Air fuel screws all the way in and the car still runs...

[nhra6284]

I have renewed a couple dozen qjets over the last 20 years or so. Of those, I have had 3 that the air fuel screws could be turned all the way in and the car still runs. In the past I have tossed the carb aside and started over. I have one now that is doing the same thing and I have decided I need to figure it out. So, I bought Cliff's book and read through it. My assumption is that I am getting too much fuel through the idle tubes, but I know this can be effected by the air restrictions also. So my question is, where do I start? Do I downsize the restrictions on the bottom of the idle tubes? Or increase the air restrictions? Or?

[Cliff Ruggles]

Too much idle fuel is not necessarily the issue when you don't have control with the mixture screws.  More often than not, the idle tubes are plugged up, or carb doesn't have enough idle fuel, and is on the main system instead of the idle system.....Cliff

[nhra6284]

I will be pulling the idle tubes and measuring everything tonight...

[nhra6284]

Ok... Small end of the idle tubes are .040. The downtube restriction (brass cups) are .0595. Upper and lower air restrictions are .070. The air fuel mixture holes are .0995. The carb number is 17080212. Engine specs are: sbc 350, 9:1 comp. indy ss 1.94/1.5 valve heads. Howards can #112141-10. Intake @50 231, ex @50 235. lift is 480/488 weiand single plane intake.

[Cliff Ruggles]

Those are pretty generous settings for idle fuel delivery.  Do you have any control at all with the mixture screws?  The engine should slow down when they are turned in, but it may stay running having some fuel coming from the transfer slots even with the screws seated....Cliff