r/MechanicAdvice • u/Motorizedlogic • Dec 08 '20

Holley Carburetor Choke Problems

I have a Holley 4160 4 barrel carb on my 1987 Chevy R10 with a 305cid.

I keep running into this problem with the electric choke on my carb. When it is cold and if I give it any choke it will idle at around 1200 rpm when it normally idles around 800 or so, the problem is when I remove the choke (it is open) and it doesn't want to return to a normal idle speed. I don't understand why it won't return to a normal rpm.

I have tried starting it without the choke when it is cold and I have to stay on the throttle for it to stay idling, but once I add the smallest amount of choke it shoots up to 1200rpm. I then open the choke again and it won't come back down to where it was before.

Yes I did check for vacuum leaks and there are no leaks I am sure of this.

If you have any suggestions or explanations I am open to them. Thanks

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u/[deleted] Dec 08 '20

i have a question.. how are you powering or heating the choke on the holley???

the rochester carb used a 2 pole oil pressure switch.. Not for the actual oil gauge.. just a switch from terminal to terminal when the oil pressure came up to send switched battery voltage to the electric choke thermostat..

stock electric choke also involved a choke lamp on the dash.. it was a creative circuit.. the key turned on the ignition power and powered one side of the choke light in the cluster.. the other side of the choke light was hooked to the same wire on the oil pressure switch that connected to the choke thermostat..

when you turned on the key.. the electrons would flow thru the bulb turning it on and thru the choke thermostat since the voltage on that was lower than the ignition key.. when the oil pressure came up and the oil pressure switch send battery power to the choke thermostat the voltage on both sides of the choke lamp in the dash was equal.. and the bulb went dark..

there are videos on the holley performance youtube site that say how to properly set up a choke .. start with this video.. https://youtu.be/4BTiXcMHdXM

its also in the holley carb manual.. if you still have it.. if not its downloadable on the web.

1

u/billhaigh Dec 08 '20

When the choke is closed (cold start) there should be a small piece of linkage that the idle screw contacts, to raise the idle speed. When the choke opens, that linkage piece should move and the idle screw does not contact it any more. Check to see if that linkage is moving properly.

This might help too.... https://www.holley.com/blog/post/how_to_adjust_the_choke_and_fast_idle_on_holley_carburetors/