Holley 1904 on 152 Tuning

[Albuq. Henry]

There are a couple things that you can look at..

First I would make sure that you get a good squirt of fuel when you operate the throttle. That will show if you accelerator pump is working, if there is not a good squirt, that might be causing your hesitation.

How do you know it is running rich? If it is, depending on how bad you will foul plugs, not get optimum fuel mileage exhaust will smell. Wont really damage anything just not run good.

One cause of running rich with this carb might be the economizer popped valve. They get worn and dont seat properly and constantly dump fuel. Over at IHONLYnorth forums there is a very detailed thread that talks about these carbs. I would read that over, its a sticky in carb tech.

There are some things to look at, along with all the other basic tune up stuff, plugs, wires, points, cap, rotor and everything adjusted properly, and no vac leaks. You said recently rebuilt but make sure all the adjustments after the rebuild are good. Is it at least running better after the rebuilt carb and dist?

[Natefank]

Yes I'm getting a good stream of fuel. Everything is running great. The reason I say it's running rich is that I can smell it. And the idle mix screw is out like 3 to 3 1/2 turns instead if 1 to 1 1/2 but if I turn it down it doesn't want to run right. Should I just leave it?

[Albuq. Henry]

if you screw them in does it die out? maybe you need to increase the Idle speed adjustment? I have been setting my idle mixture to get max vac. then adjust Idle speed and adjust mixture and Idle speed and so on...

Is it running rich when not ideling?

[Doc Stewart]

Your main jet may be too lean and you are compensating with a very rich idle fuel system. Main jet is usually #62 If it is smaller [lower number], change it.

You may also have a vacuum leak. With the engine warm and running, spray around the carb and intake manifold with brake clean and listen for change of RPM.

[Natefank]

Henry; yes if I go in or out with the screw it wants to die out. I don't have a vacuum gauge so I did what it says in the manual to do: screw out the mixture screw until I get the highest steady idle, which for me is about 3 1/2 turns out.
Doc; I'll check the jet and for vacuum leaks

[Albuq. Henry]

I would adjust the mixture screws to the 1 and half to 2 turns out then adjust the Idle speed adjustment to the 650 range then play with the mixture screws from there.... See if you notice any improvement.

to know if you are too lean or rich look at your plugs.