Idling issues

[Scott Torvinen]

Just wrapping up the final details on a full restoration. I'm having a difficult time getting my low end idle to smooth out. Carb has been professionally rebuilt, everything new. Timing all dialed into specs. Vacuum good and steady. Car starts great but the idle fluxuates between 500 (almost dying) and 800. When I put in gear she dies. I took her for the first road test this morning. I had the keep slipping into neutral to keep from dying at the intersections. High end she runs beautifully. Pull up to and intersection in gear and she dies. Then, after she's good and warm, things change. I pull up to an intersection she dies. But, if I slip her into neutral when running temp, the RPM is now way up. Maybe 1500-1600. It will not come down off that idle rate until she cools down. I pulled the top off the ford two barrel to check float level. That looks to meet specs. I'm kind of stumped as to what to try next. If anyone has any ideas, please pass them on. Thank you - Scott in Duluth

[Ford Only]

I think you need to try a different carburetor to see if the problem is the carburetor. It sounds as though you are getting too much fuel into the carburetor but you say the the float level is correct.
I have had trouble with the float level in the Ford carburetors, it seems that the ethanol in the fuel causes the fuel level to raise and cause some of the problems you describe but only when the engine is warm.
I have had to lower the fuel level a little lower in some of my cars and others I have not had a problem.

[Finster]

I had a similar problem and over the course of two years I tried every adjustment possible. I found the additives were causing it to run rough. I finally switched to an Edelbroch carb and put the autolite 4100 in the attic for future use(sale of the car).

You cant really see it and it works great - Better fuel and smoother ride.

[silverbird58]

Vacuum leak below carb or hose or valve or intake .
while idling Close off air inlet With your hand To richen the fuel mix , If Engine Speeds up Any the idle circuit is weak . or fuel clusters top plugs leak >
the rear throttle plates adjust as follows , gap at rear plate stop is .005 " (5 thousands) . Then Screw upward one Full turn .
Next set proper RPM for front plates .
next adjust B9ae 12370-a advance For Zero advance pull At idle . the very Slightest hit of throttle Should advance the distributor