Better head

Slant 6 Engines

  1. plymouth1

    plymouth1 Well-Known Member

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    Is there a difference in heads to start for a performance build I have a 77 head with no spark plugs seals I believe first yr without and 81 block
     
  2. krazykuda

    krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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    There's no such thing as bad head.... :D
     
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    • Syleng1

      Syleng1 Karma is real and Life is short... FABO Gold Member

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      Again- what year and model are we talking about?
       
    • rklein383

      rklein383 Well-Known Member

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      slant 6???
       
    • nitro_rat

      nitro_rat FABO Gold Member FABO Gold Member

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      67 and down heads had a less efficient chamber design, 60-62 heads had looser control of the chamber placement in the casting except for the "special" or star casting mark heads intended for the aluminum block motors.

      All 63 and newer heads have the tighter chamber placement tolerances and will work on aluminum or iron block.

      All 68 and newer heads have the same chamber.

      Drool tube heads are a little lighter than the late style heads but are functionally identical.
       
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      • plymouth1

        plymouth1 Well-Known Member

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        Thanks
         
      • pishta

        pishta I know I'm right....

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        @slantsixdan Looser control of chamber placement? That's major: I'd love to see how they fixed that casting process or even how it became an issue as a manufacturing process student. That sounds unlike Chrysler who fitted different pistons to the same blocks to within .003 tolerances. IIRC the later heads had a better quench design for emissions too. Super early heads had no alternator bolt boss by the stat housing.
         
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        • nitro_rat

          nitro_rat FABO Gold Member FABO Gold Member

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        • MOPAROFFICIAL

          MOPAROFFICIAL FABO Gold Member FABO Gold Member

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          This.

          And the aluminum was cast thin around the the liners...and corrosion would cause the casting to delaminate from the liner and cause the head gasket to leak.
          Many suffer from this. With the casting eroded away at the top...there is only the sleeve/liner top edge to seal the gasket.
          The head gasket is a copper and composite type material, greenish. Its form fit tight around the cylinders, water passages..for a reason I'm sure like maybe to deflect direct pressure in the cooling system away from the key sealing points. I have a full set, maybe I'll pull it out and take a pic of the head gasket. Think I paid 160.00 for it off ebay about 18yrs ago or so. Bought the entire car AL 225 v 200 '62 for 700.00. I drove into the wrecking yard where it was parked for 30 something years.. an old lady who knew Jerry traded it in for a more reliable car in the 80's. She said it had started overheating. I pulled it apart, stock, head gasket was weeping. Everything was cherry otherwise.
           
        • nitro_rat

          nitro_rat FABO Gold Member FABO Gold Member

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          I'm working on an aluminum motor also, mine has plenty if sediment in the bottom of the water jackets but the tops of the cylinders are nice. I haven't gotten into it far enough to determine if it's rebuildable or not but so far it's promising...
           
        • MOPAROFFICIAL

          MOPAROFFICIAL FABO Gold Member FABO Gold Member

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          If the top of the cyl could be built up, welded without warping the shit out of it...it would cure the weeping issue most have around 60-70k miles.
          Dutra did the flange deal...that was expensive and them he blew up the bottom end using the cast crank and he might have done something else with the oil squirt holes pointing in the wrong direction. Cant remember.
          But welding or filling the block top half and or limiting the coolant flow in the process to just the exhaust side of the cylinders with wax and some copper pipe for passage direction to head.... I was thinking a lot about it 12 yrs ago before I did the stroker stuff.
           
        • nitro_rat

          nitro_rat FABO Gold Member FABO Gold Member

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          Doctor Doug omitted the "squirters" altogether on "Twiggy." Used some aftermarket rods IIRC for a non-/6 application. Funny thing about bearings is - no oil out = no oil in! I predicted the end result as I was reading the thread and was unsurprised when poor Twiggy tossed a rod through the block in protest on the freeway...

          The aluminum blocks don't take kindly to welding from what I've read. I know one of DD's aluminum builds had a welded closed deck and massive warpage issues. Another had the top deck closed with hard block. Both engines were short lived after the good Doctor's "treatments."
           
        • MOPAROFFICIAL

          MOPAROFFICIAL FABO Gold Member FABO Gold Member

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          Welding the entire deck is a lot more heat then one cyl top at a time. Submerge the block to the last inch and lay a bead around the top outer edge, slowly a little at a time. Old doug seems to make the oiling go away on slant 6 motors when things do go wrong, seems the common denominator.
           
        • RustyRatRod

          RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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          You've really gotta hand it to him though. While he's had some failures, he's had some good builds, too. He's not afraid to try things. Gotta love it.
           
        • nitro_rat

          nitro_rat FABO Gold Member FABO Gold Member

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          Many lessons to be learned from watching his work for sure...
           
        • Lord Sparky

          Lord Sparky Well-Known Member

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          As my mom used to say, “It’s all in the suction.”
           
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          • Hyper_pak

            Hyper_pak Old School Chrysler Fan

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            The head without spark plug tubes has hardened seats. Or did, depending on how much use it has seen. So if the head is in good shape that head would be good for a daily driver. But it is a heavy head, adds 5-10 lbs to total engine weight.
             
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            • pishta

              pishta I know I'm right....

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              Money shot:
              "Later, a five-pointed star was used to denote the special head for use with the aluminum block, which had slightly smaller combustion chambers and tighter control of combustion
              [​IMG]
              chamber placement to assure proper head gasket sealing. This was necessary due to the relatively narrow area available at the top of each cylinder liner for gasket sealing. For the 1963 model year, the tighter placement control and smaller chamber diameter were communized on all Slant-6 heads; any '63 or later cylinder head can be used on an aluminum 225.."
              Hard to believe a head combustion chamber could be 'moved' in an existing casting but it sounded like it was a new casting altogether with a smaller CC area to completely cover the cylinder edge, not an old casting with a potentially larger CC footprint. Interesting...kinda sounded like a sketchy design from the start with that small of a fire ring area.
               
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              • nitro_rat

                nitro_rat FABO Gold Member FABO Gold Member

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                My understanding is that the placement of the cores was more carefully controlled. The only early casting that I have to compare is a "star" head.
                 
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