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Old 04-27-2003, 08:24 PM
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Post Idle mixture screws only turned out 3/4. Runs good.

I have a 383 with a Holley 670 Street Avenger carb on it. Today, I decided to check eveything out, and tweak it a little. The carb is brand new, right ut of the box.

Anyway, I went to set the idle mixture screws, and this concerned me. I was getting 18 inches of vacuum at idle, which was the highest reading. I tuned the screws in utill it started to die, then cranked them back out until reached the highest setting. I discovered that I only have the screws out 3/4 of a turn. Most people start at 1 1/2 turns out.

Should I be concerened? It runs great, with no stumble or hesitation. Someone here locally mentioned that my idle transfer slots may be exposed. If this is the case, what is the remedy?

Can someone give me some details on how I should be setting the idle mixture screws. Maybe I am doing it wrong.

Thanks guys.

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Old 04-28-2003, 03:58 AM
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18" of vacuum sounds pretty good. If the idle transfer slots were exposed I think it would be less and a little rich. That usually happens when you aren't getting enough air to mix with the fuel mixture. It is usually on vehicles that have a pretty stout cam. The way it is usually dealt with is some small holes drilled in the butterflies to allow more air w/less throttle opening. It could also be from too big jets since initial flow is through the main jets, no idle jets. I would contact Holley's tech line with your specific set up, they are very helpful and can probably get you lined out.
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