I recently pulled a bad 302 out of my 77 ford and replaced it with a good 302 motor. I took the original 2 barrel motorcraft carburetor off of the old motor, put a carburetor kit in it, and installed it on this new motor. I tried running the motor but it ran rough and is definately getting too much fuel. It runs much better at higher rpm's but as soon as you let off the throttle it will kill itself. I tried adjusting the timing but this made little difference and I have good voltage at the coil. After it dies I will have to put the throttle all the way to the floor to shut the fuel off to get it started again. I am also getting gas in the oil. My question is what in the carburetor might be causing this? Thanks!

 

is the fuel flowing right up out of the bowl vents? mine just did this and something was in the needle/seat. take the top of the carb off, pull the float/needle. crank the motor(fuel will shoot up out of the seat) to clean it out. make sure the needle is okay. and put back together takes five minutes if all is well.

if its been sucking down that much fuel it probably just got past the rings. make sure the carb is okay and the fuel pump(when the diaphragm goes bad it can push gas into the crankcase) too and go from there

 

Stuck/sunk float
Needle not seating
Punctured accelerator pump diaphram
Initial carb settings are waaaaaay off.

... you didn't happen to invert the carb after its rebuild, did ya??

 

It can be pretty easy to put the retainer clip for the float in wrong but you would have fuel running into the carb all the time like a float needle stuck if that was it. Fuel pump like stated above..