I bought some 72 frame side mounts( claimed to be out of a 350 car) and used them to replace sbc frame sides. Engine has the same passenger mount that came on it( 403 out of a 78 Buick) and I replaced the drivers side with a small block mount I had( the 403 just came out of my wagon which used the diesel motor mount). Over the years I’ve seen time again the big block vs small block( having to use a matched set) issues but I’ve never ran into it myself. Planning to buy new motor mounts anyways but want to make sure I’m buying the correct ones and I’m not sure my issue is in fact that I need big block engine mounts.




these are the frame sides I purchased.



if it’s not a mis-matched issue, what am I dealing with?

 

I did do some research before I purchased the frame side mounts.


it’s appears to me I did buy the corrects frame side mounts, car is a 72. This is only the second car I’ve swapped frame sides and had zero issues with my 66 going from 6 cylinder to sbo.

 

After further research it seems to me my issue could be because I’m using a b-body mount on the passenger side of the block. I’ll swap it tomorrow with another 2261 motor mount and see how I fair.

 

Every Olds motor built from 1973-1990, including 260s and 307s (and your 403) came from the factory with 2328 motor mounts, which is why I implore people not to call these "big block" mounts. Your 1972 frame pads need 2261 motor mounts.

 

Thanks for the confirmation, for some reason I was under the impression that all small blocks used the same motor mounts which is why I only swapped the drivers side mount.

 

And that's why I keep saying we need to STOP calling them "SBO mounts" and "BBO mounts".