Hi to all; I own, operate and fix an 87 F150 with the "H" code 351W complete with Holley 4180 carb.

First off, does anyone know what the CFM rating is for this carb?

Second, can you folks recommend a good replacement? I'm not badmouthing Holley, I've known their name since I could spell t-r-u-c-k, but my research, mostly word of mouth, leads me to believe that the Holley carbs are best left for racing and not street duty. It starts and runs well, when you're on the gas. It dosn't seem to want to idle smoothly and when it does, it will not for very long.

Most other causes of a poor idle have been eliminated and this carb, as far as I know, is the original unit; it's been rebuilt twice while I've had it.

I'm thinking this motor would probably not need more than 500 CFM, based on the formulas I found:
CFM = CID X (max or target RPM) / 3456

I then took 80% of the result, (covering for typical 80% VE of a stock street motor), and came up with about 463.

I'm not looking to win any races, this is a daily commuter vehicle; a smooth, consistent idle is my primary goal, with better mileage being a plus and I like having the other two barrels there, just for security ;-)

Thanks in advance.

 

Carter makes a very good and reliable carburator, for about the same price as a replacement holly. Your carb should be a 600cfm holly with vacume secondaries. The carter has slightly smaller primaries and are jetted accordingly, the escondaries are slightly larger than the holly, this should help with the mpg and performance.