Turbo 6 into V8 g-body or vice versa...

[SinistrV6]

What I want to know is; what's the difference in the motor mounts/crossmembers. Even though these cars came with 6's and 8's, I'm assuming that their not interchangable without different mounts. Am I correct?

 

[TurboDave]

Originally posted by SinistrV6
What I want to know is; what's the difference in the motor mounts/crossmembers. Even though these cars came with 6's and 8's, I'm assuming that their not interchangable without different mounts. Am I correct?

The motor mounts on the G body's would be the same. The Tranny crossmember mount may or may not be different depending which tranny the car originally came with.

 

[GNVAIR]

Each type of engine used in the G body had its own specific mount. The V8 Chevrolets had the rubber mount bolted to the frame with the steel bracket bolted to the engine. The Buick V6 has the steel bracket bolted to the frame and the rubber mount bolted to the engine. I did this swap on our Monte SS and went through this.
There are approximately 4 different trans crossmembers (more if you go by GM part#s)
The crossmembers can be:
TH200c/TH350 V8
TH200c/TH350 V6
TH2004r V8
TH2004r V6
The different between the V8 and V6 crossmembers are the transmounts are offset to the passenger side and the mounting holes in the crossmember where they bolt to the frame are oversize for vibration isolator pads.
I ended up using all the stuff from another GN to do my swap.

 

[SinistrV6]

That sort of answers my question but....

What I was getting at is this... My '36 Chevy already has a small block and TH350 mounted in it. It's an aftermarket motor mount/crossmember and a homemade (UGLY, gonna get replaced) trans. crossmember. Are the V6 and V8 motor mounts in the same relative place on the motors? Width and distance from firewall? I can put one of my 109 blocks up there and check it but typing is easier than putting in motors !

 

[GNVAIR]

The V6 mounts sit further back on the frame. The V8 Chevy mounts in a GM body actually hung off the front edge a little bit. The V6 mounts sit towards the back edge. To give you an idea here; the Buick V6 mounts are similar in design to the pre '73 Chevy mounts with the rubber being bolted to the engine and steel to the frame. The later Chevy mounts are what they call a "clam shell" design. GM redisigned them after Ralph Nade slammed them in Unsafe at any speed. Supposedly GM had a problem with engines ripping off the mounts in frontal collisions and coming into the passenger compartment.