Originally posted by terry sturchio
If it crushes the plug you most likely will have internal engine damage at this point. Adding a shim to a damaged engine would be a mute point. Typically, you don't need to add shims unless the engine starts to detonate or prematurely ignite in the stroke. This is caused by excessive compression and can be relieved by the shim gap. It's usually more of a problem when the temps climb outside or you are running fairly lean engine settings. You'll know when it starts to detonate, it makes a distinct crackling noise in the mid to high rpm range. If you hear this shut it down immediately and add the shim. Inspect the plug and check the top of the piston for pitting at this time as well. If the plug is blown or the piston is pitted, tear the whole engine apart and inspect it for damage or particles. Detonation for a sustained time usually results first in a blown glow plug, which can damage an engine in a hurry if the coil gets stuck between the piston and a port. Not hard to do at 40000+ RPM's.
Very true...
Remember that to get the longest life out of your motor you will need run it in again with the new fuel. remember that when you change the fuel, you are changing the equasion insitde the engine, ie: higher or lower temp combustion, more or less oil, you get the picture I am sure.