the ignition timing set wronge. BAd accelerator pump in the carburetor
Depends on the engine and carb set-up as well as the weight of the drivers foot on the accelerator. I have a 1973 F 250 with a 460 and a Holley 650 carb and I get right about 7 MPG. I can get as little as 4 MPG if I drive it like it wants to be driven. Definitely NOT the vehicle to be driving around in for fun!
The timing is set incorrectly. Carburetor(s) needs rebuilding (bad accelerator pump). Firing order is mixed up. Replace or adjust ignition points and condenser.
Accelerator cable? No. Accelerator pedal set up? Yes.Looks like 2 bolts to remove the pedal clusterfrom the floorpan and then there is a bolt going through the pivot for the gas pedal.
The idle is set too high, the accelerator linkage is sticking, or your foot is on the accelerator. Most likely one of the first two.
Cruise control
Probably start out at the manufacturers spec and increase a little at a time until best performance is achieved. The 600 should be fine for a mild 350, but a cam with that much duration will need an aftermarket convertor for an automatic. A four speed should work ok.
I can only think of a couple possibilities; You may have a faulty fuel pump or your fuel injectors could be clogged. I would try the fuel pump first seeing that it is much cheeper than a set of injectors. One other thing you could do is check the accelerator swith to see if there is enough tension.
Idle set too high or accelerator is sticking and needs lubrication.
how do you set injector pump timing for a Nissan cab star? provide a diagram.
retarder increases time to set, accelerator decreases setting time
Maintains set speed for cruising without having to step on accelerator.