318 Hesitation

[75Adventurer]

Hi All!

Well, I recently had the old 75 W100 tuned up (plugs, wires, rotor, distributor), carburator adjusted, belts replaced and a new water pump installed.

Anyway, none of this cured the hesitation that exists when the motor is cold.
Once the motor is warm, it runs beautifully. I mean beautifully!! :cheerl:
Problem is, it takes about 20-30 minutes of driving before the hesitation ceases. It generally happens when depressing the accellerator - seems to starve for fuel.

Being carburated, Is this "the nature of the beast", as it were, or is this something that can and should be remedied? Would a carburator rebuild possibly fix this?

Thanks for any input.

[Awingandachair]

Check the float level and the accelerator pump. If the float is to low or the pump is not giving a good sqirt you will have hesitation. May be just need to adjust the choke. If it's not getting enought gas all the tune up in the world want do any good.

[Speed Dragon]

Look down the throat of the carb (w/ the choke plate open) and work the gas by hand. If you don't see 2 streams of gas shoot out of the boosters (the little round cylinder things sticking out into the throat area) then the accelerator pump is bad.

If you do see good squirts of gas, then the timing is probably off and needs to be bumped up.

[volaredon]

clogged heat crossover passage in intake and heads.

(it scares me when someone says "I HAD_________ done to my truck"; I could never do that unless I lost the use of 3 of 4 limbs, being that I made my living as a professional "wrench" for 18 years. There's too much difference between what I can do that job for, vs what it costs me to "have" it done for me!
Often you can buy the tools needed for the job (or borrow the more specialized ones) cheaper than paying the shop to do it for you; and those tools will last to do that job time and again!

[dmopar74]

i came across this while looking for something else, but thought it might help, was about a 318-


Mine was a 1976, and it stumbled and sagged badly from the time it was started until it was fully warmed up It did this from the time it was new. This is a classic sign of a too lean mixture. I happened to have a friend who worked in the service department of a Dodge dealer, and he advised me to raise the metering rods about 1/16 th of an inch. This can be done without disassembling the carb. Just add the additional 1/16th inch rise, and you'll cure your problem. I did this on my car, my dad's 1976, and my uncle's 1977. Worked in every case.

[Megunticook]

Problem is, it takes about 20-30 minutes of driving before the hesitation ceases.

Just curious--next time you take it out notice where the motor temperature gauge is during the stumbling. It shouldn't take 20-30 minutes for the motor to warm up, so I'm probably wrong here, but if that's the case I would be looking very closely at the choke.

dmopar mentioned an overly-lean mixture, and I would agree that your motor sounds like it's behaving this way. If by chance the choke is not closing properly when the motor is cold, your mixture will be overly-lean and the motor will hesitate and stumble when you give it gas. Does it every actually stall?

You can check this by removing the air cleaner and looking down into the carb. when the motor is cold. The choke butterfly valve should be closed most of the way, which serves to restrict the amount of air entering the engine (which, in effect, makes the mixture richer until the motor warms up).

Good luck--I'm sure you'll get this solved.

p.s. I would have to agree that you should be very careful who you allow to work on your truck. In my experience, a lot of mechanics aren't familiar with carbs. and other aspects of older vehicles, not to mention the fact that a lot of mechanics are sloppy and rushed; tuning up a 318 is not hard to do, you should consider taking this on yourself.

[Speed Dragon]

Also, make sure the choke is adjusted properly. I usually set them to where there is slight pressure holding it closed when fully cold. When you start it, it should open about a 1/4" at least if the choke pull-off is working right.