Motor idles ok. I adjusted the idle mixture screws for
max vacuum. While sitting idling, if I slowly rev it will run fine. When I give a quick burst of acceleration though, it bogs down and will sometimes backfire through the carb. When I look in the carb, it is giving a shot of fuel in both barrels, but it does sort of drip afterwards. More drip than atomized spray of fuel. The choke seems to be functioning properly. However, and this is probably an unrelated secondary issue... the kick down rod has flipped backward a couple times sticking in wide open throttle position. Talk about scary! All of this tuning is being done in the driveway in park as I’m not on the road with it yet.

I’m guessing accelerator pump, but would
love feeback before I tear into the carb.

 

Yes accelerator pump is the likely cause. Consider doing a carb disassembly, new float and carb kit and then precisely do EVERY adjustment outlined in the instructions...you will like the results.

Stuck throttle...scary...experienced it in a '67 Cougar Hi-Po 289. Had to shut it down brakes were overheating. Went and got cleaned up and then cleaned and fixed the car.

Good luck!!!

 

In my experience, the 2GC is very sensitive to float level, and the few that I've owned all needed the accelerator pump adjusted to get rid of that bog.

 

Here's another vote for the accelerator pump, but it's probably best to do a complete re-build. After you get everything right it'll work right. Be sure that ball in the bottom of the well seals properly.

 

Another vote for float and/or accelerator pump issue

 

My 71 hesitated since new. I recently drilled out the idle tubes, I think about ,002". Those carbs were not calibrated for our 10% ethanol fuel that we use today and even back in the day, they were barely tolerable. That drilling is not a job for the squeamish. Presto, no more hesitation except for maybe if you just trounce on the pedal from a stop. Cold starts are way better too. I bought the long bits and pin vise from McMaster Carr. Cheers.

 

Quite often a backfire on major acceleration is a starving engine from acceleration pump not doing it's job. Could be other things but my bet is on the acceleration pump especially if the pump is not designed for ethanol fuel...... Tedd

 

Finally got a chance to open the carb up this evening. It was indeed the accelerator pump. The pump itself was fine. It was the check ball in the accelerator pump that was the issue. Apparently it made its way out from under the pump return spring and had clogged the passageway into the main discharge. Put the ball back in its place and made sure the spring was centered in the bore and centered on the pump. The center screw in the Venturi cluster wasn’t tight enough either causing loss of pressure back toward the float bowl. All back
together now and working as it should.