When I first got my motor running, I had a real rich idle. I stuck some small wire in the idle feed restrictions and it helped, but made my cruise terribly lean. So then I opened up my secondaries but had to open them too far and it brought my idle way way up. I then drilled two small holes in the primary butterflies and closed the secondaries. The idle is good now but the lean cruise is back. If I accelerate hard the car launches, but if i pull out slow it stumbles and just about dies. On a real light cruise the air fuel ratio is around 18-20! I have screwed out the idle screws four turns now and it just made my idle richer and hasnt affected the cruise. I also went up on my primary jets and it hasnt helped. At a hard cruise/slight slight acceleration my air fuel ratio is high 12s/low 11s with the larger jets, so I really dont want to go any bigger there.
Where is the cruise circuit???Does it share the idle circuit until it gets to the transtion slots? Can I open these up and where do I drill?????
Maybe I just should have settled with the rich idle. My car would at least be driveable then.........

 

What kind of Holley is it?
Because i had the same problem with mine but i didn't go as far as you to fix it, i just screwed the idle mixture screws all the way in and it ran ok, but im getting my Holley re-built and tuned for my engine in a fue weeks.

 

Its a regular 600, but its on a 305 with an lt1 cam and low compression. My ignition timing is set to highest vacuum, which looks to be around 18*. I'm also blowing a supercharger through it but it doesnt affect anything at idle or light cruise. Im pulling 14 points of vacuum at idle, so I dont see why I have these problems. The holes I drilled in the butterflies were 1/16, it was still a little rich so I moved them up to 1/8. How do I fix part throttle????

 

is youre Holley new or did u get it used? because the person befor you could have used the wrong parts when building it, coz Holley parts are interchangeable and it could have the base plate off of a different Holley or anything.

I think that is one of my problems, my Holley is 40 years old this year :P

 

It was used, I rebuilt it. The thing ran fine until I changed the cam, and the low end tuning went to hell. I dont understand why it pulls so much fuel at idle, but not at cruise. Doesn't anyone know of a hole I can drill out a little????????

 

maby it is due to having the wrong base gasket, i have heard of people having this trouble because a jet or 2 have been blocked by the base gasket not having the holes in it.

 

that's possible, but when I rebuilt it, the kit came with four base gaskets and I used the one that matched up with all the holes. There was another one that was close but it covered up some holes.

 

maby thoes holes have fuel going through them but are not ment to for youre setup, like some things need them and some dont.

I duno just a thought.

I will make a call for you tomorrow, a mate of mine re-builds Holles and Q-jets for a job (he is gona do mine soon) I will ask him if he knows what is going on with youres


Sorry i tryed a fue times but couldent get hold of him, i will try again in a fue days.

 

I dont think thats the problem. Pretty sure I just drilled the holes too big. I went from 1/16 to 9/64. Quite a jump. Not sure how to fix it, maybe I'll just have to deal with it until the next motor.