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Thread: should I match port my 396 oval port heads

  1. #1
    Junior Member SHOW GUEST
    Join Date
    Dec 2006
    Posts
    7

    should I match port my 396 oval port heads

    I was wondering if it is worth going through the hassle to match port my stock oval port heads while I have the heads off to change the valve springs to a heavier one for a comp cams big muther thumper cam. and will it make a big enough differance if I do the porting the motor is a 396 with a air gap intake ,headers, 750 holley dp, 400 tranny ,12 bolt rear with 4.11 gears ,3500 stall, its going in a 68 camaro right now the motor is out of the car so it wont be a problem ripping it apart

  2. #2
    Senior Member DYNO OPERATOR
    Join Date
    Feb 2006
    Location
    VA Hospital, Dallas, Tx (214 302 1924) cell-972-464-7400
    Posts
    540
    I am not a cylinder head ghru.
    Do not port match to header any exhaust ports on anything. That is more magazine bull. What you can do though is to use your header gasket as a pattern so you can blue the head and scribe the exhaust port shapes, SO YOU DON"T EXCEED THOSE BOUNDRIES, as you do port the exhaust, or clean them up. They will respond to a raisng of the port roof and a slight widening of the port, carefully smooth the valve guide bosses but don't get radical. I suggest to only clean the floor with sanding rolls. Carbide cutters are for cutting mass amounts of material and rough shaping the port. Smoothing and blending is done with cartridge rolls, which you can buy in a porting kit. Be careful and don't cut or sand too much, try to keep the same amount of cutting grinding, sanding etc, as close to the same on each port as you can. You don't want huge exhaust ports.

    Intake ports you can match those to the intake gasket if it fits the ports on the head. Careful don't go beyond this, better to be a little small than too big with an intake exit to the head. I persobnally on a mild engine, like the floor of the intake manifold to be a little smaller than the floor of the port runner in the head with tops and sides matched.

    You will find the best time you will spend doing amateur port work working the valve bowl areas to just blend it in and removing all the casting flash that is under the valves. Be very careful and stay off of the valve seat. I usually cut masking tape in tiny strips and stick those all around the valve seat for a little protection and also for me to see and watch as a guide.

    Careful when picking a cam for a 396. A cam that could be just a little agressive in a 454 could be too radical in a 396. I very strongluy suggest using a hydraulic cam and not a solid.

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.


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