Hi, well i finally got a motor for the '67 today. A rebuilt 350, and now i have a cpl questions. the guy at the place i got the motor from said to get poly motor mounts, because the rubber ones dont last. is this true? the rubber ones are about $5 a piece, and the poly's were $40. so i dont want to be spending a bunch of extra money if i dont have to. another question is will a flywheel from a '81 305 work on my 350? thanks.
Brian

The polyurethane motor mounts will hold-up better in an oily enviroment such as an engine compartment often is. Which is why they're better. For a street small block, they aren't mandatory by any means, however many things that we do to our cars in this hi-perf game aren't mandatory either. It's a matter of peace of mind, part longevity, and what your priorities are vs. your budget. So it's your call.

Me personally? I've used the Polyurethane motor mounts and transmission mounts on a 350 equipped car, and I like them. But if you're going to use them, it's probably a good idea to use the poly transmission mount along with them too, since they probably won't flex under load as much as the rubber ones do, and atleast in theory, that might spell trouble for your drivetrain if you're using a rubber mount for your transmission along with the Poly motor mounts. So IMO, you should either go with all rubber, or all Poly.

Use a poly on the drivers side only, that is the one that gets yanked on and will break first. works fine if you dont want to spend the money for all poly. Even lower buck is to use the rubber mounts and put an engine restraint on the drivers side to keep it from moving around enough to break a mount.