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    #16
    ........................
    Originally posted by Hubcap View Post
    Rick, the slop is side to side not up and down.
    OK..... that is not good! The upper bushing is worn out, and the lower bushing will follow shortly.
    You can have it re-bushed if you want to.



    Because of this the points gap keeps fluctuating and causing the rotor to not run evenly throughout the cap, hence causing the extra marks on the 3 posts.
    Understood!

    I do know how to set the correct points gap manually, once engine is running I will check again via dwell.
    No need to with the upper shaft bushing gone.

    I have found a used dist in Detroit, should be here by Tuesday, will install and advise.
    This must be a Marine unit, and offer the correct progressive and total advance for your SBC Marine engine.

    Since you have twin engines, I would replace both ignition distributors with identical units.
    The YLM 624 AV is a good unit if you can find them


    Image result for YLM624AV





    .https://www.jegs.com/webapp/wcs/stor...&storeId=10001




    Adjust the ignition timing the same on each engine.



    WARNING: DO NOT allow any metallic item to bridge the gap between the reluctor and the sensor.
    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

    Comment


      #17
      Well...
      Still no success, although i do have proper dwell now.

      Could the timing chain have slipped?

      How does one check to see if this is the case without having to remove the front engine parts?

      Any help appreciated, getting desperate now.

      Thanks

      Comment


        #18
        I initially brought up the possibility of a jumped chain based on the age of your engines. I’ve replaced a few sbc chains that had jumped. Engine ran fine when shut down then wouldn’t start, usually cranking just fine and acting like it might fire.

        With the plugs removed do a cylinder compression test and take note what the numbers are. If they’re all substantially low I’d suspect the chain. You can use a crank wrench to roll the crank back and forth while watching the distributors rotor, if it takes a bit of crank movement in the opposite direction before you see the rotor react that’d be an indication of the amount of slop that’s in the chain.
        Dave
        Edmonds, WA
        "THE FIX"
        '93 2556
        Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
        Misc. projects thread
        https://www.baylinerownersclub.org/f...56-gctid789773

        Comment


          #19
          Dave
          Thanks, I did compression check on nbr 1 only it was 155psi. I will do them all tomorrow but since nbr one is at 155 wouldn't that indicate things are good?

          Comment


            #20
            Originally posted by Hubcap View Post
            Dave
            Thanks, I did compression check on nbr 1 only it was 155psi. I will do them all tomorrow but since nbr one is at 155 wouldn't that indicate things are good?
            Nope, common to only have one or two bad cylinders. As Dave suggested verify the timing chain didn’t jump by setting the crank at TDC and the rotor pointing to plug terminal one on the distributor cap, then verify both valves are fully closed.

            1997 Maxum 2400 SCR 5.7LX Bravo II

            Mike

            Comment


              #21
              I would think that If you put the no1 piston at TDC then backed it off the number of degrees equal to the set timing value the distributor rotor should line up exactly with the no 1 plug wire. If this is not the case the timing chain has most likely slipped.
              Jim Gandee
              1989 3888
              Hino 175's
              Fire Escape
              [email protected]
              Alamitos Bay, SoCal

              Comment


                #22
                Is it possible the neutral safety switch could be affecting the starting even though the engine is turning over normally?
                Does it by chance act similar to a kill switch by grounding the ignition out?

                Comment


                  #23
                  Originally posted by Hubcap View Post
                  Is it possible the neutral safety switch could be affecting the starting even though the engine is turning over normally?
                  Does it by chance act similar to a kill switch by grounding the ignition out?
                  No, the neutral safety switch circuit when in the open position (not fully engaged in neutral) will not allow the engine to crank. An open kill switch circuit however will “kill” power to the ignition system. A jumper wire directly from DC positive to the coil positive terminal would bypass a faulty kill switch, but I think you tried that already.
                  Dave
                  Edmonds, WA
                  "THE FIX"
                  '93 2556
                  Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                  The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                  Misc. projects thread
                  https://www.baylinerownersclub.org/f...56-gctid789773

                  Comment


                    #24
                    Based on your findings regarding the distributor shaft play and chewed up cap/rotor issue I think you should investigate the possibility of an ignition issue further. Have you verified a good snap/spark at the plugs?
                    Dave
                    Edmonds, WA
                    "THE FIX"
                    '93 2556
                    Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                    The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                    Misc. projects thread
                    https://www.baylinerownersclub.org/f...56-gctid789773

                    Comment


                      #25
                      ......................
                      Originally posted by Hubcap View Post
                      Well...



