10.4 on the leak tester, best money you can spend, I prefer the 2 gauge version, but a single will work also. I ck my nozzles at least a couple of times a year, just to make sure they are all flowing the same, or close, if you get a baseline off them when new, then you'll know when they are drifting, or plugging, but you can baseline them, even after being used a lot, and still tell if they are drifting. Real good investment! Bob

I'm definately getting educated! I researched the plugs that i believed came with the motor.I took for granted they were right but turn out to be passenger car plugs! I have gotten a set of champion racing plugs v59c which cross reference to Autolite AR-133 but am unclear what to set the gap at.The plug calls anywhere from 018-045.I'm using the old Vertex mag with internal coil.Any suggestions? thanks again, ron

Champion plugs come set at .025 out of the box.

Just another thought, while you are leak cking, look in the radiator for a bubble trail as you ck each cylinder, at a hundred psi, it will show a leak, might even blow the cap off, if you don't take it off. Those aluminum rads, are only good for about 40 psi, then they swell the tubes, closing off any air flow over them, another good thing to give a visual, if the fins look all kinda wiggly, look carefully at the tubes. Bob