'71 911T Idle help!

[archtech]

Having an annoying problem with my idle once the cars warms up completely. When I first start and go on a drive it seems fine. After a 20 minutes of driving, when I come to a stop, the engine is still idling over 2000 rpm and then slowly comes back down. After 30-40 minutes of driving, it never wants to come down. I blip the throttle and it still doesn't come down. The engine is a 2.2 liter with solex carburetors. Any advice is greatly appreciated!

thanks!

[gamin]

Solex carbs? Do you mean Zenith carbs? Anyway, I had very similar problem many years ago with weber carbs on my 2.2. Turned out to be one or more of the butterfly valves somehow became misaligned and when everything got hot would bind slightly open. Look down the throat and you will see that they are held in with 2 screws which I am led to believe allow for some small adjustment or maladjustment. Speaking of heat, do you have the spacers between the carb base and intake manifold? Might keep some of that heat out of the carbs.

[archtech]

Sorry, yes Zenith carbs! Next drive I will check to see the butterfly valves before and after.... makes sense! As for the spacers I have them between the engine and the manifold, but not between the carb and manifold. I'll look into them too. Thanks!

[Eric_Shea]

I had this problem with my 911 motors over the years. I don't recall how my Zeniths worked but, I'm very familiar with the situation on my Webers.

If the idle adjustment screws are turned past 3/4 turns your butterflies can move into the transition circuit. Once that happens the car will want to hunt into a higher idle once it warms up.

Check your idle set screws and make sure they are not turned too far. Set your idle when your engine is warm. If you can't get it to idle with the screws adjusted out to 1/2 or 3/4 turn, check your idle jets and idle circuit to make sure nothing is plugged. You may need to go up in idle jet size and... Use your hand throttle when the engine is cold.