Carb Idle Mixture Adjustment

[inviolet]

I recently tried adjusting the 4 idle air mixture screws on my Holey 833 Hp double pumper. I felt the car was running way to rich, it hadn't fooled any plugs but in traffic the fumes would choke you, so I leaned it out.

Basically I loosened up all 4 screws and than ran them all in the same amount till the car stalled. After it stalled I backed them out a half a turn each, all 4 screws to the same amount of turns.   The car is defiantly running leaner now but it feels less responsive and doesn't pull like it use too. I also notice a temperature change while idling in traffic. I guess the only sure way to know if I leaned out too much is to check the spark plugs or through a O2 senor on the exhaust.

However to my knowledge the idle screws shouldn't effect wide open performance, at wide open throttle the jet size takes over. Am I right?

[brads70]

ya those 4 screws I set with a vacume gauge ( highest reading) If it's too rich you can change the jets.  Lots of things to adjust, power valves, squirters, pump cams. What do the plugs look like? All black? Does it bog at any spot on the throttle?

[inviolet]

it bogs down low. Feels fine up top.

Whats the right way to set the screws with the vacuum gauge?

[brads70]

I'm not an expert but I adjust them to get the highest vacum reading. If it's bogging off the line with black smoke out the tail pipe( getting to much fuel) I would try a smaller squirter and/or a smaller or later acting accelerator pump cam.  And the opposite if it's not getting enough fuel.

You might check the power valve to make sure it isen't blown too? ( pull off the metering block,then power valve) and backfires ?

[inviolet]

No back fires. no black smoke at low rpm, sometimes black smoke at full throttle, the power value I believe is a 6, which I believe is good to 12 to 13 pounds of vacuum at idle.

 So hook up the vacuum gauge to the intake manifold, then back out the idle screws, than turn them down slowly and stop that the highest vacuum reading?