Custom Cometic head gasket pics

Discussion in 'Small Block Mopar Engine' started by Duane, Nov 20, 2017.

  1. Duane

    Duane Well-Known Member

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    Consistent with my plan to feed coolant through the center side frost plug holes to improve cooling to the cylinders with side by side exhaust valves, I had Cometic gasket
    Make these custom Mls head gaskets that have enlarged and slightly relocated coolant holes on the lower four coolant passages.
    Note the two center coolant holes are changed from stock as well as one small added 1/8 inch hole over the normally closed 1 inch coolant hole.
    My block has the two large upper deck coolant holes restricted with a threaded pipe plug with a 1/8 hole. The 1/8 hole in the gasket is to match the restriction of the pipe plug equally on both side. This will force almost all the coolant to flow past the exhaust valves with the coolest water first flowing to the center two cylinders where the engine is hottest.
    Cometic allowed me to revise the placement of the holes many times to try and optimize the location before I gave them the go ahead to make the gasket to my liking.
    The price they charged me was $89 dollars each. These gaskets now have a custom part number with cometic under my name. So now anyone can buy them if you are interested.

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    • mbaird

      mbaird mbaird FABO Gold Member

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      Can you elaborate? I cant picture the entire mod....
       
    • Duane

      Duane Well-Known Member

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      I will be feeding the coolant output from a radiator mounted meziere
      Dual outlet electric water pump to the center frost plugs of the block
      The picture of my motor with a vacuum pump in front instead of a water pump. Water will not be fed into the front of the motor.
      When the coolant comes into the side of the block I want it to go up into the heads through the bottom 4 coolant holes that pass right over the exhaust valve. A stock head gasket has the two center cooling holes very restricted which is countering what I am trying to do. See pic of stock gasket.
      This mod is from a thread on Mopar chat by Sanborn and from the striker small block book. Sanborn used to punch the coolant holes larger, but that is much more difficult to do on an Mls gasket, so I had Cometic make the gaskets with the holes enlarged and relocated.

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      • famous bob

        famous bob mopar misfit

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        I did that on a 406 sbc, it doesn`t need that large of coolant lines. I did the rear crossover thing on it also. I thot about doing it to my 505" wedge , but haven`t really had the need for it so far.
         
      • nm9stheham

        nm9stheham Well-Known Member

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        Is this just for overall cooling, or to fight some particular issue? Does the coolant still exit the front of the heads?
         
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        • yellow rose

          yellow rose Doctor of Thinkology.

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          I dyno tested something similar with W-5 heads and didn't find anything. I eventually undid it all and just ran the lines from in between the exhaust ports back to the water crossover in the intake.
           
          Last edited: Nov 21, 2017
        • moper

          moper FABO Gold Member FABO Gold Member

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          Just thinking out loud here.... It seems to me, that if you wanted to get coolant past the exhaust valves faster, it would be best to plumb the rear crossovers and front crossovers into a manifold. The water flow would need to be reversed, so it comes out of the radiator, into the manifold, into the heads, and then you could pull either from the sides and front passages in the block's jackets, or just from the front to feed back into the radiator. I
          I'm not seeing an easier exit for that coolant you're feeding into the block jackets. I think you're going to have worse hot spots and problems. Again just thinking out loud.
           
        • nm9stheham

          nm9stheham Well-Known Member

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          Not arguing against this idea overall, but I can see most of the coolant taking the direct path to the outlet, which is past the the front 2 cylinders in the head. There is nothing that will force the coolant for flow to the back, and IMHO it will suffer from lower/starved flow as there is more flow restriction going that way simply due to the longer path. In fact, I would not be surprised if the coolant going through the #2 and #3 lower coolant holes would push back a bit towards the back and stall any flow coming up from lower hole #4. I am certain that is why the stock holes ARE restricted in the places pointed to by the arrows.
          I'd be putting some mild restrictions into the #1, 2, and 3 lower coolant holes in the block to attempt to equalize the flow up to all sections of the head.
           
        • Duane

          Duane Well-Known Member

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          The lines I am going to run are #16 an or 1 inch. That is the same diameter as stock and matches the same area as 4 1/2inch cooling holes.
          Although I did not mention it I am planning on running rear lines to the manifold
           
        • Duane

          Duane Well-Known Member

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          I forgot to mention that I do plan to run rear lines from the heads into the front manifold. The exit volume would be the same as stock but more equally distributed. Reverse cooling is a different plan altogether. It cools the heads first, but does not flow any more than the passages allow. I am not trying to cool the heads first. I am trying to increase the amount of coolant to the hottest area of the block which is between the two opposing exhaust valves on each side of the block first. The small passages in a stock gasket prevent this.
           
