Mixture screw has no effect.. What does it mean?

[darrell3001]

Very good news on the carb number 2 oddity. I successfully rebuilt my fuel petcock (from Z1Enterprises) this weekend. Problem solved! She absolutely purrrrs like a kitten now. I have been fighting this carb problem for well over 9 months now. I just could not get the idle dialed in the way i wanted it. Nothing i did made any difference. Valve clearance, carb sync, mixture screw, pilot jet swap. Nothing made any difference. I just could not get a good idle. I was very close to just trimming it to 1500 and living with it. The really odd thing was that the mixture screw on number 2 just had no effect. Turning it in all the way, no effect. Turning it out 5 turns, no effect. Finally someone suggested that i plug the vacuum hose from the petcock and recheck. BINGO!!!! The vacuum on the petcock was indeed opening the valve, but it was also allowing fuel to leak through the diaphragm, thus number 2 rich no matter what i did with the mixture screw. I rebuilt the petcock and the results are stunning. Idle is rock solid at 1100 now. I even trimmed it down to 900 and it just wont stall now. Absolutely amazing!!!

Bottom line: Test that petcock. Make sure its 1) opening the flow valve, BUT 2) also make sure its not sucking fuel through the vacuum.

I want to say "Thank You" for all the great support ive received from the group. Im already making plans to start on the next project that is patiently sitting in the corner of the garage (Red 83 11e).

Best Regards,

[darrell3001]

One last post on this topic. I went back and checked it was tom203 that suggested plugging the vacuum hose on number 2. Thank you tom203. I own you one.