Cyl Head info needed !!!

Small Block Mopar Engine

  1. 1Badcolt

    1Badcolt Well-Known Member

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    Ok so just tonight I finally pulled valve covers to see what cyl heads my 340 has on it and I found the following casting numbers # 3418915
    I also saw 360 on other end of each cyl head so I assume after looking online I have
    1971 360 heads .
    do these particular heads have performance potential and if so how much with serious porting etc
    thanks Chris .
     
  2. rumblefish360

    rumblefish360 So close, yet so far away

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    Most heads have that “360” cast into it but that doesn’t mean there “360” heads.

    WHat valve sizes?
     
  3. 1Badcolt

    1Badcolt Well-Known Member

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    Ok not sure just looked tonight
     
  4. perfacar

    perfacar Well-Known Member

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    if you have a 1971 340, it will have 2.02 int valves
     
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    • 1Badcolt

      1Badcolt Well-Known Member

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      I guess I want know valve size until I pull the heads and measure them
      Im fixing to sale the 340 minus intake and heads and exh manifolds so I will get info asap.
       
    • rumblefish360

      rumblefish360 So close, yet so far away

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      And make sure there the OE 2.02 valves!
       
    • 1Badcolt

      1Badcolt Well-Known Member

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      I do have a 70
      340 I ran the numbers last week.
       
    • rumblefish360

      rumblefish360 So close, yet so far away

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      Which means what for the heads in question?
      I’m missing wht your statement means.
       
    • 1Badcolt

      1Badcolt Well-Known Member

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      This is my casting number for the block
      Im assuming with numbers I listed I have a set of 71
      360 heads on my engine ?

      Screenshot_2019-02-06-00-15-51.png
       
    • rumblefish360

      rumblefish360 So close, yet so far away

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      Assume, key word and mistake.

      BRB, looking into a book....
       
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      • 1Badcolt

        1Badcolt Well-Known Member

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        My 340 is a 1970 model according to casting # on the block !
         
      • 1Badcolt

        1Badcolt Well-Known Member

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        Going to unload the 340 but keeping cyl heads
        Intake
        Exh manifolds .

        20190204_194449.jpg
         
      • krazykuda

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

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        They started using the 915 heads on the 340 in mid year 1970...
         
      • rumblefish360

        rumblefish360 So close, yet so far away

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        Easier than typing

        image.jpg
         
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        • 1Badcolt

          1Badcolt Well-Known Member

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          Ok thank you Sir
          They could be original to motor then ###
          I was told and again undocumented
          That entire driveline came from a 70 Duster .
           
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          • 1Badcolt

            1Badcolt Well-Known Member

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          • 1Badcolt

            1Badcolt Well-Known Member

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            Ten 4

            20190204_205543.jpg
             
          • brian6pac

            brian6pac Well-Known Member

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            look at the vin # on the block and the date code It might be out of a 71 car, also what is the date on the heads
             
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            • furrystump

              furrystump Well-Known Member

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              Without moving the pushrod pinch you can get about 280 cfm out of an X head. A touch less with the other castings. Unless you are tied to that casting there are more economical choices out there.
               
            • 1Badcolt

              1Badcolt Well-Known Member

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              I will get info tonight
              Maybe the heads are original ???
              Hopefully they are 2.02 that would be nice
               
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              • 1Badcolt

                1Badcolt Well-Known Member

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                Yes sir thank you !!
                I have some decent alum heads to use but was just considering keeping these since they are getting kinda hard to find .
                 
              • furrystump

                furrystump Well-Known Member

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                Unless you are forced to run them by class rules or just really like the idea of running a stock casting it will never be worth putting the $’s into them to get to that level. I view the money I spent on porting my x heads as money very well spent. That being said I wouldn’t even think about an X head if I wasn’t forced to run it. Think of what you could do with $2800-$3000 and a better casting or clean sheet of paper?
                 
              • toolmanmike

                toolmanmike FABO Staff Staff Member FABO Gold Member

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                #3418915 is a 71-72 340-360 head open chamber with 1.88/1.60 valves. Cast mark "J".
                 
              • 1Badcolt

                1Badcolt Well-Known Member

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                Yes sir good point !!
                The only limitations imposed on cyl heads is stock valve angle and no off set rockers allowed .
                 
              • brian6pac

                brian6pac Well-Known Member

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                Not really, 68 69 were X heads 894 castings, 70 - 72 J heads 915, 70 & 71 340 had 915 2.02 1.60, 71-up 360 had 915 1.88 1.60, 72 340 had 1.88 1.60, 73 340 587 heads. I have seen chats that say different but over the years I have collected and sold many sets of heads off of 340's and this is what I have seen.
                 
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