Stumble

I just installed my new solex yesterday and although it starts and idles good it stumbles and sputters when i give it gas. Im guessing a fuel delivery problem but where??? Do i need to check the float level, could it have changed during shipping. I know its not in the igniton because its all new. Any insight??????

 

I would suggest checking the accelerator pump in the carb. Look down into the carb as you activate the throttle linkage (engine not running). You should see a good "squirt" of fuel into the venturis. If not, then the accelerator pump is bad. (it may be torn).

Otherwise, I'd check the timing. You say the ignition is all new, but the timing being "off" could possibly cause a stumble, too.

If you're still running points, check the dwell too.

I hope this helps -

 

I recently installed a Solex on an M38A1. I agree with Gixx's suggestions above.

If the problems you are describing occur only just off idle, it may be improper throttle plate position caused by improper adjustment of the idle speed screw (not to be confused withthe idle air/fuel mixture screw)

I cannot 100% guarantee the Solex uses an "off-idle slot" (as I did not have the problem you describe, and didn't look) but most vehicle carburators (old spelling), use these to compensate for the brief period off idle before the accelerator pump and/or main jet kicks in. (the power valve, if used, is usually ported below the throttle plate, and will not richen the air/fuel mixture quickly enough to compensate for the sudden drop in vacuum caused by off-idle condition)

If it has an off-idle port, it is usually a 2-3 mm long port (vertical) located near the idle air/fuel mixture port. (look for a small dash next to a dot) just at the edge of the throttle plate when fully closed.

The edge of the throttle plate should be located about 1/2 way up the port (approximately). if the throttle plate is positioned too far down (or below) or too high (or above) the off-idle port, then you will have a stumbling problem until the accelerator pump kicks in.

This misadjustment is usually caused by trying to increase or decrease idle speed to correct specifications when the timing is too far advanced or retarded, or there are vacuum leaks.

I would first re-verify everything Gixx suggested. Re-checking is a nuisance, but required for proper troubleshooting.

If there is still a problem, check the position of the throttle plate.

 

I had a solex carb with a stumble. Timing needs to be checked. Getting a Pertronix helped a lot, if not then like previous post dwell has to be dead on and the final thing is carb mixture. I'm still playing with it and each time it gets less and less.

It's just a Jeep thing.

 

I have a Solex as well, and get a slight stumble off the line when the engine is still "cold". That is the temp gauge is reading "normal" temp, but that temp hasn't fully reached all areas of the engine. IIRC, Billy and others have said to only adjust the carb settings with the engine fully warm. That's what I did, runs just fine (No stumble) when fully warm, just this minor glitch when cold. Even then, it's more my fault for not using the skinny stick a bit more smoothly for the first few miles....

YMMV

 

I had to adjust the accel pump setting some and mine is fine , no stumble at all with points . My timing is a little off but no stumble,Steve knows