Need help! New carb

[84step]

Hey guys could really use your help/advice on this one. Bare with me iam pretty new to this and this is my first carb swap. heres the deal, a friend of mine and myself replaced my old q-jet with a new Holley 670cfm street avenger. we got it on and somewhat tuned but what i have found is that if i have it i park the idle is fairly high i dont know the exact rpm because i dont have a tach but when it is either reverse or drive it goes down alot and the truck almost dies. It is driveable but when i stop it seems liek it dosent completley go out of gear and i have to hold the brake very hard or it will begin to roll, it also accelerated a little even when i do not have my foot on the gad pedal. Iam stumped so any help or advice would be much appreciated.

[J_PEPIN87]

Double check your vacuum lines make sure they're hooked up on the right port, happened to me once.

[85Bowtie]

Well, one thing, assuming you don't have a vacuum problem first, is with it in park, turn your idle speed screw out to lower the idle. Then you turn your idle mixture screws outward a 1/4 turn at a time on each side of the carb until your idle comes back up. When your idle speed no longer increases, back off about 1/8 of a turn and you should be there. Then adjust your idle speed screw back up or down until you get the correct idle in park.

Then see how it idles when you go into Drive.

You can hook a vaccum gauge up to your ports and turn the idle mixture screws in and out until you achieve the greatest vacuum if you have the gauge. If not, do it by ear like above.

When you turn one side of the mixture screws, you HAVE to turn the other screw on the other side of the carb the same direction AND the same amount of turn.

Hope this helps.

[mrh33916]

Does it have a electric choke? Did you hook it to the wire that went to the quadrojet carb? I've found that that wire won't work on a Holley, it needs to have 12 volts with the ignition on.

[84step]

Thanks for the quick responses and ill try them all, Yes it does have a electric choke i did hook it to the same wire, what wire will work then?

[mrh33916]

My neighbor has a '86 and we had the same issue, we ran a new wire to the fuse box. Some people attach it to the distributer wire. You can temporarily run it directly to the + post on your battery to tune the carb. then tackle the new wire later. Did that truck have a computer in it? If so you might want to change out the distributer to a non-computer version.