[sailchef]

The tolerances of engine parts will be closer on a "hot " engine because of expandtion and will give you better numbers. A "warm" engine is good, "hot" is better.

I just purchased a Leak down tester from Harborfreight.com. $29.95 + shpng. It has two guages, adapters for the plugs and looks to be made very well. I havent used it yet so cant say anything about that.

good luck with your project.