are they comparable to rubber as far as the vibrations, etc. I am thinking about putting in some poly mounts. I currently have the Z28 style that are only 2 years old, and while the motor is out, i was thinkin about it. Is it really worth the hassle of taking my mounts off?

thanks
mike

They should be close. If you were to rate them on a scale of 1 to 10, with 1 being rubber, and 10 being solid I think they'd come in at about a 3. Old rubber mounts are probably also a 3 due to the fact that they have compressed and don't have much give any more.

But then again, I may just be talking out my butt.

i may put them in, just i hate replacing them.

any good ideas on replacing them. we cut a hole in the k member and welded a plate on it. i their anyway to reach the bolts while the car is put together.

You'll probably never have a problem "ripping" a rubber mount in half on your 81 since it is fully encapsulated in a metal shell on the frame side (unlike many cars from the muscle car era). GM still uses that same basic design on many cars today. However, they will let the motor rock around quite a bit and the rubber can still wear out, collapse and leave the motor sitting kinda "crookedy" in the engine bay.

I agree that on a scale of 1-10 poly mounts are about a 3-4 vs. a solid mount.

I don't know the longevity of poly motor mounts, either. Only short term experience with them.

Poly in my car for four years, look new, work great.

i am just debating it if is worth the hassle. i have the z28 mounts i put in about 2 years ago and only have like 2000 miles. i know how much of a pita it is to change them. i am hoping to get the engine stuff back tomorrow afternoon and get the motor put together and back in on sunday.

I'm going to say no. If you think it is a hassle to change them, and you have relatively new mounts installed, then just leave them. It won't make enough of a difference to go through the trouble.