Alright, this seems kinda weird. When my car has been running for a while, the RPM's start to increase when it's idling. For instance, when I first start my car, in park at idle the rpm's are at about 11-1200. After the car is hot from city driving (220+) the rpm's in park at idle are closer to 1500. Is that normal? Any idea what causes that?

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1986 Z28
383 ci Stroker, Dart Sportsmen 2 heads, roller rocker arms, Crower Hot Street Beast cam, edelbrock 750cfm carb and performer rpm intake, Corvette Servos, shift kit and 2600 rpm stall convertor, 3.73 gears and Eaton limited slip posi rearend.

 

The idle is a bit high...and it should be the other way around..idle higher when cold (choke on) and lows to normal at normal operating temp. Is your carb electric or mech. choke? You need to set your idle speed. I like mine right around 700rpm. Start the car and let it warm up. Turn the idle speed screw until the car idles a 700rpm. There should be two idle mixture screws on the front of the carb. Hook a vacuum gauge up and turn one screw until it pulls the most vacuum...then turn the other screw identically. The idle may have change, so reset that. Then set the idle mixture again. Repeat until you get the most vacuum you can.

 

It has an electric choke.

 

Make sure the choke connection hasn't fallen out...if you have a drop base air cleaner housing that's a good possibility. That would cause and idle problem.