Holley carbutretor question

[Jim Werth]

I have a 700 holley double pumper on a 351w. Can't get it to idle down. Secondary throttle plates don't close all the way. At idle I can cover the primaries with my hand and it still runs. Cover the secondaries and it quits. Set screw for the secondaries is backed off so its not that. Is it worth a rebuild or is their an easy fix? Should I just replace it with a 670 Holley Street Avenger? Thanks Jim

[Monster]

Jim,
You didn't say whether you had a vacuum or mechanical secondary. If you have vacuum you may have too weak of a Diaphragm spring. The spring controls the opening rate of the secondaries and there are different spring rates available (a weak spring will allow the secondaries to open early). Holley has quite a bit of information available on their web site (www,holley.com) in the Tech section regarding setup and troubleshooting. You can also call direct to Holley and speak to a tech the PH#. is on the site. Be sure you have your carb model # (located on the choke horn in front of the primaries.

good luck,
Mike "monster"

[Jack21]

Also have 700 Holley DP (#4778) on 351W.

Sounds like engine is running mostly on open secondaries, and you need to find out what is holding them open. The only thing that is supposed to be holding them open is that set screw. The only thing I can think of is binding in the throttle shaft, or the throttle blades in the bore. You may have to loosen the throttle blade screws and relieve any binding in the bore.

I have a hydraulic roller cam which pulls 15" - 16" vacuum at idle. To lean it out, I jetted the primaries back to 64. Set the primary throttle blades under the transfer slot, then set the idle speed with the secondaries. Replace the secondary set screw with an allen set screw (10-32), and you can now adjust it on the car with engine running.

[Jim Werth]

Got it fixed. Throttle blades were not centered in the bores. Jim