I have a 73 F250 2WD Camper Special with a 460/C6. Its a factory Motorcraft 4bbl carb. Im having what I belive to be some fuel/carb issues. This truck sat for a number of years before I got it. I cleaned the tank and installed a new mech fuel pump. I did a full tune up inc cap rotor wires plugs points and condenser. It has both the canister filter on the pump and an inline filter before the carb. I can see the gas is very clean and free of debris.

The symptoms:
Its starts right up hot or cold. However the idle is very poor. It has no power when you jam the accelorator. Now it is running very rich. Fouling plugs and black smoke and running in all speeds poorly. I disconnected the choke all together since it hasnt been below 105 degrees here for months.

I replaced the carb with a rebuilt Edelbrock 650 performer carb w a manual choke, hoping to improve idle. It had alot of the same issues but the idle was a little better. I set the idle mix screws all the way in then backed them out 2 1/2 turns. Yesterday I pulled it around to the house after running it for a few minutes and it stalled. Similar sound to running out of gas. As I feathered the throttle it bogged down instead of going up in RPM.

I tried to start it again w no luck. I eventually flooded it like a dumba**. I pulled the plugs they were all soaked w gas and covered w black soot. I cleaned the plugs let it sit overnight and it started up the next morning.

Now the idle was awful. It would run for a few minutes and conk out. While it was running I reved it up i could see raw fuel spitting out of the top of the carb. I pulled the top end off the carb and verified float bowls were not stuck. I cleaned the venturi and metering rods while I was there. Reassembled. It was better. Took it for a drive. As it heated up it got worse and worse. Belching out black smoke and eventually unable to run.

I broke down on a back street and swapped the old original carb back on. As I disconnected the fuel ine a ton of fuel came sraying out of both lines. Ive never seen that much come from a Mechanical pump. But I suppose I could be mistaken. I was wondering if that was my problem. Too much fuel incoming.

As I went home w the other carb on it ran better but still was not making the power a 460 should. I sprayed around the intake and carb w starting fluid to see if I had any vacume leaks. I had a bit of an intermit one at the hard lines that come from the intake manifold that hook to the choke. Can I pull that plate and block it off w a solid one?

 

Im pretty sure these trucks never had the Autolite 4100 or 4300 4 barrel installed on them.

Its probably a Holley carb you have unless somebody put the Autolite on it.

Did you buy the rebuilt Edelbrock from Edelbrock? If so im surprised it is doing the exact samething as your other carb. Maybe something weird going on with fuel pump and building to much pressure?

Other things I can think of are float level is to high or dirt keeping needle from seating good. Have you made sure choke is staying open?

 

Yeah its def a Motorcraft 4300 looking thing. The edelbrock I got from a friend and I heard it run on a 460/C6 combo in an rv...Im gonna double check float level and seat conditions. Ive never used a fuel pressure regulator on a mechanical pump...I had thought about doing it now.

 

I tore down the carb today and verified the floats/seats are good. One thing did jump out at me. This truck should have a resisitor wire ..bolted to the drivers side valve cover is a ceramic ballast resitor.It looks very chrysler-ish. Its an obvious add on. I wonder if that is reducing my voltage too low giving me a weak spark..thereby a rich condition. How much reisitance in OHMS should a stock res. wire have?

 

The ballast (resistor wire) should be 1.3 to 1.4 ohms. This creates a resistor divider with the primary winding of the factory coil, which is generally 1.0 to 1.5 ohms. This drops the primary voltage at the coil to 7 to 9 volts, depending on a variety of factors.

A vacuum gauge is the best tool for diagnosing carburetor problems, IMO. Without it, you're taking shots in the dark. You can't measure length without a ruler, right?