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4 valve heads on a 2 valve motor?

Discussion in 'Technical Q&A' started by Birdman, Dec 12, 2003.

  1. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,683
    North shore, MA
    Full Name:
    THE Birdman
    Hi Everyone,
    So I was giving this some thought today just for fun and I thought I would ask the experts if the following is possible and if so, would it do anything?

    What if one were to put a set of 4 valve heads/cams from a 308 QV engine on a 2 valve carbed engine, resulting in a carbed engine with 4 valves? I'm thinking that the improved flow with the right jetting would produce a chunk more horsepower. Is this possible? Will the heads fit? (I have no idea where you could get the heads or how much they would cost, but...)

    Birdman
     
  2. Dave

    Dave F1 Rookie

    Apr 15, 2001
    2,722
    Little Rock
    Full Name:
    David Jones
    Or you could just put carbs on a QV motor.
    My experience shows that if you want 4 valves per,
    then it is best to just get a whole motor.
     
  3. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    qv heads will not fit on a 2v motor due to passsageway mismatch
     
  4. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    The answers are No, No, No, and No.

    The QV heads won't fit, as the stud patterns are a bit different. And, carbs won't fit against the QV head w/o a custom manifold. Check the archives, as someone made a manifold to adapt carbs to the later heads.
     
  5. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    Modena Engineering(Frank Capo) made carb manifolds for 3.0 and 3.2 qv engines. Most were used to adapt the TWM FI Throttle bodies (see ric rainbolt's page for pictures).
    I have a set of 40 DCNFs on my 3.2 qv - conversion documented in this and old board, now in 6 parts.
    Fchatter Paul Sloan is putting IDFs on a 308 qv now.
    Conversion from Kjet to Webers very popular with 2.7 - 3.0 911s.
    I think there is a qv in Oz with Webers, but only third hand.
    hth!

    best
    rt
     

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