Engine Stutters real bad

Ed88

Member
Aug 21, 2017
65
12
18
So I got the fuel pump changed out on my 74 mach1 finally got it started up and it idles fine. When to take it around the block and at first was fine then started stuttering and bucking really bad. I pulled over let it level out and then it was fine for a like 20-30 yards then started falling on itself again and bucking hard.
It has a rebuilt carburetor on it but not sure if it need adjustment or anything. Honestly this is the first as t carbed car I've owned and I'm at a loss of what it could be. Has new coil, plugs and wires on it.
Any help would be great I really would like to have it going.
Thanks
Eddie
 
  • Sponsors (?)


Carbs are a pain in the rear. Describe the stuttering and bucking a bit more - was this at cruise? Or when accelerating or decelerating?
Verify the function of the electric choke first - make sure it's fully warm and the choke plate is completely open. Make sure the carb's fastened reasonably tight to the manifold and that you don't have any huge vacuum leaks.

Sounds to me like maybe you drove off when it was still cold, and when the choke fully opened, the car was running too lean. (If the stumbling was at cruise rpm). It sounds to me like it isn't getting enough fuel - fuel filter maybe, or a kinked line during installation? If neither of those, it's possible the rebuilt carb was just one of those eBay Mexican 2100 clones which are terribly jetted out of the box. I had to significantly enlarge the jets on the one I bought (they weren't Holley-style jets so finding different ones was a pain so I just drilled 'em out).

Anyways, if it's idling good, everything else is mechanically sound (timing, etc.) and it's not during acceleration (but at cruise) it's quite possibly a main jetting issue - and you'd have to sort out the jets and install some replacements. Unfortunately it's not an easy adjustment - only the idle mixture is easily adjustable, everything else (power valve, accelerator pump, main jets) requires parts to adjust. Carbs are a pain in the rear. :)
 
Well I let it warm up pretty good before I took it down the road. Going down my street it was perfect. Turn the corner, start accelerating and suddenly it stutters bad all the way around the block to the driveway. Second time it was good until I turn back on my street and was cruising down the street and it started doing it. The carb is a Canadian rebuild from rockauto. I replaced the rubber up front going to the pump and also from the pump to carb.

Eddie