David,

This seems to be a tired old engine kinda low on compression. My main focus was on the differences between the props. Also remember that the 11" and 12" props were Zinger wood props which will usually turn less rpm than an APC of the same labeled diameter/pitch. I'd expect the APC 12~7 would turn 11,000+ if I coulda got the engine started. Maybe I'll try again tomorrow after charging the plug driver overnight.

Terry in LP