Off Idle Stumble at WOT
Posted: June 20, 2026, 9:45 am
I’ve been MIA for a while, but recently decided to dust off the old truck.
The problem I’m having is if I punch the pedal to the floor at idle the truck with quickly bog down and then die. If I lightly press the throttle to gradually rev it up a bit, and then punch it to WOT, it will rev up as normal.
This is a stock ignition, stock carburetor setup on a 63 F100. 223 with autolite 1101 and the load-o-matic setup.
Here’s what I have done:
Idle is set to 550 rpm (I know the manual calls for lower, but my engine has never cared for it).
Points are at .025”, dwell is 38.
Spark plugs are autolites set to .030” (per the manual this is the gap for ‘63)
My timing mark is missing from the engine, so I set timing using a vac gauge. Vac is pulling a steady 17.
Vac gauge had a slight flutter so I checked the valve lash and set them all to .019”.
Accelerator pump was obviously a prime suspect. Rubber looks good, and the pump arm was set to 3/16”. Vent tube is also in spec.
Vac advance in the dizzy is good and holds vacuum.
Throttle shaft has no play, no vac leaks.
My next move is to replace the spark control valve on the carb.
Does anyone have any other pointers or something I may have overlooked? This problem is driving me NUTS
The problem I’m having is if I punch the pedal to the floor at idle the truck with quickly bog down and then die. If I lightly press the throttle to gradually rev it up a bit, and then punch it to WOT, it will rev up as normal.
This is a stock ignition, stock carburetor setup on a 63 F100. 223 with autolite 1101 and the load-o-matic setup.
Here’s what I have done:
Idle is set to 550 rpm (I know the manual calls for lower, but my engine has never cared for it).
Points are at .025”, dwell is 38.
Spark plugs are autolites set to .030” (per the manual this is the gap for ‘63)
My timing mark is missing from the engine, so I set timing using a vac gauge. Vac is pulling a steady 17.
Vac gauge had a slight flutter so I checked the valve lash and set them all to .019”.
Accelerator pump was obviously a prime suspect. Rubber looks good, and the pump arm was set to 3/16”. Vent tube is also in spec.
Vac advance in the dizzy is good and holds vacuum.
Throttle shaft has no play, no vac leaks.
My next move is to replace the spark control valve on the carb.
Does anyone have any other pointers or something I may have overlooked? This problem is driving me NUTS