In Reply to: Re: Governor idle adjustment And timing advance posted by Tim Couch on December 09, 2024 at 21:56:59:
You may have your governor adjusted as best as it can be then. How about optimum adjustment of your carb? Bruce Haynes, a long-time contributor here, wrote this helpful how-to on adjusting the MS carb:
Make sure the tractor is at operating temperature; depending on the ambient temperature, that usually takes 10 – 15 minutes at idle.
Both Ford and Marvel/Schebler (assuming you have a M/S carb) say to set both the side-pointing idle mix and the down-pointing main jet to 1-turn as a starting point. I set the down-pointing main jet to 1-1/2 turns and do not fool with it until the final step.
Then adjust the side-pointing idle mixture for the fastest idle; not the smoothest idle. Next, adjust the behind-the-carb idle-speed setscrew for a very slow 400-rpm idle. Do that idle mix adjustment for maximum idle at least 3 times. Make sure that you turn the screws slowly, like 1/8 of a turn at a time and wait a second or two for the engine to catch up. Take your time!
Do it like this:
1. Adjust the idle mix jet until RPM increases
2. Adjust the idle-mix set screw until the engine nearly stops (as slow as you can get it unless you have a tach that tells you 400 rpm)
Repeat steps 1-2 three times.
Remember the side-pointing idle mix is out for lean, in for rich.
If you do not have any problems inside the carb, it is easy to get the idle down to 350 - 400 rpm.
Your last step is to go back to the main jet. Remember, in for lean, out for rich. If you end up turning it OUT more than ½ turn for max power (remember, you already had it 1-½ turns out) then stop right there because you have a dirty carb or a fuel problem.
Lastly, each of us has his own definition of a carb rebuild. If your rebuild did not include soaking the carb 24 hours in a bucket of caustic carb cleaner and blowing out every orifice with a rubber-tipped air gun, you didn't do a rebuild, IMHO. You just replaced parts.