Motor warm, Pull both plugs, and kick it repeatedly very fast with the trottle wide open the whole time. As long as you measure the squish at the side of the rod pins, then use your lowest number (.045") it should be ok. Now, the key is to see if your compression is actually what the gauge says it is. If its detonating, you can back off timing, or up the octane to get rid of it. If the plugs back out on their own, thats a sure sign that it is detonating.