooth flywheel.
if shes not eating she could have upper respritory infection, which is what mine dyed of. Get your bunny to the vet as soon as possible!!
Bad starter, bad flywheel/ring gear, bad starter/flywheel alignment.
Defective starter, or a problem with the flywheel. You need to check the starter and then remove it and check the flywheel.