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Thread: holley metering plate

  1. #1
    i have a 4160 750cfm vac secondary holley, i want to convert it to a metering block on the secondaries. my problem is where to start with the jets. what is the jet equivalent of the metering plate? i need to go up a few sizes.

  2. #2
    There's a two digit number stamped on the metering plate...usually upside down. Find that number and I can tell you a main jet equiv.

  3. #3
    it looks like it says 21, does that sound right?

  4. #4
    A #21 metering plate has a .081" main jet and a .040" IFR

  5. #5
    Look here to see what the 750's normaly have in them with the metering block.
    MORTEC (
    I have a 750 VS Holley that I put a proform body on and used a metering block in place of the plate. I started with stock jetting for a simalar 750, 72 primary and 76 secondary. I ended up with 75 primary and 83 secondary with a long yellow secondary spring and 6.5 power valve. Im running a mild 468 BBC in a big heavy boat and the carb seems to be working great for what I need.

  6. #6
    well, i was just over BSing with my neighbor and he pulled out a carb he was running on his big block nova. its a double pumper but thats all i know. is it the number on the airhorn that i need to know?

  7. #7
    Yup, the top numbers on the choke horn.

  8. #8
    well, the number is 4777S,looking at holleys website that looks like a 650cfm. i think i will give it a try though, cause it has bigger jets in it and id like to see what a mechanical secondary carb does.

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