The Ford Barn

Thodge · 05-27-2024, 11:44 AM

Just rebuilt my Zenith carb because of an intermittent loping idle and loading up/stalling while stopping. It still had original Zenith jets in it and the tip of the cap jet looked like it got bent while the carb was disassembled at some point. It is an early carb that has the brass GAV seat and didn’t have a gasket under it so that was a big part of my problem, I’m sure. The float was set according to the specs in Les Andrews’ book but in an effort to control the stalling at stops, I lowered the level 1/8”. Started it up and got everything adjusted in and it made a huge improvement in lower rpm smoothness and idling. Only trouble is trying to accelerate and climb hills. You notice it just pulling out of the driveway that it just doesn’t want to rev. It feels just like a tractor with a governor on it, will run smooth all day at part throttle but when you put your foot down, there’s nothing there. Almost seems like the main jet isn’t flowing at all or very little. I compared the orifice hole sizes on the new and original jets and there’s almost no difference so I’m stumped. I also replaced the fuel line and screen in the sediment bowl at the same time so it doesn’t seem likely that it got a particle in it that could clog the jet already. Doesn’t seem likely either that lowering the float a bit would make it act like this either. I would think it would starve for fuel, then recover when you let off the throttle, then gradually starve out again. Any thoughts?

05-27-2024, 11:44 AM	#1
Thodge Senior Member Join Date: Apr 2024 Location: Northwest CT Posts: 225	Power Loss After Carb Rebuild Just rebuilt my Zenith carb because of an intermittent loping idle and loading up/stalling while stopping. It still had original Zenith jets in it and the tip of the cap jet looked like it got bent while the carb was disassembled at some point. It is an early carb that has the brass GAV seat and didn’t have a gasket under it so that was a big part of my problem, I’m sure. The float was set according to the specs in Les Andrews’ book but in an effort to control the stalling at stops, I lowered the level 1/8”. Started it up and got everything adjusted in and it made a huge improvement in lower rpm smoothness and idling. Only trouble is trying to accelerate and climb hills. You notice it just pulling out of the driveway that it just doesn’t want to rev. It feels just like a tractor with a governor on it, will run smooth all day at part throttle but when you put your foot down, there’s nothing there. Almost seems like the main jet isn’t flowing at all or very little. I compared the orifice hole sizes on the new and original jets and there’s almost no difference so I’m stumped. I also replaced the fuel line and screen in the sediment bowl at the same time so it doesn’t seem likely that it got a particle in it that could clog the jet already. Doesn’t seem likely either that lowering the float a bit would make it act like this either. I would think it would starve for fuel, then recover when you let off the throttle, then gradually starve out again. Any thoughts?