Results 1 to 3 of 3

Thread: 750 HPVS Tuning Question

  1. #1

    Default 750 HPVS Tuning Question

    I have a 750 HP vacuum secondary carburetor. If I disable the secondaries so itís a two barrel, should I be reading 13-14 AFR at full throttle on just the two barrels? Iím getting around 15 AFR on the two barrels, but Iím getting 13.5 AFR on all four. Iím wondering if I should go up on the PVCR jets from the 71 I have now and down on the secondary main jets. Thanks.

  2. #2
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    2,012

    Default

    You have 13.5 AFR when the carb functions as a 4 barrel.
    The primary side is set to slightly lean side (15:1 AFR) to help with fuel economy.
    The secondary side is slightly richer to even it up (12:1 AFR) to give you 13.5 AFR.
    You could square it up a bit if you like, but fuel economy might suffer.
    Typically, the primary main and PVCR should be approximately equal in area to the secondary main. Gary

  3. #3

    Default

    Thank you. Thatís what I figured, just needed some verification.

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 NASCARģ Sprintģ Cup team and nearly every NHRAģ ProĖStock 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 dressĖup 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