This may be related to another topic I have posted or maybe not? I just installed a manual choke kit on my 84' f-250 351w 2bbl carb and not sure if it is working right? The automatic choke didn't work at all, i tried everything so I bought a cable kit style manual choke and installed it to specs. It manualy opens and closes the choke just fine but when starting the engine it does not make it rev up like a choke is suppose to do. What happens is when the choke is fully closed I pump the gas a couple of times and it will fire up but have to open the choke fully or the engine will stall. Even at half way the engine will run but not rev up. Once the engine gets warm it will rev up a bit only when the choke is left open about 1/4 inch position and die out when fully on. Then will rev down when I open it fully. I'm thinking that the idle speed might be too slow or there is another divice that works with the carb that is not allowing it to rev like it is suppose to. Or, maybe that is the way these carbs work? Any advice?

Randy

 

Behind the round black choke housing there are some linkages and a cam. If you move the throttle on the driver's side, you should be able to see some linkage move on the passenger side behind and below the choke housing, and if you can figure it out, that's what holds the throttle open for a fast idle. If it has been disassembled, I will be the first to admit it can be hard to get it back so it works correctly.

If you get the fast idle working, you should be able to pull the choke fully closed when it's cold(while pushing the pedal to the floor) and the choke door will shut fully closed. Then when you start it, there should be a round diaphragm thing with a lever that is actuated by vacuum. This is called te choke pull-off, and when the engine starts, the vacuum should build, and the lever for the choke pull-off should crack the fully closed choke door open a little bit so it won't choke out and stall.

 

Doesn't sound like he has a choke pull off connected. Here's what a choke does and why they call it that. Place your hand over your mouth and nose and try to breathe.

When the choke is closed almost all air is shut off and it pulls extra fuel into the engine. Combustion requires fuel and air. It sounds like it's operating normally. Unless you have leaks in the fuel line (sucking air instead of fuel) or a blown power valve in the carb (which allows the fuel to evaporate when sitting), you shouldn't have to use the choke in the summer and only use it sparingly in the winter.

 

There are guys on here that say you don't need a choke at all, in any kind of weather. I will admit with the vehicles I have had through the years, they all had different "personalities" and some required more choke that others. But the engine I have now, completely stock 351w with the stock 2bbl, does need a choke in any kind of weather. On the warmest days, you could leave it off(I have manual choke too), but it's not going to start unless you pump the gas about three times, and then play with the pedal for about 20 seconds. But if I use the choke, no matter what the weather, it's push the pedal once while pulling the choke, and it starts everytime, going right into fast idle. I can then kick the pedal and bring the idle down a notch right after I start it.