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1968 B.B.Chev 427 truck head

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  • 1968 B.B.Chev 427 truck head

    Lots of talk about, tall blocks, why isn't the late model
    427 truck head ( being oval port, closed chamber) decent runners..being discussed..can l use these heads on other passenger blocks(396.-454) flat top pistons

  • #2
    i hve been out of the loop for along time,Im 60 semi retired ( retired with this virus), So I wanted to do a cheap BBC build to keep myself busy.Took it upon myself to try some porting,since these heads were almost free,i figured what the heck. So I couldn't find any info about these heads,lots of talk about crappy other heads being BOAT Anchors yada,yada
    seems to be a lot of parts available some reasonable prices.So I have begun bit by bit no real time line, its not a highpo deal,just a good cruiser with a bit of punch just for fun

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    • #3
      Not a BBC guy but some of the guys might have a handle on these. If I pull up a name I'll PM them.

      Dan

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      • #4
        You might get some better answers if you would provide the casting number.....that way folks will know exactly what you are working with.

        Otherwise, it's just a crapshoot.

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        • #5
          I built a 327 with small heads. Theory was port velocity over flow..it seemed peppier but peaked out..

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          • #6
            its always a balance of velocity vs volume.
            lots of volume=awesome hi rpm power, but
            may be soggy doggy & boggy off the line or
            at part throttle.

            velocity=good torque and 'peppyness' as the
            great deaf one described, but may run out of
            steam around 4000-4500rpm.

            that being said, john lingenfelter made +450hp and
            +600ftlb with 'junk' peanut port 454ss pickup heads--
            but i aint lingenfelter. odds are you arent either.

            the castings that say 'hi-perf-pass' are always a
            good starting point, rectangle ports have more
            volume whereas ovals have more velocity.

            for any hot street build (400-maybe 600hp) i would
            use ovals, for a 'kill' setup making 800+hp id use
            rectangle ports.

            if your going to port, the short side radius (exhaust
            port floor) is the achillies heel of BBC heads- thats
            why almost all aftermarket heads have the exhaust
            port raised .500-.750, to alter the radius and shape.

            that being said, a 10-1 piston 454 with oval ports and
            big valves with a decent cam intake carb and 1-7/8" or
            even better 2" primary headers would have to have
            something seriously wrong with it to NOT make an
            easy 400+hp/500ftlb..........

            hope that helps with your recipe.

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            • #7
              I thought I read years ago, that you needed spacers for the intake to heads when using short deck car intakes on a tall block h/d truck engine?
              My question is are the intake ports in the same spot on the h/d truck heads as they are on the short deck heads?
              Or is the mismatch covering 1/5th the port , making already smallish ports even smaller where the intake meets the heads.
              Are the heads intake mounting side even at the same angle? If so, why would G.M. make different castings for a 427 h/d truck and not just use the 454 short deck peanut port heads on them? You know bean counters and all. I most likely wrong but I'd think there is more different in the heads between the short deck block ones and the tall deck block used ones. Are the 427 h/d truck intake ports even smaller than the 454 peanut ports golf ball size?

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              • #8
                I know you need spacers for a short deck MOPAR (383, etc) intake on a tall deck (440, etc) block but no clue on a Chevy.

                Dan

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                • #9
                  spacers have to do with the block...not the heads.

                  the medium duty tall deck heads are indeed oval port, closed chamber. But they also have smaller valves than normal light duty heads.

                  Depending on what you want do do with the engine, the heads should work ok on a flat top 454 short block, with a mild cam, headers, etc.



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