Need help with motor mounts

I'm getting ready to install the engine back into my completed chassis and I need some help with motor mounts for a small block in my 78. When I removed the mounts, I didn't notice that they were not the same on each side. One of the mounts measures 2-3/4" inside and fits snugly onto the frame horn. The other mount measures 3" inside (between two 1/8" spacers) and of course has about ¼" of "play" when mated to the frame. This mount also has oblong holes where the frame mounting bolt passes through it.







Is one of these correct and the other one wrong for this application? When I look up replacement mounts I see the same part numbers listed for right and left.

To complicate things, I have a mount from my 79 parts car and it is different from the other two. This one also measures 3" inside, but there is a ¼" spacer on one side only. It would seem to me that using this mount would change the driveline angle, no?



What is the correct thing to do here? Which one goes where? :banghead:

I don't know what is what, except to say, that wider mount with some spacers would certainly solve a mystery I have had with my car for 15 years now....

on the driver's side, the mount seems to be always a 1/4" off on location to the frame horn....makes the tranny tail set too far to the driver's side....

I just pry it over and be done with it.....unhappy with doing that, but it's never been an issue I can see, except I did have to replace the driver's side mount once.....

I too am curious to see WTF....

Yea Gene, this has me perplexed. These are the mounts that came out of my car, but this is a project car that I did not drive before it became a pile of parts. The PO installed a crate motor, so it's possible that the mounts could have been changed at that time.

I'm sure there's some collective wisdom around here that can shed some light on this.

It seems that the Camaro boards have a lot of information on motor mounts. C3 small blocks use the same mounts as 67 - 68 302 & 350 Camaros.

I found the correct mounts in stock at Advance Auto. For future reference if anyone else needs these, they are Anchor part number 2285.

The mount on the left in my photo is the correct one.