School me on Holley double pumper adjustments

[dave73chally]

I have a freshly rebuilt Holley 850 double on my 512. Ran great when the weather was warmer but it's getting colder out now and it's acting up.

On cold starts, when I start the car, I need to hold the gas pedal down for about 30 seconds at 1000 rpms or it'll die. Once it's warm, it idles nicely at 750 rpms. If I shut it down and fire it back up, no issues.

What do I need to adjust? It has an electric choke set at the middle setting. Does the choke need to be set richer? Adjust the fast idle screw? Looking for all the advice you have.

[dodj]

It has an electric choke set at the middle setting. Does the choke need to be set richer?

Probably. You have a fast idle adjustment as well. You may need to bump that up as well. It's on the passenger side of the carb.

[Chryco Psycho]

yup just more idle speed assuming the choke door is fully closing when cold if the choke door is open in 30 seconds but it still runs well no prob , if it starts to die as soon as the choke door opens you can turn the setting more to the rich side , but it is just wasting fuel if it opens faster & runs well still

[dave73chally]

Is adjusting the fast idle screw all trial and error or will turning the screw a specific amount increase the rpm a specific amount?

[Strawdawg]

Not sure Trial and Error is the correct term, but maybe Try it and See....it all depends on your total combination for the most part

[YO7_A66]

 Test a higher fast idle by 1/4 of a turn and see if you like that rpm.

The electric choke housing has marks. One on the black plastic cap and around 8 or so on the housing. Adjusting the black plastic cap rearward is richer. See what notch you are on currently, then move it two more notches and retest.

[dave73chally]

I adjusted the fast idle screw and now it'll idle at 1500 and stay on until it warms up. It takes about a 30-60 seconds to kick down and then it idles nicely at 750. For that initial minute of fast idle it's running rich, spews some fumes and really stinks up the garage. After it kicks down that goes away. Is there adjustments I can make to stop the rich condition at fast idle?

[HP_Cuda]

I think you are looking for this assuming you are using an electric choke:

https://www.youtube.com/watch?v=0H5IBSFgYJE