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Miss-tery miss.

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  • Ignition: Miss-tery miss.

    I have an ignition gremlin I can't seem to locate on the Lark 8; an irregular miss that causes a "surging" feeling at speed, usually light throttle. When I use an inductance type spark checker, it indicates an irregular miss when given throttle. I have done the following: new points, plugs (non-resistor), cap, rotor, condenser, coil, and vacuum advance. The latter was inoperable and replaced with new unit.
    I feel like everything I've done helps, but the problem seems to reappear after warming up. The only thing I haven't addressed is the plug wire set; they are gray 7mm "silicone" something-spark core that the PO installed. Could they be building resistance to where it misfires? It seems to be at all wires....maybe the coil wire?

    Thanks for any thoughts!!!
    Bruce

  • #2
    Have you run the engine at night looking for a "light show" between the wires? Make sure #3 & #5 spark plug wires are routed correctly. If they are not it can cause what your saying. #3 should be routed from the back while #5 should come forward & then back to it's plug.
    59 Lark wagon, now V-8, H.D. auto!
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    • #3
      What Warren is indirectly saying is do not route #5 and #7 next to each other. They are next to each other in the firing order and can have induced cross-firing if running side by side. So, as he says, the front pairing should be #1 and #5, and the rear pairing should be #3 and #7.

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      • #4
        Plug wire problems usually show up first as random misfire under heavy throttle/high revs.

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        • #5
          Did it always miss like this?

          Has someone removed and replaced the distributor since it ran well?

          I'd disconnect the vacuum advance and see if it still misses.
          I'm wondering if the distributor was installed incorrectly, and the distributor was twisted to compensate. The result can be that the rotor is not phased well relative to the terminals in the cap. If the rotor is too far away the spark may not be able to jump to the correct wire.
          https://www.youtube.com/watch?v=aWMlNwGW0tM

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          • #6
            You could be chasing a Unicorn on Electrical issues, why not try a Fuel Pump Pressure/Volume Test?
            StudeRich
            Second Generation Stude Driver,
            Proud '54 Starliner Owner

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            • #7
              Originally posted by StudeRich View Post
              You could be chasing a Unicorn on Electrical issues, why not try a Fuel Pump Pressure/Volume Test?

              Yep and toss in possible vacuum leak(s) and carb issues...

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              • #8
                Also check the valve adjustment.
                Rob

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                • #9
                  Read post #2 and #3 very carefully.
                  These are old time Studebaker owners and know their stuff.
                  The cross firing problems of #5 and 7 pistons is mostly ignored and some "experts" say that they use silicone wire sets and they will not spark over.
                  It is not a spark that causes the cross fire.
                  It is electrical induction that causes it. Think of the windings in a transformer.
                  You can do a search and look for failures of rods and bearings and most of the time it is #7
                  The power induced in the spark plug wire of #7 piston from the #5 piston that fires just when #7 is fully loaded and on its compressing stroke causes #7 to fire on its way up.
                  I have had a Studebaker 289 with a hole blown through the piston because of that.
                  I had a lady stop by the shop with a problem that her Studebaker stalled for no reason , at a stoplight.
                  I corrected the routing of her spark plug wiring and she called me a month later that her car had not stalled and that it run smoother than ever.
                  Look at the cars with the hood open at Studebaker meets and you find at least 50% of the spark plugs incorrectly routed.
                  Robert Kapteyn
                  Last edited by rkapteyn; 12-12-2015, 09:15 AM.

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                  • #10
                    Thanks for all the suggestions! I will investigate further, including a night time "light show" test!

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                    • #11
                      An update on this, even tho it's been a year since I took care of the problem.
                      Two things that I found: 1)Worn out mechanical advance springs; when open the weights would "kinda" spring back, but after replacing the springs they snapped back every time! 2) Portion of wiring harness had been compromised by a short in the charging circuit thus partially melting the pink resistor wire (the wires from the generator were marginally repaired and replaced in bits, and re-wrapped with black tape. I rebuilt this section of harness including a new pink wire. This V8 goes down the road with out missing a beat now!

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                      • #12
                        Thanks for getting back with the solution. I wonder if anyone was thinking of those things.
                        RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

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