                      Still no success, although i do have proper dwell now.
                      What did you do about the distributor shaft side play that you mentioned earlier?
                      What dwell angle did you use?


                      Could the timing chain have slipped?
                      It would be very rare for this to have occurred.

                      How does one check to see if this is the case without having to remove the front engine parts?
                      See Dave's response below.
                      Originally posted by Dave
                      You can use a crank wrench to roll the crank back and forth while watching the distributors rotor, if it takes a bit of crank movement in the opposite direction before you see the rotor react that’d be an indication of the amount of slop that’s in the chain.

                      Originally posted by Hubcap View Post
                      I did compression check on nbr 1 only it was 155 psi. I will do them all tomorrow but since # one is at 155 wouldn't that indicate things are good?
                      155 psi is within a good range for this engine.
                      If all cylinders are within 10% of the highest cylinder pressure reading (what ever that reading might be), all would be within a safe range.


                      Side note:
                      Ideally we want the rotor to be aiming towards the #1 cylinder while #1 is at TDC on the C/S.
                      However, as long as the spark plug cables are indexed correctly within the cap, and are following the firing order, this is not critical......... the engine will operate just fine!



                      Originally posted by Hubcap
                      Is it possible the neutral safety switch could be affecting the starting even though the engine is turning over normally?
                      Unlikely. The Neutral Safety switch (while not in neutral) interrupts the starter motor's S circuit ONLY.

                      Does it by chance act similar to a kill switch by grounding the ignition out?
                      A lanyard style kill switch (when the lanyard clip is pulled from the switch) interrupts the Ignition circuit only.
                      It does not take the circuit to Negative!


                      NOTE: if your alternator field circuit is supplied by the ignition circuit, you could undergo alternator damage if a kill switch clip was pulled while running.
                      (it's unlikely that your AQ225 is equipped with a lanyard style kill switch as per the above)


                      If a timing chain was to jump one tooth at either sprocket, it would equate to a 10* change at the camshaft.
                      (360 degrees divided by 36 = 10)

                      Keep in mind that all indexing (cam, piston TDC, etc) is done in terms of crankshaft angle.


                      Since ignition advance relates to crankshaft angle, and is adjusted in crankshaft degrees, the ignition advance would NOT also be off by 10* .

                      Click image for larger version  Name:	SBC timing chain and sprockets.jpg Views:	0 Size:	63.9 KB ID:	554290




                      Originally posted by Dave
                      Based on your findings regarding the distributor shaft play and chewed up cap/rotor issue I think you should investigate the possibility of an ignition issue further. Have you verified a good snap/spark at the plugs?
                      I agree 100%.

                      Excessive side play (within the distributor shaft) will prevent you from setting the correct dwell angle.
                      Once up and running, the dwell angle will be erratic.

                      You should be seeing a white or bluish/white spark, and should be able to hear is snap.




                      .
                      Rick E. Gresham, Oregon
                      2850 Bounty Sedan Flybridge model
                      Twin 280 HP 5.7's w/ Closed Cooling
                      Volvo Penta DuoProp Drives
                      Kohler 4 CZ Gen Set

                      Comment


                        #26
                        Since ignition advance relates to crankshaft angle, and is adjusted in crankshaft degrees, the ignition advance would NOT also be off by 10* .

                        Rick, I barely know what a piston is but since the distributor is driven by the cam wouldn’t the timing therefore be off if the timing chain slipped one tooth? Maybe I’m misunderstanding your comment?
                        Jim Gandee
                        1989 3888
                        Hino 175's
                        Fire Escape
                        [email protected]
                        Alamitos Bay, SoCal

                        Comment


                          #27
                          Originally posted by 2850Bounty View Post
                          ......................

                          If a timing chain was to jump one tooth at either sprocket, it would equate to a 10* change at the camshaft.
                          (360 degrees divided by 36 = 10)

                          Keep in mind that all indexing (cam, piston TDC, etc) is done in terms of crankshaft angle.


                          [COLOR=#0000FF]Since ignition advance relates to crankshaft angle, and is adjusted in crankshaft degrees, the ignition advance would NOT also be off by 10* .

