Holley 670 carb - JETTING

[heathbirkendahl]

Anybody running one of these?

I just put one on a ZZ4 crate motor and its SUPER rich.

I need help figuring out what jets to put in.
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[eldogg]

Before you open your carb up, I have a question. Where is your timing set at? Is your throttle blades closing all the way?
I had a guy drop his truck off at the shop complaining of rich idle with his New 670 Street Avenger, so I hooked up my wideband O2. First thing I noticed the Ford kickdown linkage was keeping the blades from closing all the way. The screw that holds was hitting his linkage. I removed that and adjusted the idle screws and it was 13.2 afr @ idle.

[heathbirkendahl]

Originally Posted by eldogg

Before you open your carb up, I have a question. Where is your timing set at? Is your throttle blades closing all the way?
I had a guy drop his truck off at the shop complaining of rich idle with his New 670 Street Avenger, so I hooked up my wideband O2. First thing I noticed the Ford kickdown linkage was keeping the blades from closing all the way. The screw that holds was hitting his linkage. I removed that and adjusted the idle screws and it was 13.2 afr @ idle.

I checked it and they are closing fine. It's looking like it just needs small Jets.

[69GWC]

I have one on mine and it needs to be jetted up alittle I believe, works great though zero problems with it.
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[NVBUYER]

This link will get you started:

http://www.holley.com/TechService/ListNumber.asp

Once you find your list number you can refer back to your instructions manual or download a new one located here [http://www.holley.com/data/Products/...0219-3rev3.pdf]. Inside the manual it will tell you what jets it came with for both the primary(s) and secondary(s). It will state on page 12 & 13 that you can usually step down one jet size for every 2000 feet gained in elevation but you will probably find that this isn't true for every carburetor.

[TBONE1964]

No vacuum leaks and chock is fully open? have to ask.

Try an 1/8 in turn on all the idle/air screws. Drive it hard and check the plugs.

Make sure you have the air/idle screws adjusted correctly. Jets usually do not cause a rich condition at idle.

Read the plugs. Tan is good.

[buckskins4ever]

I am running the same carb on mine. Right out of the box on my Vortec 355, needs fine tuned.........which goes to the dyno tomorrow to bring it perfect. I would gues you have a different problem other than jets though. You definitely are not over sized on the carb.

[Toxic Orange]

Check each of the idle air mixture screws for a consistent setting.Usually 1.25 to 1.5 tuns out gets you pretty close. Can you see a proper float level in the sight glass? If you could open that up should only be a trickle, not a flow. Whats your vacuum reading at idle? If its too low you may introducing fuel to your idle circuit from the power valve. Fuel pressure? Of course timing should be in order before any of the above. From all that I have read that carb should be right at home on your ZZ4 motor right out of the box.