Off idle hesitation
 

I'm having a drivability issue with my 72 D100. 318 2bbl, fresh carb, and ignition. When I step on the gas, I get a hesitation before the truck goes. This happens when I first start out, and when I step on the gas on the road. It doesn't always do it tho...which has me puzzled. My Duster also did it, but has a very different combination ( 340/727/Holley 4bbl ) I was thinking it was an accelerator pump problem, or a distributor advance issue...

Any ideas?

j

Does it do it only from a complete stop or even while you are moving (as in coasting but not on the gas)? What have you changed if anything since the problem accurd?

I would think that you have a problem with your timing advance but I could be wrong.

sounds more like a accelerator pump issue
have you double checked everything on the distributor though?

I agree on the accelerator pump most likely culprit. And it's just a personal bias, but I hate that 2bbl carb, I've never had one work right for me. Guess it's probably just that a 4 bbl has more flow to forgive my mistakes

dont forget the possibility of a power valve being set for the wrong vaccum. my fifth ave had a problem like that but the accelerator pump was fine and found out it was the power valve. i noticed that my car did have a lot more bottom end torque with the 2bbl i used to have on it though.

Thanks for the replies folks. The hesitation happens off idle, like at a red light, or crusing down the highway and I step on it to either catch up with traffic, or go to pass someone. Problem is, it doesn't always do it. I want to switch over to a 4bbl, but want to make sure the gremlins are out of the picture first.

j

Swapping to a 4 barrel will probably help it out, as long as the carb is set up right, your timing is dead on balls accurate, and you have no vacuum leaks.

Had the same issue with our 1970 383 Power Wagon. While changing the water pump I thought it was a good idea to check the timing chain. Often "while you are in there" works. The original nylon gears were almost gone and the slop was about 3/4". For 70 bucks I now know the factory timing setup is gone and I will not have to concern myself with that again.

BTW the truck wears the factory paint, almost no rust from AZ and 86k miles.

its a lean idle circuit.