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Four quarter turns out = one complete turn out on each idle mixture screw.



Bullit:

If I understand correctly each of the four idle mixture screws is one complete turn (360 degrees of rotation) counter-clockwise from being lightly seated, correct?

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Is the throttle stop the same as the idle adjustor?



If I understand your question correctly, the curb idle screw (also might be called the idle speed screw) is on the drivers side, and points up at a about a 45 degree angle.

The term "throttle stop" more commonly is used to describe a similar screw on the secondary (rear) of the carb. Most point straight up, requiring you to remove the carb to access it.

BSB67 asks some valid questions, including "how do you know it's rich?". Since most Holleys are too rich, especially at lower loads/RPM, when you asked about "rich", I began answering about "rich". Seemed reasonable to me. An engine that is idling lean also makes a smell, but it's entirely different. Are you familiar with the difference? If I was a betting man, I'd still have money on "rich", but since none of us are there to take in the sights, sounds, and smells as you try to tune this carb, we have to ask questions that may seem over the top to you.

It would be easy to verify whether it's too lean. Just get some 60 or 65 air bleeds and swap 'em for those 75's in the carb now. If the problem gets worse...it was rich to begin with.

I'd really like you to pull the metering blocks and measure some holes. To measure them, you'd need a set of numbered drill bits. You use the shank end of the bit (the end that normally would insert into the drill) and find out which bit fits the hole the best. I can post pics of the holes you'd need to measure. How comfortable would you be doing that? Do you know anyone from whom you can borrow a set of numbered drills?

Jim