Jetting starting point 512 six pack

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    Author Topic: Jetting starting point 512 six pack  (Read 1486 times)

    Offline Cuda4u

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    • Posts: 43
    Jetting starting point 512 six pack
    « on: April 22, 2018 - 08:51:36 AM »
    Im looking for a basic main jet starting point before engine is fired up and first pull on  dyno.
    Based off RB block. 512 stroke, TTI 1-7/8” headers, MSD ignition,
    Front and rear carbs quick fuel metering plates, Center carb promax metering plate with vaccum advance blocked, Rear carb promax bottom plate for fuel adj without removing.
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    Offline onebadfish

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    • Posts: 404
    Re: Jetting starting point 512 six pack
    « Reply #1 on: April 22, 2018 - 11:07:18 AM »
    My 512 is a dynoed 623hp at 649 torque and was still running lean but I ran out of time (and money) when doing the dyno run. I have tweaked my set up since it was installed with a duel sensor A/F gauge . Have vacuum secondaries with the promax metering plates on front and rear carbs
    Front 84-84
    Center 66-66
    Rear 84-86 throttle side

    Originally I had 68 jets in the center carb but it was running too rich mid-range at 3500 feet above sea level Calgary) so I went to 66s

    Car pulls 12.5 at WOT and midrange cruise is around 11-11.5....too scared to lean it out too far. It runs like a scalded ape - pulls real hard and idles/starts great. I read that ma mopar staggered the rear jets from the factory so I did - whether it makes a difference or not I would have to spend time on a dyno.
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    Offline Cuda4u

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    • Posts: 43
    Re: Jetting starting point 512 six pack
    « Reply #2 on: April 22, 2018 - 12:12:46 PM »
    I will go wit what you have to start with. Thankyou
    I plan on full day when engine gets done in Edmonton.
    I’m getting the edelbrock intake ported so jetting won’t be staggered for now
    « Last Edit: April 22, 2018 - 12:15:05 PM by Cuda4u »
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    Offline onebadfish

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    • Posts: 404
    Re: Jetting starting point 512 six pack
    « Reply #3 on: April 22, 2018 - 09:24:48 PM »
    Good luck with everything. I think you will be bang-on with my set up however if the dyno is using 2 1/8 inch headers it will register lean. I just completed a 496 for a friend and we went with a 6 pack as well and we were up to 90 jets in the front and rear carbs and we were still showing lean on the dyno. I have 1 7/8 inch TTi headers on the cuda
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    Offline Tazinhawaii

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    • Posts: 76
    Re: Jetting starting point 512 six pack
    « Reply #4 on: April 27, 2018 - 03:09:50 PM »
    I have a 522 with six pack.  I was running 66's in the center carb and just went up to 68's.  I think I'm going to go back down to 66's as I too am running a bit rich at part throttle with the 68's.  My outer carbs are stock.  I am running AFR 240 heads and 1-7/8 long tubes and roller cam.  Haven't dyno'd it, but tuning with a wideband A/F.

    Derrick
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    1971 Cuda 440 six pack.  Original TX9 Black on Black.  Located in southern NH.
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