318 head porting for the average joe

Small Block Mopar Engine

  1. Abodybomber

    Abodybomber Breaking street machines , since 1983.....:) Legendary Member

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    Nice trap speed...
     
  2. 4spdragtop

    4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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    So X head stripped. Proceed with the same theory as Justin and others posted here?
    As i mentioned I did my 1st port job on 273 heads a couple summers back. I know not to get greedy, but are water jackets in same place? Any differences in x heads?
    Thanks

    20180310_133623.jpg
     
  3. Cudafever

    Cudafever Well-Known Member

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    If your going to be grinding on them head enough to worry about finding water......You need to start with a better head.

    With that said, here are some pictures. NOTE: THESE ARE 340/360 HEAD, NOT 318'S

    2009_1015Image0010.JPG 2009_1015Image0020.JPG 2010_0221596MoparHead0004 (1).JPG
     
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    • Dk1985

      Dk1985 Member

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      B2259107-95E8-4FB3-98C4-B3ACDE2E9CE9.jpeg Current progress
       
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      • Michael Harrington

        Michael Harrington Active Member

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        I did some J heads for a future 360. Proceeding with caution I removed only enough material to have smooth slaggy/parting line free surfaces. (No hogging out attempts at 351 Cleveland sized ports) I polished the combustion chambers, exh bowls and exh ports much more than needed simply because I could and was actually having fun. They look like sterling silver. The intake bowl was blended (machinists cutter enlarged valve to a 2.02) Intake side was gasket matched and the pushrod pinch? I didnt measure but just removed a little bit of wall thickness. Intake ports and bowls final finish was with a coarse sandpaper cartridge rolls. The guides I maintained caution. Steve Dulcich achieved incredible numbers porting J heads but man it he removed alot of the Int valve guide structure.Hes ported tons of mopar heads and flows them- I didnt try to duplicate his valve guide work. I left the guides srtuctural length but rounded and contoured every square edge. There are very swoopy and impressive (To me). As some just stated- this is hot rodding when we DIY. IMAG0493.jpg IMAG0495.jpg IMAG0493.jpg IMAG0495.jpg

        IMAG0496.jpg
         
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        • STRorange

          STRorange Well-Known Member

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          Nice work Michael!
          We have had 'J' head issues with them going thin as per the cut head inside the intake port too.
          'J' heads are brilliant and don't need to be 'HOGGED' they is good to start with!
          STR
           
        • STRorange

          STRorange Well-Known Member

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          What happened to the 'crazyguy'?
          Everyone deserves a second chance and his porting info was 'top-drawer' work indeed...
          As its Easter, maybe he can rise from the grave?

          STR
           
        • Michael Harrington

          Michael Harrington Active Member

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          Thanks ST. I had fun doing these with my 3/4 HP flex shaft Dremel.
           
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          • Dk1985

            Dk1985 Member

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            CD14E0B0-5AB4-4FA8-91E9-3695FE8CD817.jpeg
             
          • Dk1985

            Dk1985 Member

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            I’ve git the bowls cleaned up pretty good. I’ve scribed a 318 size gasket on the intake port. I think it’s 1.05” wide. My intake manifold is also that size. I can’t enlarge the port that much without breaking into the pushrod tube. If I leave it, it would be a pretty big mismatch. Not sure how to proceed
             
          • 4spdragtop

            4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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            I'm a newbie to this,(did a set of 273, now doing a set of 340 x heads), but can't you just "lean" or taper the port back to your scribe line?
            Looks good!
             
          • STRorange

            STRorange Well-Known Member

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            [​IMG] Hi DK,
            I would grind the port inlet at an angle to meet up with thinnest point, inside the port entrance.
            To get the port as wide as poss. you will need to buy or make an 'E' gauge.
            I made my own with some 1/4 inch steel rod and a hobby welder.
            The hardest part was making a swivel joint and I cut down an airline fitting with a 1/4 bore for this.
             
          • Cudafever

            Cudafever Well-Known Member

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            pic didn't show
             
          • Dk1985

            Dk1985 Member

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            At what point can I justify enlarging that bulge area? They are about .750 at the widest point. I also thought about just grinding until I broke though and sleeving them with a brass tube.
            Are there gains to be had enlarging this pinch area with just mild bowl work?
             
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            • Cudafever

              Cudafever Well-Known Member

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              simple answer is NO.
              Pushrod pinch(prp) is not as big of a restriction as it look. If your working on the short side radius (SSR), raising the roof, at the ssr and raising the roof at the intake/ head surface. THEN, the Pushrod pinch becomes a restriction. If you don't have a flow bench and can watch what happes, Don't Do It! If your not going to mess with the ssr, the prp, is NOT the smallest Cross Section in the head. there for, no cfm gain grinding on it.
              Clean it up and leave it alone is my suggestion.........
               
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              • Dk1985

                Dk1985 Member

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              • Dk1985

                Dk1985 Member

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                I did smooth the ssr a bit. I’ll try and post some pictures tonight
                 
              • Cudafever

                Cudafever Well-Known Member

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                3 angle Valve Job and blend in the bottom cut in the bowl will give you the biggest jump in cfm and the least amount off work. From that point on, time becomes a premium and cfm gain is small.
                 
              • Cudafever

                Cudafever Well-Known Member

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                looking forward to it.
                 
              • Dk1985

                Dk1985 Member

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                896A6532-7036-4454-933A-28E1B98D4CD3.jpeg

                8708B070-D185-46EF-9160-FAA1144CEA30.jpeg
                 
              • Dk1985

                Dk1985 Member

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                Hard to take a good picture. I’m using a 1.88 intake valve
                 
              • Cudafever

                Cudafever Well-Known Member

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                The SSR is a vary finicky part of the port, without a flow bench you can't tell if your gaining or killing the port. That first pic, looks like you heading down that road.
                Like a said before a 3 angle valve job and a good bowl blend does wonder on a stock head. Other then cleaning up the casting, i wouldn't go any farther.
                One of my heads i worked that SSR and opened it up, widend it up and the flow when Down! and made horrible screeching sounds. stuck my velocity probe in the port and found vary High air speeds in the middle and a negative pressure at the PRP wall at the ssr.
                In other word the the air was going over the ssr and my bad porting(I thought it looked GRATE!!) caused a low pressure that force the air back up the port. Them heads would have made less HP then a stock unmolested head.........Even though they would have flowed more air on the flow bench then a stock head.

                Just be careful, it's Real Easy to get Greedy and shoot yourself in the foot. :thumbsup:
                 
              • Dk1985

                Dk1985 Member

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                Thanks everyone for the help
                 
              • pishta

                pishta I know I'm right....

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                question: If the short side radius and valve blend is so easy to do , why did Mopar not cast this into the heads from day one? C'mon, you cant tell me in the HP race of the late 60's that Chrysler didnt see this garbage as low hanging fruit for an easy casting fix? Its funny to see basic porting add 50HP and not have it realized by Mopar. Do these porting steps kill real world street RPM torque?
                 
              • BigBlockMopar

                BigBlockMopar BigBlockMember

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                They could have backcut the intake valves too for some more lowlift flow.
                But maybe that would have been another machining job that would've cost big money.
                 
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