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Due to starting problems, I replaced the camshaft on my Craftsman 18 hp lawn tractor model 917.272754. It starts every time now but will not throttle up and runs loud and somewhat rough (this was not true prior to this repair). The throttle lever visually appears to be working correctly. I did some research and wondered if I should have checked for TDC before aligning the timing marks on the cam and crank. I just dropped the cam in when the two marks lined up. I read about the possibility of being 180 degrees off on the marks since one gear is twice the size of the other if TDC wasn't verified. I am looking for information about this possibility before taking it apart again.

Briggs and Stratton engine 31H777 0202 E1

Thanks.

I would check the governor to make sure it’s adjusted correctly before I tore into it. I’ve never worried about tdc as long as the marks line up your good.

It can't be 180 degrees out, the cam turns at half the speed of the crankshaft so rotate the flywheel a full turn to line the marks up. To verify cam timing rotate the flywheel until the exhaust valve is closing as the intake opens, the piston should be at top dead center. Did you set the valve clearances correctly?

Romore said:

It can't be 180 degrees out, the cam turns at half the speed of the crankshaft so rotate the flywheel a full turn to line the marks up. To verify cam timing rotate the flywheel until the exhaust valve is closing as the intake opens, the piston should be at top dead center. Did you set the valve clearances correctly?

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Thank you. After more research, I realized that it can't be 180 degrees out. I think I set the valve clearance correctly using the specs from my book and after locating TDC through the spark plug opening, but I will recheck. I guess I thought it wouldn't start at all if I had messed up setting the valves. Before replacing the camshaft, it ran smoothly and throttled up to full speed when it did start, so I know I messed something up.

Thanks, Mowlife. I will read up on the governor setting next. I am a rookie at this but learning lots.

Definitely read up on it. You must adjust the governor after a cam swap....assumed you did and was recommending you double check it.