Starter motor 2bolt or 3 bolt big block

[Ted K.]

My 1966 427 starter motor sometimes fails to engage and just spin. Decided to check it out. The existing starter had 3 bolt holes for attachment but only 2 of the holes were used since the third hole in the starter did not line up with the 3rd hole in the block. What is the correct starter for a 1966 427 450? I assume it is a three hole starter which mine was but all the holes did not line up with the three holes in the block.

[Mike T.]

Re: Starter motor 2bolt or 3 bolt big block

Ted - Any GM part numbers stamped in your Bigblock starter? I'm out of town right now and can't take pics of the GM starter on my 66 L72 but will check when I return. The starter on the 427 in my 65 L78 wont help here as it's an aftermarket version. Going off memory only, probably not a wise choice at my age, I dont ever recall using three bolts to secure a Bigblock starter.
By the way, any chance your starter motor is good and its just the starter drive, what we used to refer to as the "Bendix"?

[Ted K.]

Re: Starter motor 2bolt or 3 bolt big block

The bendix looks ok, I might need to utilize a shim to prevent the spin. It just seemed strange to have a starter with three bolt holes and a block with three bolt holes but only two of them line up.

[Mike T.]

Re: Starter motor 2bolt or 3 bolt big block

If the starter isnt new and this no-start (or free wheeling spin sound) is a new development, I might still be looking at the Bendix as the culprit, since the clutching mechanism is internal with nothing really visible on the exterior.
Is there a chance that the starter is too far from engaging the flywheel ring gear, and it doesnt happen that often compared to being too close, by just shimming the outer bolt, you can shift the starter closer rather than further away.

[Stephen L.]

Re: Starter motor 2bolt or 3 bolt big block

1967 427/390 L36. Original starter has 3 holes for mounting. Only 2 are utilized.

[Ted K.]

Re: Starter motor 2bolt or 3 bolt big block

Thanks, the picture looks like mine. I will try using the shim on one side.

[Mike T.]

Re: Starter motor 2bolt or 3 bolt big block

Maybe use a Black magic marker on the Bendix gear...all over it and then. try starting the car to see roughly how much engagement you actually have. I believe theres supposed to be a .040 gap at the bottom of the teeth when they mesh correctly. That measurement is easy when the engine is still on the engine stand...not so much once its all buttoned up and in the car.