1968 impala 307 starter problem

My friend picked up a nice 307 with powerglide. I checked the casting and engine numbers on the block and it appears it originated in a 1968 Impala in a std trans. We installed it in a 12 passenger snowmobile last week, replacing the 6 cyl in line flathead that they came from the factory in. With a lot of fabricating it went in all right. We added a HEI distributor but otherwise it is stock I believe. The starter supplied from the auto wrecker he bought the engine from was obviously wrong and didn't meet the ring gear. They replaced it with a newly rebuilt one with the vertical mounting bolts across from one another and it looked ok but when installed it doesn"t engage consistently. We took it back and they say it is good and questioned our 12v amp supply at the solenoid. I put a relay in line to make sure the power was there and I even grounded out the solenoid with a jumper and still only catches and stays in about once in four. Runs great buit we have to figure out this problem..Is it the bendix, ring gear??? any ideas would be appreciated....

a 12 passenger what? can you post pictures of this?

as for your question, just sounds like a bad 'starter', the whole unit for a SBC is like $50 or less so go get one.

Thanks for your reply. Forum rules seem to indicate no attachments so I likely can't post photo of the machine. Will try to put in profile...

Well you were right, bad starter. The supplier disassembled, put on another sloenoid/bendix and away she went. Starts excellently as soon as starter engages. The only timing info I could find shows 4 deg before but it seems to need about 8 to run smooth. Will be fine tuning that after we get it operating in the field with just enough to prevent pinging. WE expect to have to add octane boost and lead additive as that engine was not designed to run on low lead we now get in Canada?