Motor and transmission mounts

[PhillipM]

I am working on making some custom motor mounts for a project and I have the engine mocked into place. What is the best way to know that after the rubber engine mounts compress the engine will be where I want it? (I am using GM rubber locking engine mounts) I was thinking of just throwing an extra .25" of height on it and hoping for the best but that doesn't sound to sure.

What brought this about was a transmission mount that I did for our Olds, after I got the mount done and let the trans down it compressed about 1/4" and wasn't where I wanted it to be.

Anyone have any experience with this??