Holley carb adjust
Thread Starter
Racer
Joined: Dec 2007
Posts: 445
Likes: 2
From: Thomastown Mississippi
Holley carb adjust
'77 stock 350, Holley 4160-600 cfm. Can someone give me a starting point for adjusting my air mixture screws? The guy at Autozone said he thought it was 1 turn out. someone else told me 2 turns out. Right now I have it set at 1 3/4 turns out and it idles pretty smooth. If I back it out to 2 turns it's smoother yet, but I don't want to run it too rich or lean. Also, does backing out on the screws make it run leaner or richer??? Thanks,
Kenny
Kenny
Advanced
Joined: Feb 2008
Posts: 88
Likes: 0
From: PORT ST LUCIE FLORIDA
connect a vacuum gauge up to manifold turn the screws in, then back them out one turn, start the car turn the screws out evenly until you get the highest vacuum reading turning the screws in leans turning them out makes it richer
Last edited by tjl82; Jul 4, 2008 at 08:08 PM.
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
The installation instructions for the Holley 4150 state, "As a starting point, set the needles 1½ turns out from full lean position, then adjust for best idle."
The 4150 is very similar to the 4160; they are absolutely alike in operation. The 4150 has a secondary metering block vs. a secondary metering plate for the 4160.
Cheers,
Pete
The 4150 is very similar to the 4160; they are absolutely alike in operation. The 4150 has a secondary metering block vs. a secondary metering plate for the 4160.
Cheers,
Pete
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
with all of the above. Start the engine and bring up to normal operating temps and ensure the choke is fully open. Use a vacuum guage if you've got one. If not, still start with both screws 1 to 1 1/2 turns out. Keep adjusting both screws out 1/4 turns at a time until you achieve the highest idle RPM. Afterwards adjusting the needles you'll need to readjust the idle RPM using the throttle adjustment screw, not the needle screws.
Thread Starter
Racer
Joined: Dec 2007
Posts: 445
Likes: 2
From: Thomastown Mississippi
Thanks for the info. Went to AutoZone and borrowed their vacuum guage. Got the carb dialed in now. With the new valve springs(after one broke) and the carb adjusted correctly, this old original motor is purring like a kitten again. Thanks for the help.
Kenny.
Kenny.
