Hey folks, i just bought a 79 f150 4x4 with the 400 in it. The previous owner put a 4 barrel Demon carb on it off of a larger engine and a new weiand intake.

So, the truck cranks just fine, idles pretty good but has the occasional back fire (not to bad tho). when i drive it and get up to around 1800-2000 rpms, it starts sputtering and choking out. then ill let off the gas, itll clear itself out, run good for a few more seconds then back to it again.

wanted to know what yall think about all that?

 

sounds EXACTLY like my 68 Tbird when the carb took a **** on me...i put a new carb on it and it runs beautiful now

 

It sounds like the float is set to low or the pump is not putting out enough pressure to keep the bowl full. A co-worker of mine just bought a Holley 2brl new for less than what all the big name auto parts store wanted for a reman with less warranty. Oh yeah, he got it from Summit.

 

Ok...So, what carb should i go with? what cfm for my 400? 2v or 4v?

 

well no 400 ever came with a factory 4 barrel carb...id put a 2 barrel intake and carb back on it...thats what the motor was designed for

 

I have to agree and say the 2 barrel would be better for it, but i would say buy a new holley for it and try that!

 

You could probably put the intake carb setup for sale or trade and go back to stock.