Any chance this cam will have enough vacuum for brake booster?

Discussion in 'High Performance Modifications' started by DENALI, May 2, 2019.

  1. DENALI

    DENALI Veteran Member

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    .......or should i plan on going to manual brakes? I was hoping to use a twin diaphragm unit off a Turbo TA disk setup if possible. THanks

    [​IMG]
     
  2. jeff swisher

    jeff swisher Veteran Member

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    238-248 @ .050 does not look all that huge to me as far as killing engine vacuum to the point that power brakes do not work.
    But there are other factors that need to be looked at like huge rectangular port heads vs some bowl ported 781 oval heads.
    The size of the runners and velocity through the runners will be a big factor as will engine displacement.
     
  3. DENALI

    DENALI Veteran Member

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    .030 over 454, 10:1 compression, fully ported and polished 049 oval port heads.

     
  4. 1980RS

    1980RS Veteran Member

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    Hard to say on that cam. The LCA is kinda tight for power brakes, put it on a 114° LCA and you will have more vacuum.
     
  5. jeff swisher

    jeff swisher Veteran Member

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    I had a 350" chevy and had 2 cams ground 218@ .050 the old 268H grind.. one on a 106LSA and the other was ground with the same intake closing point to keep cranking pressures the same and the dynamic compression would also be the same but cam #2 was ground on a 112LSA by moving exhaust lobe only.

    2" difference in idle vacuum.
    You will be fine with your cube and the what I consider small duration cam.

    I also ran a 235-245 on a 108LSA in a 355" and it had plenty of vacuum.
    I know small engine.

    I have seen bigger in the BBC 396" and still had enough vacuum
     
  6. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    Do you already have that cam? The 106 lsa will be your limiting factor. One option is to use a vacuum reserve canister, I've had one for years.
     
  7. DENALI

    DENALI Veteran Member

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    Yes already have it. Just putting the car together now after 3 years of no time to do it.
     
  8. COPO

    COPO Veteran Member Lifetime Gold Member

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    I can get 11-12" of idle vacuum with my roller cam with 10.2 cr.
    • Advertised Duration (Int/Exh): 278/288
    • Duration @ .050 (Int/Exh): 232/242
    • Gross Valve Lift (Int/Exh): .507/.507
    • LSA/ICL: 112/108
     
  9. 450bench

    450bench Veteran Member

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    I'd bet you'd be fine with that cam
     

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