My 77 F-150 w/ 351M and 2 bbl carb used to get great gas mileage. A while back, the mechanic decided the carb needed rebuilt. Since the rebuild, the mileage has only been half what it used to be or worse and I don't see any increase in performance. Perhaps a decrease. (I'm not sure of the numbers in gas mileage because my father owned the truck before me and I've only had it since it's been getting crappy gas mileage.)

I think the last time I checked the gas mileage, I was only getting 6-7 miles per gallon.

Is something just messed up in my carburetor or could something else be the problem. I've also been thinking about upgrading to a 4bbl carb and I've heard that if you're not running it hard, you actually get better mileage with a 4 bbl than a 2.

Any ideas will be appreciated.

 

i replaced my 2 barrel setup with an edelbrock intake and carb...at first, i used a motorcraft carb (spreadbore) with an adapter, then switched to an edelbrock squarebore because i couldn't stay out of it long enough to take advantage of the ford carb's better mileage....

 

Maybe your float level is too high. Does it emit any black smoke.

1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything

 

No smoke. Actually to drive, look at, or listen to the truck, you'd think everything was working perfectly. It just gets terrible gas mileage since the carb rebuild.

 

I had the same problem with my 78 f100 with a 302. I went ahead and put a edelbrock intake (4 barrell) and a Edelbrock 600 carb. The 600 should be more than enough for the 351 and if you dont keep your foot in it, you will get muck better gas mileage.(The problem for me is not puttin it to the floor!) Hope this helps.


P.S. Summit has the cheapest Edelbrock Intakes that I've found

 

 

Thanks. It sounds like that's what I'll be doing.