My old girl is a 85 F150 with a 4sp manuel. She started life with a I6 which was swaped before I got ahold of her. Her tired 302 was drinking a quart of oil per 5 gallons of fuel so out she went.

I have replaced the old engine with one from a ~94 F150 with all the accessories intact in order to keep the serpentine belt setup (factory headers are awesome). New parts list includes;
~1975 2bbl intake (used but spotless inside)
distributer (steel gear), cap, rotor, wires, plugs, coil, "blue brain box"
2150 carb with a dorman stove kit to heat the choke. (This system works great, glad I did not delete it and go manual like the old engine.)
Electric fuel pump setup with 6psi pressure at the carb
850 cca battery
muffler and pipes
clutch system (master and slave + clutch kit)

My issue is a bog coming off idle to about 1200 rpm. Once she passes this point she runs great to 3500 rpm. Any suggestions would be greatly appreciated.

 

look for excessive slack in the accelerator pump linkage. Could also be a timing advance issue. What did you set the initial timing at ? Should be around 10-14* BTC.

 

Timing is a guess. It is set at the most advance it will start with while warm. If I drop it it seems to suffer in power. I backed the carb adjustment screws back 3/4 of a turn and the bog is almost gone and running much better. Still a stumble through. Even with the issues I seen 16 to18 mpg. Very happy with the new setup just need to get her tuned. I will check the accelerator pump tomorrow when I have light. Thank you for your assistance.

 

What screws did you adjust ? None of them will fix an off idle bog. The mixture screws only adjust the idle mixture. The idle speed screw (on the throttle lever) adjusts the idle speed. Open it far enough and you put the carb out of the idle circuit. To fix an off idle bog, you either need to add timing or remove the slack in the accelerator pump linkage (or both) Sometimes in severe cases you'd need to change the accelerator pump nozzles or the accelerator pump cam, depending on how it's expected to perform off the line. In normal street driving, that shouldn't be necessary

 

And you should set the initial timing before doing any carb adjustments. Also check to see that the vacuum advance is functioning. Pull the distributor cap, then disconnect the vacuum hose the distributor, then suck on the hose and watch to see if the breaker plate in the distributor moves.