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I have two 69 Chevelles, a hardtop and a convertible. My hardtop has a 1975 350 engine and when I recently switched out the auto trans for a 4 speed Muncie, I installed an 11" clutch, so I had to get a new starter to fit. The bolt pattern on the new starter has a diagonal 2 bolt mounting. While flipping through the pages of my assembly manual, I noticed that the original mounting for a V-8 engine (they make no distinction for any cu in size, just V-8) is 2 bolts in line with the back of the starter. Then, when I checked the convertible, which has the original 350 engine, I was surprised to see that it had the diagonal mount pattern. Does anyone know why this 350 engine would be different from what is shown in the assembly manual?
Thanks,
Rich
 

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Some starters have accomodations for both diagonal and parallel pattern. You should be able to go to your parts house and have them search for the right one, it shouldnt be too hard.
 

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Rich,
Read the following carefully!!!!!!!!
OK, ready?
Starter mounting and starter bolt pattern (straight across or staggered) IS NOT, repeat, IS NOT related to ANY size of engine (V8 or 6cyl)!
The starter mounting and bolt pattern is DIRECTLY related to the size of the flywheel/flexplate.
There are ONLY 2 sizes of flywheels/flexplates: small, 153 teeth and big, 168teeth. That's it, that's all, there are no other sizes or tooth count flywheels. PERIOD.
The small flywheel requires a starter with a straight across bolt pattern.
The big flywheel requires a starter with a staggered bolt pattern.
That's the ONLY way they go together. PERIOD!
ANY, ANY, ANY Chevy V8 engine (and straight 6cly beginning in 63) can accept EITHER the small or big flywheel.
There were 2 engines which ONLY came with a big flywheel, without exception. They were the SB400 and the 454BB. The reason is because both of those engines used an UNbalanced flywheel which had a big weight on one side for balance purposes. These UNbalanced flywheels (or flexplates) ONLY came in the big, 168 teeth version.

But wait, there is more.
As I mentioned, the big flywheel requries a starter with a staggered bolt pattern. BUUUUUUUUUUUUUUT, for an engine with a manual tranny flywheel, you must use a starter with a CAST IRON nose. The starter with an alum nose and staggered bolt pattern WILL NOT fit into the starter bulge of the big bell housing (Oh ya, I forgot, there is also a big and small bell housing for manual tranny flywheels).
ALLLLLLLLLLLLLL of the above is specific to original style GM Delco type starters. The mini starters may present a different situation.
If you need pictures, let us know, we can furnish them.
 

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Thanks for that explanation Tom. I would guess then that every engine (with the possible exception of the SB400 and BB454) had 3 holes drilled to accept either starter depending on whether it got a small or large flywheel. Correct?
Thanks,
Rich
not all blocks are drilled for both patterns, as i discovered when i had the stock motor out of my Monte a few years back and decided i wanted to put it back together with a small flexplate so i could use my LT4 Corvette mini starter on it. i got the engine in the car and bolted down. the trans and torque converter bolts were all in.. then i went to put the starter in (straight across pattern for the small flexplate) and the inner hole wasn't drilled in the block.
so i had to unbolt the trans, converter, and motor mounts and lift the motor back out to swap the stock big flexplate back on.
i think this was a cost cutting measure they instituted in the 70's to try and save a couple of bucks on each car they built. i knew there were 400's that only had the staggered bolt pattern, but mine was the first 350 block i found like that.
 
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