Autolite 4300 Carburetor Troubleshooting

Do I run distributor vacuum advance from driver side of car port or on the passenger side port?

As I recall the early 4300 only had one vacuum port and its on the drivers side. if his model has more than one port, then it is still on the driver side. Have him check for vacuum at hot idle and there should be no vacuum at idle. If he has more than one port then it might be canister purge port.

I’m looking for the location of the second check ball (the smaller diameter check ball) in the main body. The larger check ball is still in the accelerator pump well. I inverted the main body during disassembly and noticed the check ball fell out but don’t know where it came from. I looked in all of the diagrams you have online but don’t see it anywhere. The part number of the carburetor is D2ZF-AA

In the injection nozzle portion. It takes the small check ball and a weight on top.

I have a ’68 Mustang with an Autolite 4300-A carb Ford PN C8ZF D It was only rebuild 5 years & 3,000 miles ago by a carb shop in Florida and I bought it last year and although it starts and cruises fine, I find it hesitates and sputters a bit on hard acceleration. Now I live in Calgary, Alberta, Canada which is 3,500 ft higher than Florida and I was wondering whether you would recommend smaller jets. If so, what size please? Also, if I’m going to take the carb off to change jets in my nice warm work shop, what gaskets should I have on hand?

3000 miles in 5 years is a very long time these days. When a vehicle sits around the ethanol will eat at the rubber parts. The hesitation is probably in the accelerator pump circuit. The rubber cup may be bad.

Hesitates or Bogs
*So when you step on the gas the engine seems to want to die but then eventually gains RPM.
Your problem will be with the electrical system, or the accelerator pump system.

Electrical problems will cause a bog but for some reason most people start with the carburetor. Check the timing to be sure it is advancing when accelerating. Weak spark plugs can also cause a problem.

Aside from electrical there is most likely a problem in the accelerator pump circuit. When accelerating the engine needs an extra squirt of gas in order to get from low speed to high speed. The pump circuit provides this extra fuel.

1st do a quick pump test.
If you see a good squirt then move on to something else, the pump circuit is probably OK.

If the squirt is weak or non existent. Look at this page which spells out how to test and adjust the pump circuit.

Updated on 12/10/2020

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