holley idle settings

[patpend]

I have a 92 SN with a Holley and PCM. Previous owner sunk it. Ran well when I bought it 5 years ago, but idle got worse and worse. The carb was just recently (professionally?) rebuilt due to corrosion in the bowls. Prior to rebuild it wouldn't run at all. Now runs great but won't idle. No matter what I do the to idle jet settings it acts starved for fuel. If I hold the choke closed I can get it to idle at 750 rpm. Any clues?

[Rick]

The idle screws are located on the front float bowl they are silver screws inset into the bowl on the sides. I would close them all the way remembering how many turns it took to close them If it is unequal I would close the more open one to match the other. Start the engine and adjust one side until it just satrts to bog down and reopen 1/4 turn. Then repeat with the other side. If you have a vacumn guage close it down until the vacumn drops then do the other side. Adjust the linkage screw until it runs at approx 750 RPM. readjust the screws again

[nms1991]

patpend definatly check your idle mixture screws but also use spray some carb cleaner thru the airbleeds on the carb in the choke area. the airbleeds are the small jet looking holes in the choke area, the primary side the airbleeds are towards the front of the carb along the front edge. The idle airbleeds are the ones toward the edges on each side. you can try this if the idle mixture screws do not affect the running of the boat. If nothing works take the carb back to who rebuilt it and have them check over their work.

[patpend]

Rick and NMS 1991:

Thanks for the replies. The idle jet needle valves have no effect on the way the motor idles. I can screw them all the way in or all the way out and anywhere in between with no change.

So, I will try to find the airbleeds tonight. If that doesn't work sounds like another down week while I wait for warranty work.

[marks]

Hi patpend,

Sorry if I am asking the obvious, but did you try adjusting the idle level screw too? The idle fuel valves don't have much effect until you get the idle level in the ballpark. You have to ping-pong between adjusting it and the idle fuel valves, as Rick mentioned.

Also, you should verify your engine timing. I put a new carb on my boat this season and was having trouble adjusting the idle fuel and the idle RPMs. I finally decided to check the timing and found that is was almost 10 degrees retarded. Once I got the engine timed, everything came together.

Mark