Swapped a crusty old carb for a rebuilt one on my '78 F-150 last weekend

Went from stumbling and stalling at every stoplight to idling smooth as butter just by putting in a remanufactured Holly 4-barrel I got off RockAuto, and I'm wondering if anyone else has had that big a jump in performance just from swapping one part.

3 comments

3 Comments

johnson.adam1mo ago

That "stumbling and stalling at every stoplight" line hit home man. I had a '78 F-150 with a 351M that did the exact same thing, ended up chasing vacuum leaks for months before I finally just chunked the old Motorcraft 2-barrel in the trash and put a Holley 4150 on it. That smooth idle change is the first thing you notice but wait till you feel it under load, mine stopped hesitating when I'd punch it merging onto the highway and actually pulled hard all the way through the gears instead of falling on its face at 3500 rpm.

spencer_wood1mo ago

Man that Holley swap was a game changer for me too, but I gotta confess I went through three of them before I realized I'd hooked up the vacuum advance wrong the whole time. Nothing like chasing your tail for two weekends only to find out the problem was between the steering wheel and the seat. That stumble under load is brutal on the old Ford stuff, especially when you're trying to merge onto a busy highway and the thing feels like it's gonna stall out. I swear my 302 coughed so bad once I thought I'd thrown a rod, turned out it was just a clogged idle circuit in the carb. You ever mess with the secondary metering plate on those 4150s, or did you leave it stock?

jade4727d ago

That's funny you mention the vacuum advance, I read somewhere that some guys actually end up buying a whole new distributor before they figure out the vacuum line routing is wrong. Your 302 coughing that bad must have been scary, glad it was just the idle circuit.