Due to excessive blowby and very little power to move itself, I replaced the sleeves, pistons, and rings with a 3 1/8 kit. I also had new valve guides put in the head. PROBLEM It ran for about 5 minutes, not good but it ran. I shut it off and now all it wants to do is backfire through the carb and does not want to fire like it should. The tractor WAS running before any work was done.The magneto was NOT removed and the timing is correct at TDC. The valves have been adjusted three times. It now has new Autolite 3706 spark plugs. It now has a new distributor cap and plug wires. I've verified the plug wires are NOT crossed. The carb has been removed, cleaned, new float valve and seat. The fuel mixture screw was NOT adjusted. I've installed a different magneto and still have the same results. The crank and cam were NOT disturbed. All of the valves are operating correctly and the intake and exhaust are closed when #1 is at TDC for timing I've restored 2 F-12's and 3 F-14's and this one has me stumped. Knowing how the cam gear is fastened to the end of the cam and how it is driven from the crank I don't see how it could have gotten out of time. But is that what I need to do next? Pull the front cover and have a look? Any ideas?
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