Get the transfer slot for the primary throttle bore set-up when the carb is off the engine. You should try to set the primary throttle blade where the remaining opening of the slot is roughly a "square". Once you have it there, don't move the screw - tough to do I had to bite my own hand a few times to avoid putting a screwdriver on there! Photo below:

To get the proper idle speed - on many of the Holley vacuum secondary carbs ( I've learned not all) - there is a hidden screw beneath the base plate at the attachment of the secondary pot. this is at the lever where the pot operates the secondary blades.

Many manifolds and spacers have space to get at this screw - but it ain't easy. I typically replace the screw with a long one from the hardware store. So it sticks down into sight and you can grab it with needlenose pliers. The idea is to attend to these details before you put the carb down on the engine.
Just remember to maintain the position of the primary screw - and set the idle speed elsewhere. If the carb has an electric choke - take steps to assure it isn't interfering with your tuning efforts.

 



 
 Steve Metzger       Tucson, Arizona

This is nice to know. Has anyone used the Holley 570 cfm street avenger carb on there y block before that might be able to give so insite to tuning ? Any problem with jet size or accelerator pump adjusting. I have the Holley instruction but first hand knowledge goes a long way.
Thank everyone for you knowledge.

On a Holley, I've always used the port on the right side


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Ported at metering block.  Manifold under float bowl.  Put a vacuum cap on any port that you do not use..


Lawrenceville, GA

So if I am understanding ported line goes from dist canister to the connection on side of metering block? And the full port would go from dist canister to under float bowl ( and plug off the side source?
Thanks for your response carbs and tuning have neve been something I find easy to grasp.

Refer to your instructions but the ported vacuum port is near the top right side of the primary metering block and the manifold vacuum port is on the lower right, under the float bowl on mine.

As to which should be used, google ported vacuum vs manifold vacuum and decide for yourself.  Or, try both to determine the one that works best for you.

You want a vacuum source that is not disrupted by any other device, so the fuel pump is probably not a good place to hook it up.  Since the carb is already set up for it, use one of the carburetor ports.




Lawrenceville, GA

Finllay getting to the point of firing the Ford. Have a Holley street avenger 570cfm carb, 1” spacer on a B manifold with 57 distributor. What I am wondering is the vacum line from dist goes on side, but do you need to have a source for the full vacum connection on base? Should source be direct form manifold or can the connection on top of fuel pump workable if needed? Any other tips or trick for setup to start or for tuning?