ok its a 8hp tecumseh the 1s with the smaller pistons the red 1s not the white but anywayi just put in a crank that is about 1/8in or so bigger so the piston raises higher but i got the head milled right and it wouldnt run with the timing stock so i retarded it 1 tooth on the cam and it ran but crappy and would only start with choke and run when furiously moving throttle back and fourth with elec start so i retarded it several imes up to 4 teeth back with the same results i beleave there is a head leak but anyway wat should the timing be with that crank and mild porting also tuning dosnt help