        • Duane

          Duane Well-Known Member

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          As said before, there will be generous coolant lines run from the back of the head to a manifold. The coolant should exit fairly equally front and rear. The coolant path length to the back of the block and heads
          Is the same. That's why the feed is to the middle frost plug.
          If you were still feeding the coolant to the front then I can see the center holes in the gaskets being restricted, as you would need to force the water to the back of the head. But the stock system does not force much water past the exhaust valves because it all goes to the back 1 inch hole in the back of the block and then up into the head and then to the front manifold.
          You also need to remember why there are two exhaust valves side by side. To operate a heat riser valve prior to fuel injection. No modern v8 engine have this valve layout anymore. Our small blocks were intentionally designed to run hotter in the center.
           
        • nm9stheham

          nm9stheham Well-Known Member

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          OK, sounds like you have thought out a solution to the flow distribution.

          Same question stands: What problem is being addressed with lowering the exhaust valve temps? Trying to lower detonation issues on the center cylinders?
           
        • yellow rose

          yellow rose Doctor of Thinkology.

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          If the specific output is high enough, you can get the material between the cylinder on the 3/5 and 4/6 to make it fail. Also, the valve job doesn't last as long on those cylinders, just from the heat.

          I've tried a lot but never found any power. Never really saw a difference in anything else either. We had a few other things to try, but I quit.
           
        • mbaird

          mbaird mbaird FABO Gold Member

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          Is this a drag car, circle track, road race or street app? I wouldnt think a drag car would have as much of an issue...
          And are there mods for head gaskets that can aid in head cooling?
           
        • Duane

          Duane Well-Known Member

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          The gentleman who I have copied this mod from was a circle track racer but he claims the benefits of this mod applies to all forms of racing engines. The thread is still posted on Mopar chat. Just search for oil and cooling mods by Sanborn. But the cooling through the side of the block is also recommended in the stroker small block book.
          It is recommended to improve the cooling system when adding big block cubes to a small block.
          I should have also pointed out that part of the reason I am doing this is I am using an early W2 cast iron head which is prone to cracking.
          A drag car although running for short duration concentrates most of the heat generation in the heads at the exhaust valves, particularly the two center exhaust valve and has far from even head cooling.
           
        • Duane

          Duane Well-Known Member

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          This thread is about a modified head gasket that I had made by Cometic to improve head cooling.
           
        • mbaird

          mbaird mbaird FABO Gold Member

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          I was thinking of a bit less extensive mod.
          I was sure if simple mods to the gasket alone would render any benefits.
           
        • famous bob

          famous bob mopar misfit

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          yeah, we (I) kind of screwed it up. I like the mods myself. I did it to a street n strip engine, it helped cooling , helped filling w/o air being trapped, made the plug color more uniform. I did tie the tapped in lines from the rear of the intake water passages to the spacer I built to go under the thermostat. I was running a stock type alum water pump tho, and drilled and tapped the holes between the center cylinders.
           
        • nm9stheham

          nm9stheham Well-Known Member

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          Thanks... makes sense to go to the effort with that particular issue on valuable heads.
           
        • Duane

          Duane Well-Known Member

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          Interesting that you saw more uniform plug colour. There are a couple of benefits that have been pointed out to me in this thread that I was not aware of. Longer valve job life and plug colour.
          Yes the small 1/8 inch hole drilled into the pipe plugs that are threaded into the block are to prevent an air lock. That is also why I had cometic add the small 1/8 hole in the gasket to match with the hole in the plug. I was very impressed with the help I received from Cometic gasket. It was my first time dealing with them and they really can make a custom gasket for very reasonable cost.
           
        • Krooser

          Krooser Reform School Graduate

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          RIP Charles Sanborn...
           
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          • yellow rose

            yellow rose Doctor of Thinkology.

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            When did that happen?
             
          • 75Sport

            75Sport Grandpa

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            Duane,
            Well thought out and executed plan. Very clean and well done. I wish I were as capable. Happy Thanksgiving to you all!
             
          • Krooser

            Krooser Reform School Graduate

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            July 2017 IIRC... his son posted on MOPARTS? Never even spoke with him but he had a vast knowledge of all things MOPAR.
             
          • Krooser

            Krooser Reform School Graduate

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