[propane1]

Late timing will cause the engine to run hot. Noel

Weird the same tractor too !!!!

 

[ODN]

Pretty crazy you and Noel have the same damage on the head, Derek! If that spark plug in your head is the one you were running, it sure looks like an extremely lean fuel mixture. That will make hot spots to the point of possibly melting things, especially thinner aluminum areas. Your pic has the lighting about right to see deep into the porcelain recess, and it looks pure white all the way. Maybe there's a restriction in the fuel somewhere?

DAC

Late timing will cause the engine to run hot. Noel

Weird the same tractor too !!!!

He replaced the carb on it, not sure how long ago, and said it was adjusted by a small engine mechanic. It started easily, ran well (albeit with a slight engine knock at high speeds), would go from full throttle to idle without so much as a sputter, so it seemed to be well adjusted. Once I have a head for it, I'll do a better valve inspection, check points and replace/set as necessary, check timing, set up carb, fresh oil, and add either some transmission oil to the crankcase to loosen things up and/or try the Marvel Mystery Oil in the gas that Rick suggested in the first reply. I don't have a heated garage, so if I can avoid stripping it down at this time of year, I'd prefer it. I am concerned about that engine knock, though.

Derek

 

[propane1]

Depend on the noise. Some of my engines have knocks or ticks and have been like that for years. Some sound like they are going to fly apart any minute, but I had a nice running kohler 12 hp without any noise and it split the piston in half. Broke at the oil ring groove. Noel