Big Block motor mount shims

[David D.]

Can someone tell me the purpose of the "V" shaped motor mount shims used on my 1972 454? I do have factory AC on this car and I was told it had something to do with the AC but I just don't see how it would affect it.

Thanks,
Dave

[Terry M.]

Re: Big Block motor mount shims

Can someone tell me the purpose of the "V" shaped motor mount shims used on my 1972 454? I do have factory AC on this car and I was told it had something to do with the AC but I just don't see how it would affect it.

Thanks,
Dave

If you have a Mark IV with C60 you should have the fan with blade tips that extend beyond the edge of the shroud. If that fan is not centered in the shroud those tips will hit the shroud and you will find out how hard it is to find another undamaged fan with those tips. The shim(s) center the engine and therefore the fan in the shroud opening.

[David D.]

Re: Big Block motor mount shims

Thanks Terry,
I do have the Mark IV with C60 and I did have to Adjust/Shim the fan shroud to keep the fan from hitting. So I got around the issue when I re-installed the motor without the shims. I have the shims, they were stuck to the old motor mounts and I didn't realize they needed to go back on. Guess I'll try to jack up the motor and squeeze them in.

Is there also some affect on the carburetor float level? I had someone tell me that it may affect it as well??

Thanks,
Dave

[Terry M.]

Re: Big Block motor mount shims

If the fan is centered in the shroud opening without the shims -- be happy and leave well enough alone.

The shims could affect the float level slightly, but they are not thick enough, IMO, to make any substantive difference. I am pretty sure their sole function was to center that fan. It is a very tight fit in the shroud. Be sure your engine mounts are good, and continue to stay that way. A broken engine mount is another way to bugger up that fan.

[Joe L.]

Re: Big Block motor mount shims

If the fan is centered in the shroud opening without the shims -- be happy and leave well enough alone.

The shims could affect the float level slightly, but they are not thick enough, IMO, to make any substantive difference. I am pretty sure their sole function was to center that fan. It is a very tight fit in the shroud. Be sure your engine mounts are good, and continue to stay that way. A broken engine mount is another way to bugger up that fan.

Terry------


.....and since those "spiked-tip" fans have aluminum blades, they damage pretty easily.