Advice on Idle Setting
 

Need some help. 76 911 S 2.7 (CIS) - Wanting to increase my idle a bit, and my idle screw doesn't have any effect. Can turn it all the way left and all the way right, and it doesn't alter the idle a bit?
I'm also playing with the fuel mixture (which does have an effect)?

Getting some dropping idle, and some popping/sputtering.


Any advice? Thanks!

1. Richness must be set correctly. Sounds like you're lean. I always use CO gauge (but I've had members say they do it by smell!)
2. Are you sure it's the idle screw you're turning?
3. If 2 then, you're no getting enough air flow, most things, AAR failure or air leak, cause high idle.

If you don't have a gauge, you can try setting your CO by pushing up on the air flow sensor plate, once the engine is warm and running. If the revs rise, you can go richer. Then pull down on the plate. If the revs rise, you can go leaner. If you push up and pull down and both times your revs fall, then you are good. Then you can set the idle.

If you still get no change, then the air leaks or faulty AAR Hladun mentions may be the problem.