Help me fix lean on power issue - Holley 4150

Fuel and Air Systems

  1. wsutard

    wsutard Well-Known Member

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  2. beanhead

    beanhead FBBO Gold Member FBBO Gold Member

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    Yes, and I always measure the bits at the shank with a caliper to verify they're the size they're supposed to be, and make a chart/list/whatever. It helps for reference or if the drill index spills (it happens LOL!)
     
    • Agree Agree x 1
    • 68 HEMI GTS

      68 HEMI GTS Well-Known Member

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      Yes, you’ll need a numbered drill set
       
    • wsutard

      wsutard Well-Known Member

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    • wsutard

      wsutard Well-Known Member

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      @68 HEMI GTS I just checked my new proform metering block and it isn’t tapped already for the lower holes. They look like they will be tricky to tap.

      Question, if this is what is needed to properly tune a Holley then why doesn’t Holley make these ports tunable?
       
    • beanhead

      beanhead FBBO Gold Member FBBO Gold Member

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      IFRs on the bottom are usually better, but if they're in the high position just go with them for now. Or did they not give you replaceable IFRs at all? I would think an aftermarket block would?

      Here's the factory stock primary block from a Quick Fuel '750 Street-Q'..
      20190910_175305.jpg

      (You want the 1/8" long screws btw)
       
    • wsutard

      wsutard Well-Known Member

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      Are brass mandatory or can I use stainless set screws? I can’t find any brass local, just stainless. I understand that stainless will be harder to drill out.
       
    • beanhead

      beanhead FBBO Gold Member FBBO Gold Member

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      Just me, I wouldn't use stainless...you're correct that they're harder to drill, but the bigger issue is they will not get along well with the metering block material. You can get brass from McMaster-Carr. Summit also has quick fuel branded blanks, part# 7-25-10QFT. But- these have a small head on them, so you may have to drill the first part of the hole slightly bigger to accommodate.
       
    • 68 HEMI GTS

      68 HEMI GTS Well-Known Member

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      Beanhead is correct. Those little drills will never go through the stainless. Gotta use brass.
       
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