Tuning carburetors

I have a problem. I have never really known how to properly tune a carb. This is now biting me in the butt with my daily driver (66 Dodge D100 318la with a 2 barrel). I did a search and I really haven't found anything relevant. The problem I am having is I have a dead spot off idle and the prior owner had installed a fuel pressure regulator with the stock fuel pump. If the regulator is cranked there is no dead spot but the truck loads up and dies if I'm sitting. So my real question is how do I tune a carb? If there are any resources to properly learn or any advice I would really appreciate the help.

 

Sounds as though your accelerator pump is either not working or is not pumping enough fuel into the intake when you put your fott on the gas pedal.
One question to ask is does it do the same thing if you softly accerate aay? If it does not then its a certain bet that the acceraltor pump is faulty
A standard carb rebuild kit will have a new diapharm and return spring in it and should be replaced as a matter of course when you install the rebuild kit. hey are still readily available either at your local parts store or on flebay.

Other possibilities are intake leaks or a loose carby - anything that creates a lean mixture right at the time when you need a n extra squirt of gas.

 

Sounds like the needle and seat aren't stopping fuel flow under full fuel pump pressure. Somebody might have set the float lower to try to get more pressure on the needle valve. A carb rebuild would be a good idea. Check the float to see if it is in good shape. Foam floats can absorb gas, especially with the alcohol gas. A brass float can also corrode from alcohol.

If you rebuild it yourself, use the diagrams to get it assembled correctly and the most important thing is to follow the instructions to make all of the adjustments.

 

First, chuck the pressure reg., no need for it on a stocker. Second, replace the needle and seat, that's why the PO put in the reg. And check the float for a crude resolder job, it might be too heavy to work right. Third, a stumble off idle can be caused by not enough spark advance, though it doesn't sound like it in this case, since it goes away with more fuel pressure.

 

Pope has got your culprit, and a theory to explain it.

 

Snap pictures of the dis-assembly proccess with your cell phone or camera if your unsure about rebuilding it... That way, you can go back to those pictures and see how everything goes back together.. Piece of cake!