Results 1 to 4 of 4

Thread: Idle Problem

  1. #1

    Default Idle Problem

    870 Street Avenger. Car has always ran great, but never idled perfect.
    Idle mixture screws never had any effect, but it always idled.
    So I read an article that said increase secondary throttle 1˝ turns, and reduce primary throttle.
    Well, I only moved the secondary one turn and was able to reduce the primary.
    And the mixture screws do make a difference, but highest idle with mixture screws all the way in.

  2. #2


    You have a vacuum leak. YouTube has videos for testing.

  3. #3
    Join Date
    Nov 2014
    Ont. Canada


    It sounds like your primary shafts are too far open and uncovering too much of the transfer slot. The transfer slot is feeding it fuel and making the idle discharge holes ineffective. Pull the carb and take a look.

  4. #4


    Well I checked the floats, pulled the plugs out, turned on the pump, fuel was weeping out of the holes. So turned them down till they stop weeping, not sure if that did anything.
    Well I turned the secondary shaft closed 1/2 turn, and the primary open to get idle speed, and now the mixture screws work and best idle yet.
    I guess it was finding that sweet spot with the secondary shaft, so the right amount of air is going through the primary.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us