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Thread: Vacuum secondary metering plate question.

  1. #1

    Default Vacuum secondary metering plate question.

    I have a 4160 marine version that's running lean on the primary side. I’m working on that, but I’m wondering what to do on the secondary side once I have the primary side figured out. What’s your opinion on metering plates vs metering blocks? Would there be an advantage to fitting a metering block on the secondary side so that I can use standard jets, rather than guessing on metering plates and possibly swapping a few of those out?

  2. #2
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    I prefer metering blocks myself. Way easier to change a main jet.
    Or go for my favorite choice, RapidJet blocks from BLP. Gary
    Regards, Gary

  3. #3

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    Oh man, I checked them out, that might be a little over my head.

  4. #4
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    What color is your carb? Shiny, or zinc dichromate? Perhaps this kit will help you: https://www.holley.com/products/fuel...s/parts/34-6SA. Gary
    Regards, Gary

  5. #5

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    Thanks for the response. I had to lookup zinc chromate, does that mean yellow in color? If so, mine is basic aluminum color. If it matters I don’t care about the color, yellow blue red, I don’t care. What I’m asking, is it worth converting from a metering plate to a metering block and are there any drawbacks? Seems like if I buy a couple metering plates of different sizes, I could just buy a metering block, but I’m not sure if there are drawbacks.

  6. #6
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    Certainly no drawback converting to a secondary metering block. Main jet changes are the same as the primary side. Jets are cheaper than metering plates. Gary
    Regards, Gary

  7. #7

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    If I change to a metering block, where should I start with the jets? Same as primary side, X bigger than primary side, any suggestions?

  8. #8
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    What is the list number of your carb? Generally, secondary main should be 6-8 sizes larger than primary since you should not be running a secondary power valve. Secondary main jet only, and block the power valve with a plug. Gary
    Regards, Gary

  9. #9

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    The carb has 80319-4 stamped on the horn. If I go with the Holley metering block you posted, do I need a power valve plug? Does it even have provision for a power valve? Thanks again for the help.

  10. #10
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    Your carb is 600 vacuum secondary, has 65 primary main, so I'd go for 73 sec main.
    Equivalent main jet choice from current fitted metering plate, page 4: https://documents.holley.com/199r8110rev4.pdf
    The new conversion block is not machined for a power valve, so no need for a plug. Gary
    Regards, Gary

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