burtcs

I'm much too lazy to throw the depth Mic on the thing to get a baseline deck height, but...Adding or removing a head gasket does alter the deck height. The deck height is the part of the cylinder not used by the piston in it's travels, the head gaskets do contribute to that.

I'm viewing head gaskets as a compression ratio thing (the short, sweet and simple form). (piston swept displacement i.e. top to bottom dead center)+(Head volume)+(deck volume) / (head volume)+(deck volume) = Compression ratio. I don't know what the ignition point of 15% Nitro fuel is but I do know that by adding or subtracting a head gasket I can alter that point (I'm advancing or retarding the ignition point of the fuel). This will show up in the tach. readings and as you noted glow plug life. Until I add or subtract a head gasket, the ignition timing is just a loose cannon rolling around. Right now it isn't making any notable difference. I do think your right, the cylinder is still too tight.

A 5-3 prop eh? I just happen to have a rubber ducky I pulled off of a Holland Hornet; it's got the right prop hole in it. By now I really hate this engine it'll be fun to hear it squeal. Besides Norvel was dumb enough to offer a three year warranty. Hey I'm game, maybe tomorrow.

Regards - Steve B.