This engine is on a 1984 Snapper RER. I have not been able to get it to smooth out. I have cleaned the carb very thoroughly and replaced the gasket. I have recently adjusted the valve clearances. It starts easily. But it runs like a hit and miss engine. I just put in a Chinese clone carburetor and the miss disappeared, BUT it ran way too fast. My tach recorded 4900 rpm and was slowly climbing. I tried adjusting the high speed screw but could not get it to slow down, so I shut it down. I checked the governor arm and it was properly adjusted. I put the old carb back on and the miss returned but the tach showed 3200 rpm. Did I get a defective carb? Can a carb make an engine overspeed? I thought the governor would prevent overspeeding. Could I have a bad governor? Why would it govern speed with one carb but not the other? I have cleaned a lot of carburetors but I can’t help but think I’ve missed something on this one. Is there a passage on this carb that is hard to see?
8hp flathead 190707 intermittent miss
- Thread starter Oddjob
- Start date
ILENGINE
Lawn Royalty
Have to be careful with some of the chinese aftermarket carbs on some engines because the throttle linkage in the carb is set up backwards. So the governor can think it is closing the throttle to limit speed but is actually opening the throttle.
I don’t remember if I blew it out. The openings in the jets and emulsion tube are so large that you can see light through them. But it’s obviously not getting enough fuel so there must be a blockage somewhere, but dogged if I could find it. This time I’ll soak it and blow it out. The backward governor linkage theory intrigues me. March Madness had my attention tonight but tomorrow will be carburetor day.
Cleaned it again this morning. All holes were clean but sprayed and rodded and blew them out anyway. Reinstalled and it still ran like crap, missing and popping.
The linkage is the same, more’s the pity. I was hoping that was the problem. The throttle throat curves as it connects with the manifold and I can’t figure out how to get a caliper in there for an accurate measurement. But I can get my ring finger almost all the way to the throttle plate and I think the throat on the Chinese carb is slightly larger than on the oem. Would that make the engine get too much fuel and overspeed?
I did that first thing. Just went out and did it again. Also tried bending the tab but still can’t get the rpm’s under 5000. With the oem carb the rpm’s are around 3000, so I don’t think the internal parts of the governor have failed.