Starter not engaging
 

trying to tune a new 455 build in my '67 GTO. Starter is not engaging the flex plate.. Its a new mini starter from Summit. I installed it per the instructions, checking the pinion to flex plate distance and the pinion to flex plate teeth engagement. Used two shims get it where I thought it should be. Tested it with the coil wire ( so the engine wouldn't fire), it spun the engine and sounded fine so I considered the install good. Fast forward to the engine tuning session a few days later. On the initial turn of the key to the run position it started right up but I had to shut it down a few minutes later due to trans fluid leak. After fixing the leak I tried to start it again but this time no crank, only the sound of the of the starter pinion firing. I got under the car to check it out while my buddy turned the key and I could see the pinion fire out and but not enough to engage the flex plate and crank the engine. I may pull the starter and bench test it but other than that I don't have a plan. Sorry for the long rant and let me know what you think. regards.

Is the drive gear hitting the ring gear and stopping or does it engage the gear but not turn?

it appears and sounds like it is hitting the ring gear,. I dont get it, worked fine when tested with the coil wire removed. I have tried to pry the pinion out with a thin blade screwdriver to recheck clearances but It wont come out.

I just went through the same process with a new IMI starter from Ames with no problem. Have you tried bench testing the starter to see if it will actually work? It's possible something broke.

The bolts were torqued to spec. I know it didn't move. Took it out and bench tested. Works great. Reinstalled without any shim pack and tested the pinion engagement using a temporary lead. connected to the battery cable. The pinion fired right out with good engagement on the ring gear. Hooked up the battery lead to the starter and turned the key. Engine fired right up. Shut it down, tried again and she fired again. I suppose the clearances must have been off enough with the shim pack to cause interference Thanks for all replies.