In Reply to: Re: 8N popping/sputtering at idle posted by Ed Gooding (VA) on May 27, 2026 at 17:53:13:
Thanks for your response. In my initial post (18 May 2026) I utilized a propane torch looking for an air leak. I repeated the procedure utilizing a spray can of Gumout carburetor cleaner. I cannot find an observable air leak.
I repeated Bruch Haynes’ algorithm for the adjustment of the Marvel/Schebler carburetor. The fasted idle, not the smoothest idle was obtained with the idle mixture adjustment needle closed to 1/8-1/4 turn open (400 RPM). I feathered the choke and with the choke pulled halfway out the idle RPM dropped (interpreted as a rich mixture) but the roughness was still present. As I slowly pushed the choke in the RPM initially slightly increased and the roughness decreased but was not resolved. As I continued to push the choke in the initial roughness returned when pushed all the way in. There is no hesitation when I “jerk/yank” the throttle from 400 RPM – 1500 RPM. I can kill the engine with the choke all the way out.
Do I need to move from the carburetor to the ignition system?
Any comments would be greatly appreciated.