Before I commit to bolting the motor mount perches to the frame, can someone tell me if I have them in the right location? Also, would it be possible that these perches are for 307 block? The final product will be a 1968 Chevelle with a 396 BB so I'm hoping I have the right set.

Dan

Go here. Photos and explaination of the difference between the two kinds of frame perches... http://www.flickr.com/photos/10058179@N05/sets/72157602905641952/detail/

I just checked the part numbers on my mounts and they are #3980707 and 3980708, or for a 307 block..........I guess I'll be shopping around for a set of BB perches. At least I had them in the right mounting holes!!

Dan

Just keep in mind that BB's and 350's all used the same frame stand mounts. If you can find someone parting out a 350 car, you're golden...

There are a lot of post about this .a couple months ago I put a bb in my 70 chevelle ,originally a 307 car but changed to 350 so ireally did not know what was what.I went for it with what I had and everything fit fine.Here is a drawing I made at that time of my mount heights.

It appears that the 307 mounts sit a bit higher up than the BB mounts. I'm running a 700r4 transmission and I want the engine to sit as low as possible to avoid the transmission housing from hitting the underneath portion of the car, otherwise the additional height would not bother me.

Dan

I just went throught this due to the fact that my fan runs very close to the shroud at the top. my car was a 307 car & I was led to belive that changing to 350 frame brackets & mounts would solve the problem. Well after struggling to change the mounts/brackets over to 350 ones, I gained... nothing. The 307 frame bracket sits taller but the 307 mount is shorter. Maybe the only benifit to be gained is a stronger mount with the 350 mount? I don't know. But then again when I did the swap I used lakewood muscle mounts & those things are Gynormus!

Brian - I think you are correct that swapping the stands won't really gain you anything. However, the BB motor mounts have the interlocking system on them (in case the rubber breaks) but I can't say for sure if the 307 mounts have this.

You can mount any small block or big block on 307 frame stands as long as you have the 307 motor mounts. If you have the BB/350 frame stands, you must have BB/350 motor mounts.