I have 1972 Cutlass S that has a 350 Rocket in it still. I measured the Clamshell mount and it is small in the shell portion of it and its approx. 2 3/4" between the motor mount where the bolt is located. The stock mount itself is pretty thick. Is this meaning I need to get the Tall and Narrow style mount? Energy Suspensions dimensions compared to the measurement I took, neither of their mounts would fit the dimension. Do you have to pound them on?

Also, I have noticed some people swapping clamshells so they can use short and wide mounts, is there any benefit to using that set up with a short and wide bushing instead of using what I have and a tall and narrow bushing? That only thing I can think of it over time there may become more flexible because the bushing is thicker. But having a thicker bushing would also allow it to be more vibration dampening.

 

Are you trying to adapt to the Olds frame mounts? If so, that wont work.
The Olds mounts are very wide, low and to the rear. I doubt any motor plates woud adap easily.


Good news is every Olds frame I've seen is drilled for chevy frame mounts. I picked up a couple chevelle frame mounts off ebay for $20.


There is a company that sells an adapter that bolts to the original Olds 3 bolt holes, but the chevelle mounts are an easier solution.
http://carshop.carshopinc.com/produc...110328/CSP2380

 

I don't know if olds mounts are the same as small block chevy mounts so this strickly applies to small block chevy mounts.

You can't interchange the two style sbc mounts unless you cut/weld the frame mounts to fit. The overall height of each pair(engine and frame mount) is the same. The purpose of the wide motor mount was to keep the torque of the larger motors from pulling the mount apart over time. The short mount also has an interlock built into it so that if the mount was to seperate the engine could not lift under accleration. If you haven't seen a motor lift with a broken mount you would be surprised how high it will.

If using the tall/narrow mount, use a performance aftermarket one as most have been redesigned to include an interlock. Check with the manufacturer first. The other benefit is a cleaner appearance and allowing more clearance for headers.

IMO, best bet to fit the engine is to get and adapter for the engine mount and then redrill the frame mount once you fit the engine in the car. You can then move the engine forward or back depending on the offset/setback you want with you tranny combination. You will likely have to shim the frame mounts with 1/4-1/2" plate for oil pan clearance. Yes this means you have to install the engine a couple times to get everything set right. Either re-drill the frame or tack weld them in position and weld after pulling the motor.

One way to eliminate shimming with plate steel is to modify a tall(wide) frame mount for use with a tall(narrow) engine mount. This combination results in approximately 3/8" height differance than the original combinations. Or make your own frame mount with 1/4" plate and DOM tubing to set the height.

 

When I did my Chevelle, I used the Tall and Narrow mounts with Short/Wide Frame stands on my Chevelle. I took the S/W frame stand, narrowed them (Cut/Weld) and was able to get a bit more height for more clearance for the Pan and Steering ends.

Not hard to do.

You just need to see what lines up and mod anything needed to make what you got work. But if the Olds stands are in the wrong locatoin, Picking up a set of SBC ones is a cheap and easy solution.

BC

 

Garys 68: Yeah I noticed that I have a few extra holes that are farther forward than the other mount.
I don't really know anything about welding so I don't think I will try and modify any mounts.
I think I will try and find a used set of 307 frame mounts and get a good set of short and wide motor mounts. Thanks guys.

 

I just bought some fully adjustable mounts off of eBay from a company called Dirty Dingo. They made sure to ask what my specific application was so that the engine mounts they send will fit whatever mount is on my frame.