Vacuum leak?

[bwmetcalf]

1979 CJ7 with new Edelbrock 1406 and AMC 360 and about 2500 miles. It has been running great but now idles high. I have no idea if this is related, but the problem seems to have started when the other day I started it up and heard what could be described as a backfire. It seems to still idle smoothly and after a cold start the choke does kick off. If I adjust the idle screw down I can't get a smooth idle; it seems to go from a high idle to wanting to die.

I don't have a tachometer but it seems to be idling at 1000 or 1200, but hard to say for sure.

Do I possibly have a vacuum leak? I'm going to pick up some carb cleaner today and do the spray test around the the base to test for leaks.

Any other ideas?

 

[Lumpy Grits]

You don't need carb cleaner to hunt for a vacuum leak.
A spray bottle of very soapy water works great. When the leak is found-You'll see the bubbles sucked inside.
When was the last time you confirmed the ign timing?
LG

 

[bwmetcalf]

Ok, I'll see about using soapy water. I haven't had the timing checked in about 1500 miles. I didn't think about the timing causing high idle, but I guess it could?

 

[Lumpy Grits]

Make sure the dizzy is clamped hard into place.
Yes-Rotating the distributor one direction or the other, will increase and decrease RPM.
Good luck,
LG