Holley 390 adjustment

Reply Subscribe

Thread Tools

Search this Thread

Dec 16, 2008 | 10:54 AM

lordoflivernois

Thread Starter

Freshman User

Joined: Oct 2007

Posts: 38

Likes: 0

Holley 390 adjustment

I have a 79 F100 300, with a holley 390 4bbl., it idles really high, and no matter how far I turn the idle adjustment screw back it stays high.. in the manual for the 390 it show a high idle adjustment screw that works in conjunction with the choke. For some reason i dont see it on my carb.. and help would be great ... thanks..

Dec 16, 2008 | 01:36 PM

Harte3

Postmaster

Joined: Dec 2006

Posts: 3,603

Likes: 10

From: Spokane, WA

IIRC, when facing the choke housing, the adjustment screw will be behind the left side of the housing with the screw head pointed down. Also, check for vacuum leaks and linkage clearances before moving that screw. And, if the choke is set with the pointer straight up, move it 2-3 marks to the right before adjusting the screw and see how that works. Seems to be a Holley thing...with several I have had I found that seems to be where choke operation is the best or at least provides a good starting point.