原帖由： dontlistentoquacks ,
Just like Mike I have a 17.5 HP Model 31C707 on a craftsman lawn tractor. But this information did NOT work for me, though it is the same as Briggs and Stratton -- https://www.briggsandstratton.com/na/en_us/support/faqs/browse/valve-repair-maintenance.html Well first of all, I had a bent intake push rod. The stud came loose and messed everything up. It even broke a rocker arm. So after spending a good hour trying to put the new push rod in the valve and getting them to stay (I finally took the valve guide off and stuck the rods in it, finally got them to stay and then carefully put the screws in) I followed this guide exactly. I set the clearances as Mike said. When I went to start it, the engine would barely turn over. So I asked the guy who sold me the parts how to do it. He said to turn the flywheel clockwise, the way it spins, until one push rod is extended out as far as it will go. THEN you set the clearance on the other rocker Arm. Do the same for the first rocker arm-- keep turning the engine until the other push rod is all the way out, and set the clearance. My engine started right up and runs better than it did when it was new. So I don't know what is going on, but I tried setting the valves as this guide here says and I tried setting them when the piston was at top dead center without going down 1/4 inch. (I got that from a youtube video.) And I tried the way that worked. And the clearances were WAY different in each case! It's not like you can use one method the same as the other. Oh, one other thing the mechanic told me to do- put some blue loctite on the the studs. They take a ten mm wrench. ALSO, you need a t20 torx bit to loosen and tighten the set screws.