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Thread: V6 Cylinder Head Porting Choices

  1. #1

    V6 Cylinder Head Porting Choices

    I'm looking to pick the collective brains in Racing Junk.

    I already did the obvious. I've contacted Curtis at RFD, Mike Lane at Champman, and the team at HRD Racing Heads. Everyone was nice, but none could help me out.

    I am looking for someone who might have a good CNC program for a set of GM V6 raised runner heads. I also wanted to know who else other Racing Junk members would recommend.

    I've got a 4.8L (295ci) Chev Odd Fire V6 I'm putting together for a 80% strip/20% street car. The car is a tube chassis Triumph Spitfire. I currently run a 4.3L even fire V6 on 93 Octane fuel using a small NOS system (up to 150HP shot). The new engine is a Bow Tie block and has a bore of 4.155, stroke of 3.625, with a compression target of close to 11:1 or just slightly above. Car weight is 2350lbs with me in it. 3.91 rear gear with a 24" tall tire. Goal is drive to the track, swap on slicks, run a mid to low 11 et with out the NOS (density altitude is usually around 4800 to 5000ft), then swap back to street tires and drive home.

    The heads I have are GM Bow Tie Aluminum casting #14044883. These are a bare casting without seat and guides. They are 23 degree, .200 raised intake runner with 55cc combustion chambers. From what I understand reading the Chevrolet Power Manual (6th edition - 1988) they were popular with oval track and road racers in the late 80’s to late 90’s. The heads will accept tapered seat or gasketed plugs. The rocker stud holes are relocated .058" towards the intake manifold flange to produce correct geometry for .100" longer valves (or .200” longer according to the 7th edition of the Chevrolet Power Manual). The pushrod holes are deleted to allow the use of offset rocker arms if desired but the heads will still work with standard rockers (again, according to the books). The manual suggests porting modifications should follow the same general guidelines used for raised runner GM heads.

    Intake being used is a GM 2 piece box style Bow Tie intake (part #10051125 & 26). This is a cross ram, high box volume, air gap style set up. Carb will be either a 650 or 750 CFM Holley based 4150HP (Quick Fuel or Biggs Stage 5).

    The roller camshaft has not yet been picked because the heads have yet to be touched. I'm thinking something .580" to a max of .650 lift (using a 1.6 rocker), between 250 to 260 duration (@.050) with a 108* or 110* separation angle. RPM would be up to 7000 to 7300 max (the lower the better). The smaller the camshaft I can use the better to keep it streetable, but I still need to make the power.

    Thanks for your help and advice.

  2. #2
    Senior Member DYNO OPERATOR
    Join Date
    Nov 2006
    I wish I still had Bob kaiser's ph# He did tons of v6's for comp racers in the northeast. Try Jenkins competition, they also have done a ton of them also. There in Malvern Pa. ( this is Grumpy's shop) David.

  3. #3
    Senior Member RACING JUNKIE
    Join Date
    May 2003
    Coldwater, MI
    Jerry Arnold would be on the top of my list. He has a TON of hands on with 4 and 6 cyl stuff
    David Lanning
    IHRA NHRA 387B

    Fleenor Racing Transmission
    Lanning Electric
    Complete Drag Car Wiring
    APD Race Engines

  4. #4
    I tried to look up Jenkin's shop on the internet but the web site only sells shirts.

    Who is Jerry Arnold and how to I get in touch with him?

  5. #5
    Senior Member RACING JUNKIE jmarksdragster's Avatar
    Join Date
    Jul 2007
    Try asking on Speedtalk, one other to check is Larry Meaux.
    Mark Whitener

    Good work isn't cheap, and cheap work can't be good.

  6. #6

    V6 porting

    Tom Slawko does all of Bob Kaiser's heads. 610-286-1822

  7. Racing Junk

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