Help I D small block heads.

Discussion in 'Small Block Mopar Engine' started by RAT ROD AL, Jan 11, 2019.

  1. RAT ROD AL

    RAT ROD AL FABO Gold Member FABO Gold Member

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    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
     
  2. Mtrhead

    Mtrhead Well-Known Member

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    It's a J head very desirable 340/360 head
     
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    • Alaskan_TA

      Alaskan_TA Well-Known Member

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      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.
       
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      • RAT ROD AL

        RAT ROD AL FABO Gold Member FABO Gold Member

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        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

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        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.
         
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