idle adjustment on my zenith

[egbert]

hello,

I have a 911T from 1970 with zenith carbs. But if it runs idle , it runs uneven and i think on 4 or 5 cylinders. With higher rpm's it runs perfectly!

I have adjusted the valves propely, new spark plugs , good marelli and timing is set. I have set the mixture screws on 2 1/2 out as in the hand book.

Can anyone give some information how to adjust my carbs on idle because i think I am forgetting something??

[BK911]

2 1/2 turns is just an initial set up. You have to measure the airflow into each cylinder and adjust the mixture screws to even out the flow.

[911ctS]

Like what BK said... you will need a uni-syn or syncrometer to measure airflow at each stack while at idle and adj. air bypass screws. Then do idle mixtures. Also make sure you hand throttle is all the way down while adj. the carbs.

[steveW]

These carbs are usually worn and getting the adjustment right is virtually impossible.

Good idea - set it right at idle and then idle around the bends all day.

I say, stuff the idle and set it for best mid range - top end.