Originally Posted by flybyjohn

All right. Just had a quick run with it. No Cetane boost yet but added some more load the Redneck way. Not sure just what the load is that I added but should be sufficient. I am running 30% ether , 25% caster and 45% Kero/heptane. I was able to get it to run fairly smoothly. There was a lot of what sounded like knocking until I increased compression some but then most knocking went away and was able to pull right at 7000 rpm and then could go to about 8000 rpm with a little more compression but started hearing a different knock so backed off compression till just got a miss and then leaned it just a bit to smooth it out. Could idle about 2000 rpm, probably less but didn't have a proper setup to hold the throttle well. Took the head off again and the contra was just a little tint of brown, a lot less brown than it was last time I ran it. I found that without the tension on the adjustment screw, the contra screw will back itself out while running. I will wait until I get the cetane boost in before running again. I think I might just have this figured out.

Here are some pictures of my load and the under side of the head. The mark on the piston is where the broken rim on the old contra contacted the piston.