I need help with new top mount starter

[Nubbs]

Ok, I've got some issues here. My boat had a bottom mount starter, but it went bad. I decided to replace it with a top mount starter. It's a BBC with hardin marine bellhousing/mount. I bolted the starter in with no problems. When I cranked the motor over, it made this awful screeching sound. Also, the starter didn't disengage completely. I played around with some shims and got the starter to disengage, but it still made the screeching sound. Will this awful noise go away with some use, or do I have a problem? I've never installed a brand new starter before, so I'm a bit stumped on this one. I almost forgot, I'm supposed to leave for Havasu early Thursday morning too.
Nubbs

[Rexone]

Screeching isn't a good sign nor normal. When does the screeching occur? Depending on starter type, the aftermarket small starters come with shims to set clearance. You need clearance both away from the flywheel both length and height (proper tooth clearance when engaged). Unfortunatey with top mounts you many time can't get the height right easily. And with stock type starters they usually don't come with shims anyway.
I've seen bellhousings machined slightly wrong too causing never ending starter issues.

[Nubbs]

Screeching isn't a good sign nor normal. When does the screeching occur?
Screeching occurs when the starter is spinning. The solenoid will kick the gear out and then the screeching starts with spinning. The starter is a delco type top mount, purchased from Rex. I thought I read it's made by Sierra. It sounds like I may have to remove some material from my bell housing in order to set the height correctly. Do top mount starters require a special bolt?
Nubbs

[Rexone]

Screeching occurs when the starter is spinning. The solenoid will kick the gear out and then the screeching starts with spinning. The starter is a delco type top mount, purchased from Rex. I thought I read it's made by Sierra. It sounds like I may have to remove some material from my bell housing in order to set the height correctly. Do top mount starters require a special bolt?
Nubbs
My guess would be not enough tooth clearance (this is a guess not gospel). Does the gear hang at all when you release the start button / switch or does it kick right out? Yes it's a Sierra if you bought it here. We've had good luck with them. No special bolts I'm aware of on top mounts as the starter housing registers in the bellhousing hole. Yes definately on bottom mounts as the shouldered bolts make the alignment correct. It's possible the bellhousing isn't quite right for starter alignment. You might try just loosening the bh bolts ever so slightly allowing the engine to settle a few thou possibly and then retighten them. Maybe will work, maybe not, easy to try it. That would spread the starter from the gear a little maybe. Kind of a crap shoot with these top mount bellhousings from what I've seen over the years with them, especially the Delco starter models (2-bolters).

[Nubbs]

My guess would be not enough tooth clearance (this is a guess not gospel). Does the gear hang at all when you release the start button / switch or does it kick right out? Yes it's a Sierra if you bought it here. We've had good luck with them.
Yes, the gear hangs when the start button is released. It does not kick right out. It's a Sierra. I had one on my last boat and it worked great.

[Rexone]

Yes, the gear hangs when the start button is released. It does not kick right out. It's a Sierra. I had one on my last boat and it worked great.
My guess is the bellhousing's a little off. Also make sure the bellhousing is good and tight on the engine as that would throw things off too if it was the least bit loose and sagging a few thou.
Does this bellhousing locate with the 2 large dowel pins in the block or are they missing or not part of the casting you have? Those if present usually locate the bellhousing dead nuts and if there was a problem with them present it would be in the actual machining of the starter location in the casting. If the holes are there but no pins I strongly suggest the pins be installed to correctly locate the bellhousing on the block. Parts house or Chevy should stock them. Also places like McMaster Carr. I've seen guys just leave them out because they're of no consequence if the BH only holds the motor up although I always still use them for support and alignment. Problem arises when you try to bolt a starter on. Just guessing this might be the case with yours.

[Nubbs]

Thanks for the replies. I'm not sure about the bell housing. I'll check it out later.
Nubbs