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  • Setting initial timing

    Hello everyone,
    I am having a weird problem while setting base timing on my 5.7 penta (the engine is a Frankenstein replacement engine, so, I cannot even tell the actual model number). The distributor is a Delco-style aftermarket replacement. As I understand it, I should see timing advancing 9 deg once the "shunt" is removed. It does not. I see no changes when connecting/disconnecting the shunt. I can tell that the shunt works since it does stop advancement at higher RPMs, i.e. timing stays the same throughout the full rpm range when shunt is connected. I also see timing advancing 7 deg (from initial 12) at 3000rpm when shunt is removed. So, it sort of works, except I see no advancement from initial 12 deg to target 21 at 600 rpm. So my total advancement is only 19. I went through 3 different modules, all do the same thing. Any ideas?

  • #2
    Do you start the engine and then put the shunt on? That includes plugging it in and providing 12V. That is the correct procedure.

    While we are talking about the procedure, describe what you do.
    1998 Wellcraft Eclipse 24 Cuddy
    Volvo Penta Duo-Prop 7.4L "LK"

    2006 Sun Tracker Party Barge 21
    Mercury 90 4-Stroke FI
    "Common sense is not very common"
    "Failing to prepare is preparing to fail." -- John Wooden

    Comment


    • #3
      Hi Bruce, Thanks for your response. I believe I did follow the "correct" procedure, i.e. plug in the shunt, start the engine, connect the black wire from the shunt to B+ (12V). I believe I should be seeing timing change the moment I connect/disconnect the shunt from B+. In my case nothing happens, I see no change in timing (as verified by the light) and no change in rpm. My engine has no injection and no computer, the 4-prong connector on the ignition module is normally not plugged to anything, i.e. the ignition module is the only thing that controls the ignition advancement. It would be tempting to conclude that the ignition module is faulty, however, at least two other different modules do the same thing. I also know that the shunt works since the ignition advancement does stop when the shunt is connected.

      Comment


      • #4
        You start the engine...THEN plug in the shunt and connect the 12V. Try that.
        1998 Wellcraft Eclipse 24 Cuddy
        Volvo Penta Duo-Prop 7.4L "LK"

        2006 Sun Tracker Party Barge 21
        Mercury 90 4-Stroke FI
        "Common sense is not very common"
        "Failing to prepare is preparing to fail." -- John Wooden

        Comment


        • #5
          Yes, tried that too - same result...

          Comment


          • #6
            Since you’ve tried several modules to no avail wanted to ask how you are measuring the advance ? With a advance timing light or timing tape on balancer ? Balancers can slip might be worth verifying TDC with a piston stop, also if you are using a advance light try to borrow a different timing light or check on another engine to verify the advance scaling is correct on the light, if you are using a timing tape is it actually the correct one for the balancer ? Just trying to verify the lack of full advance you see is actually correct

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            • #7
              I am using an advance timing light (brand new). I am reasonably sure this is not the light problem for two reasons: 1. If the timing was changing when shunt connected/disconnected I would hear (or detect, my timing light has the rpm reading) some changes in engine rpm; for my engine the timing should advance from 12deg base to 21deg@600rpm when shunt is disconnected - big difference, I definitely hear/detect rpm changes when adjusting timing manually by as little as 3 deg 2. 21 deg of advancement is optimal for my engine at idle speed, the timing light confirms it, the engine speeds up to 750rpm when I set timing to 21 (and slows back down to 600 when I retard the timing to 12) (the idle speed is set incorrectly for bad timing at idle, I'll need to bring it down once I resolve the timing issue)

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              • #8
                Could it be the resistor in the "pigtail" connecting the distributor to the coil? When I replaced the distributor I reused the pigtail. Now I am thinking maybe I should have bought a new pigtail. It looks like mine has 6.7Ohm resistor inside. Does anybody know what it should be? As I understand it, the value of this resistor would determine the voltage that the ignition module gets from the ignition system. Is it possible that the module would behave differently depending on the voltage it is seeing. Does anybody know anything about these modules? How does it "know" which engine it is sitting in? Looking at Volvo writeup, the same model ignition module somehow produces different ignition advancement in different engines...

                Comment


                • #9
                  There should be NO resistor in the line feeding the coil.
                  1998 Wellcraft Eclipse 24 Cuddy
                  Volvo Penta Duo-Prop 7.4L "LK"

                  2006 Sun Tracker Party Barge 21
                  Mercury 90 4-Stroke FI
                  "Common sense is not very common"
                  "Failing to prepare is preparing to fail." -- John Wooden

                  Comment


                  • #10
                    I am talking about the resistor shown on attached diagram under #22...

                    Comment


                    • #11
                      That is kinda interesting. My Volvo OEM manual calls that an inductor.

                      I do not have my boat here with me otherwise I would check it out for you.
                      Last edited by bruceb58; December 7th, 2019, 12:18 PM.
                      1998 Wellcraft Eclipse 24 Cuddy
                      Volvo Penta Duo-Prop 7.4L "LK"

                      2006 Sun Tracker Party Barge 21
                      Mercury 90 4-Stroke FI
                      "Common sense is not very common"
                      "Failing to prepare is preparing to fail." -- John Wooden

                      Comment


                      • #12
                        I am sure you have been doing some searching. I found this. Not sure how accurate it is:


                        https://bpi.ebasicpower.com/faq/delcoestwiring.htm

                        I am basically in the same boat as you are knowledge wise about what the component is doing here.
                        ​​​​​​​
                        1998 Wellcraft Eclipse 24 Cuddy
                        Volvo Penta Duo-Prop 7.4L "LK"

                        2006 Sun Tracker Party Barge 21
                        Mercury 90 4-Stroke FI
                        "Common sense is not very common"
                        "Failing to prepare is preparing to fail." -- John Wooden

                        Comment


                        • #13
                          Following I have the same ignition on a TBI motor.

                          Comment


                          • #14
                            The mystery just deepens (at least for me). I just got the "pigtail" (wire connecting the distributor with the ignition coil) for the new distributor. According to the seller (A-team), this is the pigtail that works with this particular distributor. Guess what, these are just straight wires, no resistors/inductors - nothing. My original distributor (Mallory, electronic) had the pigtail with ~6 Ohm resistor in it. If my understanding is correct, this resistor would limit the dwell current to 2Amp (tops). I am a bit scared to just take it out, will it damage the coil and/or ignition module? Lubak, what do you have between the distributor and the coil? Why does Delco put this resistor/inductor between the distributor and the coil to begin with? From what I read about Delco (HEI) ignition, the principal advantage of non-mechanical points is the ability to increase the dwell current (mechanical points do not last with dwell current above 3Amp), why limiting it?

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                            • #15
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                              So you replaced just the distributor with out getting the delco kit that comes as a complete ignition system ? If you google delco voyager ignition system you should see an entire kit that uses a unique harness between the coil and distributor, even comes with a coil, and harness to splice into the existing harness. If you are mixing and matching between the Mallory and delco systems that is likely your issue. I'd take a look at pictures and installation manual for this on line and install the parts that go with the delco system.

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