>>What instrument would be used for performing this test? Where would I be >>able to purchase it? TIA It's an air perssure gauge that's atached to a hose that has a threaded end for screwing into the plug hole...then you crank it. (I think it would be a good idea to remove all the distrib. wires tho. (hey, don't want to not say the obvious and have bad things happen..) -J