[goatman65]

Non-stock 2g, 467 engine. Carb is very lean at idle, It is a nid-70's carb with large air bleeds in the top of the venturi cluster, .093. A/F gauge goes from 16's to 18-19 very rapidly at idle.

I found that if I cover the bleeds that I can get the A/F right in the 13.8-14.5 range,

Question is, will I really be fixing my lean idle circuit or will I cause other problems?

Also, it has .123 holes in the throttle plates. Would smaller holes give the same result as smaller air bleed holes? Or should I stop playing carb guy?

[steve25]

Air bleeds control the amount of air that gets mixed with the fuel that the idle mixture screws control, holes drilled in the throttle blades allow bypass air so that the throttle blades can stay in the range setting so as to have the fuel transfer slots still work right in the Carbs off idle setting, so two different things here.

[Aaron65]

I ended up drilling the idle jets (tubes) and IFRs a few thousandths in my '74 2GC to get a decent light cruise AFR. Mine was lean enough to miss a little (16.5 AFR at 45-55 MPH). It would lean out to 17 at some throttle openings. I didn't mess with the air bleeds, but I imagine it would accomplish the same thing. If your problem is only curb idle, can't you adjust the mixture screws to richen it out?

[goatman65]

It seems to need less air at idle and at low rpm, closed throttle such as coasting. Along with a lean idle it also bucks and surges bad below 2000 rpm with the throttle closed. Transfer slot are about .040. The tips of the idle tubes are at .052 which is the max they can be drilled. Don't remember the size of the IFRs.
Turning the mixture screws does very little to richen it up. The mixture screw holes are .095. I made metal covers to cover the air bleeds almost completely and the engine really likes it, at least at idle.

Right now the idle A/F is 13.6 and the idle is much better and I don't have to keep tapping the pedal to keep it running. Winging it at idle and throttle response is also much crisper and the engine just plain sounds better now. I just need to drive it with the bleeds covered to find out if I'm causing more problems than I'm fixing.

[Aaron65]

How big is the cam? I think I'd try closing up the holes in the throttle plates first before I shut off the air bleeds.

[goatman65]

Cam is fairly big, 256@ .050 intake. I don't think there is anything else I can do to richen it at idle/off idle except to reduce the amount off air some where.

[Aaron65]

I read through this article when I was modifying mine (although mine is just a stock, low-compression 350). Maybe it will help...

Any reason why you're running a 2-barrel?

http://www.hotrod.com/articles/ctrp-...g-carburetors/