Autolite 2100 idle too high

[JSH68]

After rebuilding the Autolite 2100 on my 68 (302, auto, 2bbl., non-air) I can't get it to idle slower than 1300 rpm- and this is with the mixture screws turned almost completely in and the timing backed down to 5 deg. advance. Needless to say, this does slow down the idle some, but it runs like crap. If I advance the timing to 8-10 deg and turn out the mixture screws, I can get a really smooth idle, but its at 1300-1500 rpm. This is with the butterflys completely closed and the idle and fast idle screws turned out to be sure they aren't the problem.

I've checked and rechecked for vacuum leaks and haven't found any (sprayed cleaner around carb base, throttle shaft bore, and everywhere else for that matter).

Any ideas?

 

[oscart]

Check for vacuum leaks. This will cause a fast idle.

 

[BlackGMC]

I hate to say it but it sounds like a vacuum leak! check the intake to carb gaskets, PVC connections, tranny connections (if your an auto), and distributor connections. I am not sure if you have factory AC, but my 70 has factory ac which the controls are vacuum driven. If you have a vacuum canistor check that was well. What kinda choke does the carb have, maybe it is sticking?

 

[StangDreamin']

Vacuum leaks +1. Hell, +4.

Ever get the carb really hot? I actually had a 2150 throttle plate/bowl assy warp once (loose screws and I pulled it off before letting the engine cool on my Gran Torino in late July).

Nobody I talked to had ever heard of this happening before. It was really hot and I kinda forgot to snug down the mounting bolts after putting in an aluminum spacer. Was just another reason to put on the new intake and Holley.

For sale, one aluminum carb spacer plate for a 2bbl Cleveland........