I'd really appreciate it if anyone could give me some suggestions on my problem because I've tried everything. I have a 1978 F-150. I just got a remanufactured carb about a year ago and just hooked it up and never did much to it and didnt really try to get it running good. Ive started messing with it now more recently and it was flooding out really bad. Gas was pouring out of the top of the barrels of the carb. It then stopped working at all. I could pour a little gas in the top of the carb and it would run off of that and then cut off. So i figured its not getting any gas. I replaced fuel filters and that did nothing so i took the carb apart. It was bad inside. The old gas had turned to varnish and the needle valve was stuck shut. I then took the gas tank off by myself (full tank too). I cleaned the tank out and replaced a couple fuel lines that were cracked. I then cleaned the carb out really good. Its like brand new. I then put the carb back on and it once again flooded out of the top of the barrels of the carb. S i adjusted the mixture screws in the front of the carb. 3/4 of a turn out for each. (This is what a friend told me) When started up after that the gas started coming out of the vaccuum line that is right over top of the float. I checked the float and the needle valve is closing when the float raises up so i am lost. I have no idea what to try now and any help at all would be greatly appreciated.

 

u say the valve is closing, but is it closing soon enough, if its not closing untill the float is topped out it might be too high up, and needs adjusted to close with the float at a lower position. another posibility is that the float is bad and taking in gas and not floating like it should....what kind of carb are you working on...BTW, adjusting the mixture screws has nothing to do with the carb overflowing, thats all in the float and needle valve...that valve might be closing but not sealing good enough as well.....

 

I say pull it, rebuild it (with a new kit) and make sure the float is dead on. I say the problem is with the needle, or there is massive debris in your idle circuit.

 

The float is working so would it be ok for me to bend the ledge that extends off the end of the float that the needle valve hangs on. Would that make it close sooner or is there something else wrong?

 

on some OEM holleys that is the only way to adjust the float, if your carb has a float adjustment screw you shouldnt have to bend it, but it wont hurt to try.....be carefull cause a little bend goes a long way.....when i am adjusting a float like that i will blow into the fuel inlet and move the float to see where its at when the needle is closed, this will also let you know if its closing at all, on a non adjustable OEM holley, you have to block off the rear fuel feed for this to work though,otherwise the air will just blow out that way, some other carbs might be similar.....

 

if i bend the needle valve down can i bend it too much? should the float be level when it is closed off? what position should the float be in?

 

i would say level is a good start, by the way, what kind of carb are you working on???

 

its a motorcraft but im not sure of the model. whatever is stock for 1978 f-150.

 

my 76 F-150 460 had a 4bbl motorcraft, my 78 F-250 351m had a 2bbl motorcraft, i fought both of those carbs up and down, rebuilt the 4bbl twice and the 2bbl once, and still had issues with both, put a 780cfm holley on the 460 3 years ago, and put a 500cfm holley 2bbl on the 351m last year,it gave me a large power increase and better mpg as well.... i havent had any issues with either, well i rebuilt the 780 once because the truck sat and the gaskets dried out, but other than that i set the floats once and no problems since, BTW, most holleys you can adjust the float without tearing down the carb........i do it while its still on the motor and the engine running, but ive been working on them for years, i DO NOT suggest to anyone to work on your carb with the engine running, IT CAN OVERFLOW AND START AN ENGINE FIRE!!!!!.....ALWAYS use common sense when doing carb work....