Ok, I just put a Holley 4160 600 cfm w/hand choke on a 85 Z28 305. After I put it on and fixed the vacuum lines, the car fired right up and was working fine. I set the mixture screws and idle speed to what I thought was good- the fast idle @ 1700, reg idle @ 1000, and 650 in gear. I drove the car for three days and the settings stayed the same, and the car drove great. But starting yesterday, the car has been harder to start, and the car is idling @ 500-600 rpm's in nuetral and in grear. I've heard that Holley's need to be turned often, but is this normal? Should I bring the idle speed up more, or is there a problem besides the idle speed screw?


1985 Camaro Z28 305 V8 w/ Holley 4160 600 cfm carb w/vac secondaries, manual choke, no cat, aftermarket muffler, 1" phenolic spacer, no egr, no smog.

 

Did you kit the card before install? Might check float level. Check for vac leak but that will make it idle high.........readjust idle screws approx 1.5 turns out varies with engine ..........check without air cleaner top to check air cleaner restriction.........Bill

 

i've had my holley on my car for a full summer without having to tune it but a few times (and that was only cause i had to face emissions) and it ran perfect for me..

are u using your choke? sounds like your engine is trying to get fuel, a culprit is cold weather... cold weather without a choke can kill a cars idle

 

Couple of easy things to check, that can change idle speed. You didn't mention any other driveabilty problems ...but has it started to run a bit rich?

1) Check the float level with the car running. Fuel level should be at, or slightly below the bottom threads of the sight plug on the float bowls. My preferred settings are 1\16 below threads on Primary side and about 3\32 below on the Secondary.

2) Tighten the float bowl screws. These tend to loosen over time...usually not in a few days...but they might not have been fully tight to begin with. Snug is not good enough. They have to be pretty darned tight. Otherwise the gskts on the metering block may leak internally.

3) Give the airbleeds in the airhorn a good cleaning with carb cleaner. Over time these tend to varnish up with fuel deposits...but all it takes is a small ( very small ) piece of dirt to partially plug one of these and then your mixture goes out of whack. The idle air bleeds on the Primary side are particularily succeptable to this.

Edit: Spelling

 

Where'd you hear that?

The only "tuning" I do to mine is when conditions change (like going from 5800' elevation to 700', or hot summer racing vs. cool fall racing) or I've changed something else (like cam, or porting the heads).