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283 dilemma

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  • Dave #34924

    283 dilemma

    When taking my engine out I notice 2 adjacent plugs had very small gaps as if they had been hit, that was 3 years ago, now when I had the heads cleaned up and inspected, the machinist told me I had 2 slightly bent exhaust valves.. also adjacent, in both cases I dont know which ones, the gaskets i will use are felpros and they are .020 thicker than the steel gaskets that were on there.
    My engine is a 283 from 1959 or 1960, the heads are from 58-61, part #3748770 and they say X-58 on 1 side, I believe these to be 58 power pack heads 64cc. The pistons in the engine say .040 on them and they are pop ups and the spark plugs were AC R44s...do I have the right plugs in the engine,if I do could i space them up a little, I also noticed small gouges on the outer portion of each of the piston tops as if something had been hitting at one time. Any guess what the compression ratio might be...and believe it or not, the engine ran good.
    My plan is to clean it all up, timing chain, rear main seal, all new gaskets, paint and do up the whole engine bay,...put the motor back in for a few years and then do the whole drivetrain over to a streetrod
  • Verle R.
    Extremely Frequent Poster
    • March 1, 1989
    • 1163

    #2
    Re: 283 dilemma

    Dave,

    It sounds like the piston domes are hitting the spark plugs. This was common with extended timp plugs (the S in the R44S indicates extended tip) and pistons with domes.

    The threads on plugs and in heads are indexed different. Years ago we would check how the plugs fit each hole and make sure the ground electrode (the upper part) was turned any direction but down toward the piston. With extended tip plugs the clearances are small with piston at top dead center.

    The bent exhaust valves are possibly due to weak valve springs. With an engine that old it would be a good idea to replace all valve springs.

    Verle

    Comment

    • Dave #34924

      #3
      Re: 283 dilemma

      R44's are not available anymore, I will have to go with R45's, what should i expect from the performance.
      The machinist replaced the 2 valves and he tested the springs and said they were good, hmmmmmmmmmmm.

      Comment

      • William C.
        NCRS Past President
        • May 31, 1975
        • 6037

        #4
        Re: 283 dilemma

        In general use, there will be no performance difference between the 44 and 45 plugs.
        Bill Clupper #618

        Comment

        • Dave #34924

          #5
          Re: 283 dilemma

          How about to hot or cold? Fouling? etc, etc....

          Comment

          • Lonnie Johnson

            #6
            Re: 283 dilemma

            Dave,
            The problem with the "testing" that your mechanic completed, is that it was probably a simple static tension test. With the dynamics involved in an engine operating up to, and possibly beyond the 5,000rpm range, the spring recovery rate from a compressed situation is not what it was when new. The recommendation to replace the springs is an excellent one, and I would also advise you do so. Bent valves are not a fun experience, don't ask how I know!
            Lonnie Johnson

            Comment

            • William C.
              NCRS Past President
              • May 31, 1975
              • 6037

              #7
              Re: 283 dilemma

              45 is "hotter" than a 44, and less prone to fouling. It's a great choice for a "Cruiser"
              Bill Clupper #618

              Comment

              • Roy B.
                Expired
                • February 1, 1975
                • 7044

                #8
                Re: 283 dilemma

                Having pop up pistons increases the distance to the spark plug ,so that any CARBON build up on top of the piston will increase the distance causing the TWO plugs you mentioned to close AND bend the valves .Use a hotter plug and now and then run water down the Carb to make sure there won't be any carbon build up

                Comment

                • Andy #28359

                  #9
                  Maybe the problem was Detonation *NM*

                  Comment

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