304 Fuel Starvation/Stalling?

Took the CJ-6 out for a quick drive today while it's at the shop. Just had the carb rebuilt. The mechanic warned me of the fuel starvation issue, so I wanted to see for myself.

After it warmed up, it wanted to stall under load, but then I would push the clutch in, and it would come back to life. let clutch out, wants to stall, push it back in, back to life. So, with the clutch in, I started pumping it, and it would rev very freely, as well as idle smoothly. Then I went to let the clutch out (to get my a$$ out of the street!) and it wanted to stall again. Each time it wanted to stall, it would have had I not pushed the clutch back in. Well, after a few minutes of this, and pushing it off the street into parking lot, it started to move under its own power again, as if the problem had gone away and I was able to get it back to the shop.

Now, I am not handy with a wrench, especially when it comes to fuel delivery and tuning (hence the reason it's at the shop), but here are my guesses.

1) Bad fuel pump?
2) Bad fuel filter?
3) Crud in fuel lines?
4) Bad fuel lines, perhaps collapsing uder load??
5) Carb tuning?

Please chime in anyone and everyone!?!?! It's at the shop, and the guy said he would get it solved, and didn't seem too worried. I do trust him, good rep here in town. I'm just asking all the other Jeep experts out there to relate their own experience, after all, many heads are better than one!

Thanks for any help!

p.s. eventually this won't be an issue, cuz I plan on either fuel injecting the current engine, or swapping in a late model V8. Until then, I want this engine to run as reliably as possible.

 

Sounds less like fuel starvation and more like something in the drivetrain binding.
Usually fuel starvation will be consistent even with the clutch disengaged.

 

Possible, but when it first started acting up, it was while I was moving along at a decent pace, ~20-30mph, and it was rolling just fine, with no odd noises, or clunks, etc. My '73 w/304 used to do the same thing, and a new fuel filter helped, but I didn't drive it much after I changed the filter.

 

Mine had similar symptoms when I was getting the fuel system cleaned up and ready to go. I could rev it with no problems, but if I tried to put it under load it wanted to die.
Mine seemed to be a combination of things.
1) replaced my old fuel line, collapsing vacuum line the PO installed as fuel line (genius)
2) replaced my fuel filter again, lots of crap in a new one I had just installed, getting all that crap out.

What I think actually fixed it.
3) Properly adjusted the idle mixture on the carb after letting the engine warm up good.
4) After adjusting the idle mixture I then properly set the timing to about 6 deg BTDC.

Note: I have a 232 I6, she seems to be cold blooded
My timing was set too far BTDC, which would make sense why I couldn't generate any horsepower or RPM under load.

 

I'm thinking timing is advanced, just like Brieoff's. Inability to accept throttle under load is classic symptom of too much advance.

 

Thanks for all the tips! I will definitely pass them on.