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  •  » Need to rejet the new Holley

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    9/02/2024 7:39 PM  #1

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,171

    Need to rejet the new Holley

    670 vac secondary on my 66 427. 
    A/F ratio gauge sits at 12.8 at steady 60 mph. Around 11.0 at full throttle second gear.

    I’m thinking about two jets sizes smaller in the primaries should get it close. 

    Whaddaya think?  I figured the collective experience of this group might help me dial it in with fewer jet changes. Will address the secondaries after the primaries are closer to right. It is going to be hard to beat the way it runs right now.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    9/02/2024 9:52 PM  #2

    rpm
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    From: Bakersfield, Ca
    Registered: 9/17/2013
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    Re: Need to rejet the new Holley

    For being that far off I'd jump four jet sizes on primaries, and two on secondaries.

    Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
     

    9/02/2024 10:45 PM  #3

    Cab4word67
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    From: Portland, Ore
    Registered: 4/06/2019
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    Re: Need to rejet the new Holley

    Well from what I remimber about carbs is if you go to lean in the primaries it will surg at part throotle then go up one size after you get rid of the surg. 

    Slammed Big Blue, ran over the varmints that messed with the Stang. Now all is good in the NW
     

    9/03/2024 6:28 AM  #4

    TKOPerformance
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    From: Newark, DE
    Registered: 12/15/2014
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    Re: Need to rejet the new Holley

    We always used to tune by going up or down at least 2 jet sizes at a time.  A single step up or down was for fine tuning once we were close.  But since you actually know the A/F ratio and its pretty far off I'd agree with rpm and drop down 4 and 2.  I'd want to see near stocih at cruise and 12:1-12.5:1 at peak torque. 

    I'm guessing you're running 32-34 degrees total timing?
     

     

    9/03/2024 8:31 AM  #5

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Need to rejet the new Holley

    Thanks, guys. Will let you know how it turns out.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

    9/03/2024 10:27 AM  #6

    rpm
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    From: Bakersfield, Ca
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    Re: Need to rejet the new Holley

    What are your idle numbers?

    Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
     

    9/03/2024 1:05 PM  #7

    MS
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    From: Canyon Lake, Texas
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    Re: Need to rejet the new Holley

    rpm wrote:

    What are your idle numbers?

    13-14

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

    9/03/2024 2:06 PM  #8

    rpm
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    Re: Need to rejet the new Holley

    MS wrote:

    rpm wrote:

    What are your idle numbers?

    13-14

     
    👍

    Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
     

    9/03/2024 5:44 PM  #9

    Steve69
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    From: Madison Wisconsin
    Registered: 4/01/2013
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    Re: Need to rejet the new Holley

    When I called Summit Racing they also said two jet sizes.  I was adjusting my idle mixture screws yesterday and I can get them perfect near 14.7.  Then drive the car again and there to lean. Seems like they’ll never be consistent.

     

    9/03/2024 8:27 PM  #10

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Need to rejet the new Holley

    Went with two sizes down. It now has 66 primaries./77 secondaries  Running ar 2,000 rpm (while parked) it is at 13.8, so maybe another two will get it there.  I was able to get the idle near perfect.

    Will test on the road tomorrow. It was raining (!!!) tonight when I got it back together. I am not sure how being under load will affect the A/F ratio vs sitting still.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

     

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