I put a manual choke on my truck and it works fine. My question is, I thought once the engine was at operating temp I would have the choke wide open but it runs best with it closed a bit. Is this normal?

 

Not normal. It's reducing the amount of air entering in the carb. Since it still runs great I suspect air is getting in through vacuum leaks. But, If it runs good, I'd leave it alone. You do know that choke plate is adjustable???

 

i just adjusted the lever so that a full in **** is wide open, that what you mean?

 

You have a **** on the dash? If so, that would be an aftermarket addition.
I guess it's time you state what year and model truck and engine you have.

 

its a 1982 f250 with the I6. the reason i put a manual choke on is because the hot air tube going into the original choke was cut and pinched off and the rest of the hoses that went to the exhaust manifold were missing. Thought a manual choke would be an easier than going to a junkyard to find all the parts to restore the hot air choke it came with.

 

OK good, we're on the same page.
Unless youre in cold climate you probably won't need the hot air tube.
I go back to what I said before....you setting the plate closed somewhat when warmed up tells me there could be vacuum leaks allowing extra air into the manifold. Its running lean because of the extra air. Your closing of the choke plate somewhat enriches the mixture. It's not a big deal as long as it starts and runs ok.

 

ok, i've pulled every vacume line off and plugged it and still can't get it to idle smoothe with wide open choke. Where else could it be leaking? The carb is screwed together tight and mounted to the manifold tight.

 

Have you tried adjusting the Idle Mixture screw located low on the carb on the passenger front corner? Oops I dont think you have the standard YF carb, so I dont know where that screw would be, but it should be low near the mount. Other than that, if it runs fine on the open road, I guess I'd say the carb should be rebuilt.

 

just rebuilt the carb trying to solve this problem. i adjusted the idle mixture screw but seems i have to turn it out farther than i should to get the mix close. maybe i just need to buy a new carb

 

Have you put a vacuum gauge on it? Compression test?

 

So long as adjustment doesn't fall out. The later carbs have finer threads on the mixture adjustments also.

 

Do you have a leak between the intake manifold & the head? Or at your brake booster?
Aerosol carb cleaner might show it up, at an idle.

 

found the problem! Leak at the EGR valve. put a plate in it to seal it off for now. Bad news, discovered the fittings in the carb where the brass connection goes that the fuel filter screws into ar slightly stripped. (got to love previous owners). Temporary fix is epoxy. Assuming I will have to get a whole new carb???

 

You should be able to find a universal Choke Stove Kit,(Dorman 03840) in the Help! section of most auto parts stores. This simple, cheap kit (about $20) is designed to bypass the choke stove chamber on the exhaust manifold and replace the stock choke tubes completely. The kit comes with a length of coiled up aluminum tubing that you can easily bend by hand, the tubing insulation, the hardware to mount the tube to the choke cap, and a little "dome" with a hole in one end for the tubing to push into. This dome clamps to the exhaust manifold or header pipe with a simple hose clamp to trap the hot air when the engine is running and routes the hot air up to the choke cap:


The stock thermostatic "hot air" chokes with the factory electric assist works MUCH BETTER than a manual choke AND the fully electric chokes found on all aftermarket carburetors in that the choke opening corresponds with the engine temperature. As a result, the engine automatically gets the right amount of choke it needs, and because it uses hot air generated from the engine, it doesn't choke the engine when it isn't needed.

Unless you like to sit there and feather the gas on a cold engine until it warms up, a carbureted engine absolutely needs a working choke. That is why a carbureted engine will stall when the engine is cold and the choke is not working properly. Even if it is 100 degrees outside, the inside of the engine is going to be much colder than that, and normal operating temperature is in the 190 - 210 range. With the choke in place and working correctly, a carbureted engine should start right up and continue running (without your foot on the gas) without stalling in any weather condition!

 

Ahhh, the choke plate still works perfectly via the thermostatic spring, even without the hot air portion. Ask me.....31 years experience!!