Hi All!
Working on installing a big block in a 69 Camaro. Having some clearance issues. I know there are two different sets of big block frame mounts for the 1st gen Camaros. Why is that?? The sub-frames are interchangeable right? Why did GM make the change? Are the frame mounts all interchangeable as long as you use the corresponding motor mounts? Can you use the 67/78 BB frame mounts on a 69 sub-frame? Thanks for any info to help clear this up.
John

In the late '60s Chevy had one of the largest recalls in history due to bond failure of the LH motor mount. When the mount failed the engine would lift off the frame binding the accelerator linkage. The recall involved placing a tie-down cable from the exhaust manifold to the upper control arm.

For '69 Chevy intoduced a new interlocking motor mount. It was taller than the '67-'68 style mount and required new frame brackets. The new mount and brackets were used on all bbs but not all sb: only the Z/28 and 350s used the new bracket & mount. 307 & 327 used the earlier design.

For the most part your assumption is correct-as long as you use the correct bracket & mount combo everything should fit. The most common problem with this is the 67-68 non-interlock mount fits the 69 bracket. It is a sloppy fit, the engine will be positioned too low. You will have clutch chatter and driveline vibration. The correct motor mount is always a tight fit on the bracket. If it is not you have the wrong parts.

Didn't early 69 b/b use the non-interlocking motor mounts? I used the 69 engine mount towers with a set of NOS non-interlocking mounts on my 69 b/b. I also have a set of NOS interlocking ones, but they are thinner. With the thicker ones, my fan aligned properly on the shroud. I wanted to use the interlocking ones, but was afraid that since they are shorter, I would have a problem with the shroud and fan.

I will be reinstalling the motor in the next couple of months, and if I should be using the interlocking ones, now's the time to know. Any advicce?

PS I was planning to put a lift stop kit on the engine. I have one for a s/b with A/C that attaches to the compressor. It will fit my b/b with about a 1" extension bracket. between the cable eyes and a bolt on the compressor. It's been awhile, so I don't remember exactly, but I do remember it was going to be a easy solution. I have never seen one for b/b with A/C, but I haven't really looked for 3-4 years.