Help I D small block heads.

Small Block Mopar Engine

  1. RAT ROD AL

    RAT ROD AL FABO Gold Member FABO Gold Member

    Messages:
    1,358
    Likes Received:
    1175
    Joined:
    Jan 18, 2013
    Location:
    St. James City. FL.
    Local Time:
    7:26 PM
    I have a pair of small block heads that I got a few years back. Had run them through the machine shop, Had 2.02 valves installed, guides ect. Just wondering how good of a head they are for just a street car. I see 360 cast in the runners under the valve covers along with ( best I can make out) is 3418915 on both . Any help would be appreciated, Thanks AL
     
    • Agree Agree x 1
    • Mtrhead

      Mtrhead Ace of Spades ♠️

      Messages:
      1,156
      Likes Received:
      281
      Joined:
      Sep 19, 2018
      Location:
      S.C.
      Local Time:
      7:26 PM
      It's a J head very desirable 340/360 head
       
      • Thanks! Thanks! x 1
      • Agree Agree x 1
      • Alaskan_TA

        Alaskan_TA Well-Known Member

        Messages:
        4,498
        Likes Received:
        2343
        Joined:
        Nov 12, 2004
        Location:
        PA
        Local Time:
        7:26 PM
        Ignore the letter.

        915 heads can have J, O, U or Z letters but they are all 915 castings.

        On 340s, 2.02 intakes, smaller on 360s.

        Some were also used on the AARs & T/As with offset intake push rod holes.
         
        • Like Like x 1
        • Thanks! Thanks! x 1
        • RAT ROD AL

          RAT ROD AL FABO Gold Member FABO Gold Member

          Messages:
          1,358
          Likes Received:
          1175
          Joined:
          Jan 18, 2013
          Location:
          St. James City. FL.
          Local Time:
          7:26 PM
          I've seen X and J cast in other heads by the spark plug hole ,but don't see any on these. Thanks for the info guys
           
        • Locomotion

          Locomotion Well-Known Member

          Messages:
          2,750
          Likes Received:
          291
          Joined:
          May 31, 2004
          Location:
          Florida
          Local Time:
          7:26 PM
          X heads were only 894 heads. The 915 heads were the original 360 heads, but also used on 340's starting in 1970, but machined according to application/year.

          Only bad thing about 2.02" heads is that you don't know how many valve jobs they've already had. That sinks the valve & seats and reduces flow. Taking the same 915 head with 1.88" intakes and machining them for 2.02" will provide a nice, fresh, high seat and can be made more consistent through them all.
           
          • Like Like x 1
          • Thanks! Thanks! x 1
          • Agree Agree x 1
          1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
            By continuing to use this site, you are consenting to our use of cookies.