F134 Hesitates - Timing Problem Or Something Else...?

1956 CJ5, F-134, 6 volt system...

Getting the CJ5 ready for the road and have what I think might be a timing issue, but I cannot dial it in...

Jeep starts and idles well, but hesitates, stutters and dies as I accelerate up through 2nd gear and higher rpms, whether driving or sitting in neutral in the driveway.

what I've done so far:
Fuel pump professionally rebuilt (Midwest Military rebuild) - dual action all metal pump
YF carb professionally rebuilt (by CMC in New Smyrna Beach FL)
new points gapped at .020 on high portion of the cam per manual - NAPA
new plugs and wires (plugs gapped at .030 per manual)
new condenser - NAPA
new dist cap - NAPA
new coil - NAPA
new fuel filter - NAPA

no vacuum leaks that I can find by spraying carb cleaner or starter fluid around base of carb, along the pcv valve and vacuum lines around the fuel pump. even clamped off the vacuum line from the wiper motor to make sure the leak wasn't there.

Hooked up a timing light and the pulley mark (chalk I applied to the notch on pulley) shows up just before the timing marker on the front of the block (5 degrees before TDC?). rotated the distributor both ways to try to fine tune the timing and it didn't matter which way I went, the problem persists. even when I get the pully mark completely obscured by the engine mark/pointer she hesitates or stutters upon acceleration.

fuel is red in color - not sure if that's "stabile" from the PO or the tank red liner that the PO applied leaching off and coloring the gas.

run the jeep from a fresh/clean fuel source and had the same hesitation/sputtering issues.

I'm stumped - any thoughts are appreciated!

 

New and rebuilt items are always the first thing to suspect. Any one of those components could be bad. So much easier if only one thing at a time is replaced.

I just had a '34 Ford distributor set up and bench-tested by one of the best experts in the country. It was worthless back on the car. Caused me huge grief.

Will your engine run smooth at higher rpm after the stumble during acceleration? If so, accelerator pump circuit may be a likely cause. Often the check valve ball gets lost during a rebuild.

 

Thanks Pete - The hesitation was happening before all the rebuilds/replacements as well. I put the items on one at a time and the hesitation continued throughout the process. Started with the fuel pump, then the carb, and so forth.

Fuel pump was leaking into the block - so that was the first thing I focused on.

If a vacuum leak, where should I re-check first. I've sprayed fluid everywhere looking for a reaction.

 

Real common vacuum leak is the carb base gasket, especially if the carb ears are bent from overtorquing.

Restricted fuel line?
Have you checked the fuel pump output at the carb? Both volume AND pressure?

 

You've set your points - but do they "hold" the setting? Excess side play in the distributor shaft can cause weirdness. A dwell meter also will show if the gap 'wanders.'

 

good points - all. A buddy is coming over on Friday with a dwell meter to check that. Will check fuel volume and pressure when I get back into town from a work trip. Sprayed the heck out of the carb base looking for vac leak, but will do everything again. Also going to pay more attention the fuel quality and line condition too.

 

Try running with the gas cap off. Might be a venting problem.