Hey, I have a 67 gta convertible and like a moron I changed the old carb with a 2 bbl. The car runs well enough with just a little less power. NOw to my question. I put on a holley 2100 model that has a fast idle screw, two mixture screws and the idle. I need to know how to set the idle mixture screws. Seems I remember my buddy in the day turning them all the way in and then out 1 and 1/4 turn. Right now, my idle screw isn't touching the linkage so its not doing anything. I know the mix screws are out and the performance I get is sluggish take offs, loading up on gas, and just an overall "cap" on the engine. Can someone talk me thru setting those damn screws....I know I should have a tach and all but I don't,. Just hoping someone can help...thanks

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How are you? To set mixture screws this is what I do.1 and a half is a good starting point. To find the ideal setting I turn them in till the idle drops. Then turn them out to get the fastest idle speed. (By ear is ok). Once you have them at the fastest point turn them in about aquarter of a turn to make it a bit leaner. That way you won't foul plugs.

p.s. the idle stop screw should be a least touching the throttle linkage. If it idles very high you may have a vacuum leak.

 

Hook a vacuum gauge up to the manifold. Adjust the mixtures to get the best vacuum (same goes for the dizzy timing as well). The key is to keep the idle constant, however.

Sounds like you have a throttle stop problem keeping the butterflies open or a vacuum leak. You're going to have to pull the carb to check these adjustments. On the pass side of the carb, you should have a throttle set screw that stops the throttle shaft. It's inset and most people don't know it's there. When closed, the blades should be fairly tight, but there will be two transfer slots by the blades to allow enough air for idle. Pick up a book about Holley's like the one from HPBooks. It will help you with these fine adjustments. The Holley 2V will have pretty much all the adjustments of the 4V versions, with exception of the secondaries of course.

For real throttle response, you should think about a 4V carb. The primaries are smaller, which allows for high air charge velocities, which is what you need for throttle response.