Can't get engine to idle

48 cj2a, L head motor. The engine was rebuilt, plenty of oil pressure. No leaks except the rear main. 12 volt conversion with gm alternator. New solex carb with fuel pressure regulator set at 2 psi. I'm pretty sure the timing is correct, I set it before installing the engine and checked it with an adjustable timing light. The heat riser appears to be functioning properly. The crossover tub is hooked to the carb and the dipstick breather, but no the air filter. PCV is new and hooked up.

The engine doesn't want to idle. With the choke on, it starts right up, but no matter how warm it gets, I can't take the choke off without it dieing. 1,600 rpm is about the lowest it will run. I'm only able to take the choke off if I hold the throttle open enough to stay at the high rpm, any lower and it just shuts off.

The propane trick to look for a vacuum leaks wont work because the fan is blowing too much air past the engine. There's only two gaskets anyway, but the intake could be cracked somewhere out of sight.

I'm out of ideas. What should I look at next?

 

Sounds like not enough fuel at idle.

Did you do anything to the carb??

 

The carb still has the same setting it came with. The float bowl and need valve were cleaned recently as it was sticking open and flooding. I was under the impression that they only way to adjust the solex was to change the needle and seats, which hasn't been touched yet.

 

I'd guess plugged up idle jet...

 

I would try a different carb. Had the same problem with my m38 turned out to be the carb.

 

My cj2a had a crack in intake cleaned carb 3 times be for I spoted it.

 

I've taken the intake off and looked for crack. Couldn't find any. The rectangle gasket between the intake and exhaust had a crack, but it wasn't actually leaking. I even filled the intake with water to see if there was a crack somewhere out of site. Nothing. Looks like it's got to be the carb. I've got most of five carters laying around, including one I tried to rebuild, but the cross shafts are worn down and will certainly leak air.

 

If it were mine, I'd take the carb apart and clean it with spray carb cleaner - Berrymans is good. Also look for vacuum leaks, ie base gasket and elsewhere. Think of it as field stripping your carburetor!