1976 cj7 performance issues

[verrengia714]

I have a 76 CJ7 5.0, quadra trac 3 speed th400,all california emissions,rebuilt 2100 motorcraft carb, hei ignition. I am experiencing some off idle stumble and an overall lack of power. there may be a vacuum leak, or timing wrong (its at 5 degrees btdc to specs), also there is a disconnected wire switch coming off the top of the gas pedal which i thinks goes to the trans or tcase but i dont know what it does. what could be causing this stumble and lack of power. Any advise is appreciated

 

[drhicks]

I had a 1976 Jeep CJ7 at one time with the 258, same problem. Found I had a vacuum leak on the back side of the carb. Put a new gasket under it and gained a lot of power and a good idle.

 

[jeepboy45]

I have a 76 CJ7 5.0, quadra trac 3 speed th400,all california emissions,rebuilt 2100 motorcraft carb, hei ignition. I am experiencing some off idle stumble and an overall lack of power. there may be a vacuum leak, or timing wrong (its at 5 degrees btdc to specs), also there is a disconnected wire switch coming off the top of the gas pedal which i thinks goes to the trans or tcase but i dont know what it does. what could be causing this stumble and lack of power. Any advise is appreciated

The switch at the top of the gas pedal is a kickdown switch for the auto tranny. You can actually reach down and pull the switch and it will drop from third to second. Normally that is accompanied by your foot in the throttle...

Did you recently do a repair, mod, upgrade and THEN the lack of power (stumble) developed? Or is this something ongoing... If you just did a mod, you should check the mod and everything around it. Maybe you inadvertantly knocked off a vacuum line. Aside from that, it sounds like an ignition/timing issue to me.