                          .
                          Rick, if the chain jumped one tooth at the crank sprocket (18 toothed sprocket) would that not cause a 20 degree valve timming discrepancy?
                          Im also wondering about the ignition advance statement. The ignition timing being related to crankshaft angle if in fact the chain jumped the ignition timing would follow the camshaft and also have a 20 degree discrepancy. Yes?🤔
                          Dave
                          Edmonds, WA
                          "THE FIX"
                          '93 2556
                          Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                          The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                          Misc. projects thread
                          https://www.baylinerownersclub.org/f...56-gctid789773

                          Comment


                            #28

                            Originally posted by Rick
                            Since ignition advance relates to crankshaft angle, and is adjusted in crankshaft degrees, the ignition advance would NOT also be off by 10* .
                            Originally posted by Jim_Gandee View Post

                            Rick, I barely know what a piston is but since the distributor is driven by the cam wouldn’t the timing therefore be off if the timing chain slipped one tooth? Maybe I’m misunderstanding your comment?
                            Well, good question Jim, and it would require me to give a two part answer/explanation.

                            1.... if the chain jumped one sprocket tooth, and if the ignition advance had been adjusted after that occurred, then the answer would be NO..... the timing would or could still be spot on.

                            2....if the chain jumped one sprocket tooth, and if nothing since then had been done to the ignition advance, then yes.... the ignition advance would also be OFF to the tune of 20 crankshaft degrees.

                            We all know that an engine would not run if the ignition advance was off by 20 crankshaft degrees.
                            It would not start up on 18*, and it would detonate on 38* @ 3k rpm.





                            Rick E. Gresham, Oregon
                            2850 Bounty Sedan Flybridge model
                            Twin 280 HP 5.7's w/ Closed Cooling
                            Volvo Penta DuoProp Drives
                            Kohler 4 CZ Gen Set

                            Comment


                              #29
                              Originally posted by builderdude View Post

                              Rick, if the chain jumped one tooth at the crank sprocket (18 toothed sprocket) would that not cause a 20 degree valve timming discrepancy?
                              Im also wondering about the ignition advance statement. The ignition timing being related to crankshaft angle if in fact the chain jumped the ignition timing would follow the camshaft and also have a 20 degree discrepancy. Yes?🤔
                              Yes... and also see my post #28 and my comment regarding how the spark timing would cause an engine to run (actually NOT run) if this occurred.
                              This is where is gets difficult to explain and let alone understand. I even question myself every time I try to explain this!

                              Keep in mind that the crankshaft and camshaft have a 2 to 1 relationship....... 2 Xs crankshaft per 1 Xs cam.


                              ..... if the chain jumped one crankshaft sprocket tooth, it would cause a 20* change to the position and location of the chain.
                              (360 divided by 18 = 20)
                              In other words, the camshaft chain sprocket would either lag behind, or lead the crankshaft by 20*

                              ..... if the chain jumped one camshaft sprocket tooth, it would cause a 10* change to the position and location of the chain.
                              (360 divided by 36 = 10)
                              In other words, and with the 2:1 ratio, the crankshaft chain sprocket would cause the camshaft to either lag behind, or lead the crankshaft by that same 20*.

                              If I'm mistaken, please point it out. I'm old and my mind is not what it used to be. And no making fun of me!!!!



                              Click image for larger version  Name:	SBC timing chain and sprockets.jpg Views:	1 Size:	87.7 KB ID:	554332
                              Rick E. Gresham, Oregon
                              2850 Bounty Sedan Flybridge model
                              Twin 280 HP 5.7's w/ Closed Cooling
                              Volvo Penta DuoProp Drives
                              Kohler 4 CZ Gen Set

                              Comment


                              • builderdude
                                builderdude commented
                                Editing a comment
                                Oh man, Gonna be in my head all day now 😆

                              #30
                              Rick, the way my brain works (and I'm not saying it works very good) I would physically and visually have to do it to an engine on a stand to confirm 🤔
                              Just for kicks I found these pics of old timing set vs aftermarket timing set. 22 toothed crank sprocket on my aftermarket set.


                              Click image for larger version

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ID:	554340Click image for larger version

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Views:	79
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ID:	554339
                              Dave
                              Edmonds, WA
                              "THE FIX"
                              '93 2556
                              Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                              The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                              Misc. projects thread
                              https://www.baylinerownersclub.org/f...56-gctid789773

                              Comment

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