Holley Tuning HELP

*Vacuum leak could definately be an issue. Is something unplugged?
*Timing could be an issue too. Too much initial. You could try setting up with vacuum advance plugged just like you would do for a setting a stock engine to stock specs. Without knowing how radical the engine is, hard to suggest more on this front.
* Size will not be an issue for setting idle even if you had a 440 cammed for a 4000-8000 rpm power band.
* Stop looking at videos by 3rd parties. Maybe they know, but many do not. Get it from the horses mouth -
Use the Holley Lit. for information: Instructions for your carb here:
[ame]http://www.holley.com/data/Products/Technical/199R7948-5rev6.pdf[/ame]
Holley also has some "how it works" info on their website.
Best for "how it works" is Holley Carburetors and Manifolds by Urich and Fisher. Urich was VP of engineering at Holley.

* Not neccessary to reset the floats unless the fuel levels are wrong. This is a good first thing to check. Do this by removing the sight plugs. Fuel should be just shy of dripping out.

* Choke has two adjustments. One is the choke itself. If its an electric choke - rotate the housing. ( Electric choke means that the heating of the bimetal is assisted by the electric resistance heating. ) The other adjustment is the fast idle and kickdown. If the throttle is hung up on the fast idle screw, the tip of the main throttle screw (aka idle speed screw) will not be touching anything.

* The 1.5 turns out on the idle mix screws is an OK starting place. But anywhere from 1/4 turn to 1.5 turns out is OK for final setting. Test: If the mix screws are run all the way in (gently!) and the engine is still running, then the engine is idle mix is coming through the transfer slots rather than the idle port. In this case, the throttle blade needs to be closed more. I don't think this is the heart of your problem since you state the idle speed screw is already completey backed off.

* The more sophisticated way to approach the idle speed screw is to make sure the transfer slot is just slightly exposed below the throttle blade. This requires taking the carb off and looking from underneath. If it the transfer slots opening looks square, its ballpark correct. Anywhere from .015 to .040" could be correct depending on the width of the slot and your particular engine needs, but square looking usually does the trick.
- Then adjust the timing at idle and fuel mix to get the best power and vacuum. When shifted into gear it may need a little richer than in Neutral. In gear is what is important. Since its a manual, I'd set up it in N and then only if its dying as you let it into gear tweak the idle mixes an 1/8 turn richer.