My 351W Bronco has a somewhat rough idle. There's no stalling at any speed including at idle. In acceleration or top speed, I notice no perceptible missing or sputtering, rather, it's smooth as silk. The idle is slightly rough when I start my cold vehicle and gets progressively rougher as the engine temperature increases. I have changed my distributor, rotor, cap, wires, and plugs. Could this be a carburetor or vacuum leak issue? My rebuilt carb is the stock 2 barrel installed 3 years ago. This roughness has been going on for 6 months with no increase or decrease in symptoms so I do not feel it's a bad tank of gas. Can anyone help here?

 

try the curb idle and fast idle, then the mixture and look for vaccum leaks. try the line that goes from the carb to the dist. with that pulled out the engine iwll run slower and rough

 

Thanks for the tips! I will try these and let you know how I make out.

 

Hi Vampiro,
I had my mechanic check out the rough idle problem. He told me that he felt the idle was as smooth as it can get for a carbureted vehicle and that I was too "****". He did check for vacuum leaks, timing, and checked the carb adjustments and found nothing wrong. Thank you for your help.

 

sounds like you need to get yourself a new mechanic. after i got my intake on i found out my dist was frozen, took it to my mechanic and he replaced it for like 75 bucks. i have no air leaks, as far as i can tell and my truck runs very smooth. having never bought a carbed vehicle new i dont know what they are like from the factory but my dad said my truck runs like our old van did when it was new, a 78 E350 with the 460 C6 and he said that was smooth.

once i saw a cadillac, i think it was a 64, all orig with about 60k miles on it for sale, when the guy started it up that engine didnt even budge. i put my hand on the valve cover and i could barely feel movement at idle.

1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil

 

I hear you on the new mechanic. If it is the carb, maybe I can live with it for a while more. I plan on throwing on a Edelbrock 1406 (and appropriate manifold). Seems to be a popular carb for the street.