::Ken,
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::Last night i pulled the top of the carb off and looked at the screw you had mentioned. I also noticed there is another jet on the deck of the main body. Do you know what this jet is for and does this carb have primary and secondary metering? The reason i asked is because the adjustment screw that is attached to the metering rod hanger seems to have little efect until the last half inch of throttle travel(wide open). In other words the adjustment screw does not make contact with the stop until almost full throttle. When running the smog test i would say he only brings it up to 3k RPM and just barely opens the throttle.
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::This is what I observed when opening the throttle. The metering rod, adjustment screw, accelerater pump and hanger all moved together. The only time the adjustment screw would hit it's stop is at almost full throttle which leads me to believe that this is secondary metering and probably not causing my part throttle rich condition.
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::Also i did not attempt to adjustth the scew. It looked to be more than one turn out to begin with and that would be leaner than one turn.
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::I'm still open for any ideas. I'll be playing with it tonight!
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::Thanks
::John
::John, the other jet you see is for low speed. However I don't feel that could be the problem. They don't change in size with age and would be sized by design. I don't know if smaller sizes are available. The float level if high will cause some extra richness due to being easier for the air flow to draw the fuel. The float level is specified as 3/8" with the float tang resting on the needle. Only adjust the tang and not the lower limit tab. Also look close at the tang for a noticeable (wear dimple) where it rest against the needle. This can be smoothed with a fine ignition file then polished with a pencil erasure. Then check float level.
:..Mixture screw on these carbs I believe only control air as the fuel passages are fixed. So backing the screw outward should lean the idle and possibly help in leaning the transition to mid system (low speed) operation. If leaned to much there may be some off idle hesitation so live on the edge of this for inspection.
:..Barring somthing else going on,I'm out of ideas.
:..Good luck.
:...Ken
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::::I'm in Sacramento california and yes we even have a dyno for emission testing under load. In fact I was just headding out the door to adjust it so i can go by the smog shop on the way home after work tomorrow.
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::::John
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:::::...I've never heard of pass/fail on anything other than the Idle Test;)
:::...In Pa, some counties do the test on the dyno for 81 and newer cars. 75 to 80 is an idle test.
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::::Ken