Stalling when accel pressed, why?

[pepe]

First the facts:
1. When i try to rev up the engine it immediately stalls and quits.
2. if the choke is on, it will rev up only if i do it slowly.
3. with the choke on, and rev-ed up slowly, it reaches a limit as to how fast it runs, and then stalls and quits unless i back off on the accel. Sometimes it backfires when the high speed is reached.
4. The timing strobe shows a loss of spark every 3 seconds or so, causing the engine to cough intermittently.
5. The engine idles fine, set to 6 deg BTDC for ignition, and the idle mixture screw has been set.
6. I have a new, weber 34 ICH carb and new distributor (gap set @ .014), new plugs.
7. I rebuilt the engine, so it never has run well since rebuild.

Why does it idle well (periodic coughs), but stalls at quick accel pressing and high speed?

can't seem to isolate whether this is an electrical or fuel problem.

Any advice greatly appreciated.
-Erik

[gudjeon]

Sounds like a fuel prob to me. Try looking down the throat of the carb when not running. Pull the throttle to wide open and see if the accelerator pump pushes a small squirt of fuel out. Lacking this can cause a major "dead" spot on your throttle. Alternatively, it might be the main jet circuit of the carb is plugged up as well. I would dismantle the carb and make sure all jets are clear. It doesn't take much to foul up a jet in there.

Hope this can help,

Jon

[pepe]

1. i get a solid squirt when pressing on the accel.
2. i took out the main jet and it looks mint.
3. i took the top off the carb and looked at the two orifices and pump check valve. all clear.

how do i clear out the main jet circuit?

thanks for your help.

[rovertek]

try advancing your timing (nothing runs on the factory setting) good that is.....