Block to Bell Housing Bolt Pattern
 

I've searched this site using all different search terms and couldn't find these dimensions.

Is this the correct drawing for a mid 70's Pontiac block?

Are they calling out bellhousing bolts as 5/16-18? I'd have expected 3/8-16.

Other than that, that seems to be all correct for the bellhousing bolt pattern. Not sure about the flywheel bolt patterns.

That’s anything but a Pontiac block.

The dimensions are different that they give and besides that look at the 4 water jacket frost plugs seen behind the flywheel.

Pontiacs only have two on each side and there higher up.

The casting about the 7.07 dimension doesn't look right. I think it be smoother angle and no lip. Could be Buick or Olds.

Even if it was a B or Olds block the bell housing bolt holes would be 3/8” .

This is from Gavin (I believe) :


:)

I just cut a fixture last month utilizing these holes and can verify them to be true.... so I assume the top ones are too.


Kris.