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Prestolite Dual Point Advance Curve BACKS OFF! (retards 4 degrees)

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  • #16
    Back when I was a child, amassing my hoard of "hard" parts, the Delco was taken for granted. Only recently, did I realize it was only available for 2 years.

    And then there is the non-Delco single point distributor.

    Why? Oh, Why?
    _____________________

    Back to business...

    I'm thinking any of these "points conversion" modules. If they are nothing more than an electronic switch, the problem of dwell and wimpy coils is still present.

    I've never tried on of these 40 or 45k coils (I think there is a 58k canister out there too). I have an Accel 140001 - actually, it's from the Delco HEI conversion kit that lets you run an external coil (ugh! that was when I lost all faith in Accel and aftermarket ignition in general...) But it is academic - I'm not putting that bumble bee under my hood for all to see and jeer at!

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    • #17
      I think some of the points conversions maximize dwell and whack the stock coil with a pointed stick with a rusty nail in it for genuinely enhanced performance.

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      • #18
        I have to laugh. I don't think I've seen one comparison of points conversion modules on an ignition scope.

        And I believe with a scope, it is possible to determine the optimal condenser size for a given coil.

        But no one's talkin'

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        • #19
          Originally posted by tomhoo View Post
          I have to laugh. I don't think I've seen one comparison of points conversion modules on an ignition scope.

          And I believe with a scope, it is possible to determine the optimal condenser size for a given coil.

          But no one's talkin'
          But, you only need a condenser if you are running points with that coil. With a points replacement module, you do away with the condenser entirely.
          Bez Auto Alchemy
          573-318-8948
          http://bezautoalchemy.com


          "Don't believe every internet quote" Abe Lincoln

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          • #20
            Yes, I know the capacitor is irrelevant with a module, however, it's still an interesting conjecture.

            It appears both of my Heathkit ignition analyzers (one tube, one solid state) both work(!)

            What is interesting is that with my single points with dwell around 28*, does not behave like like the ideal waveforms.

            The ringing after the spark extinguishes is a damped sinusoid, however, it never damps to zero before the points close - and that is around idle speed. When you increase rpm, the dwell eats up the same portion of the 45* available, but the spark is a fixed duration which means as rpm is increased, the portion of the remaining 15* for the points to damp out the coil gets smaller and smaller. Around 4000, there is about 1/2 a sine wave and the points close.

            Now the frequency of the ringing is maybe 1/2 that of the pictures I've seen of an ideal waveform. The capacitor in the Delcos was .194uf which I thought was low - but the other Delco had the exact same capacitance. The Presto caps are around .24uf if I remember.

            I'm tempted to swap caps to see what it does to the waveform.

            ___________________________

            RE: Presto Weight Fix: Another fix would be to fab limiting stops into the bottom plate so that the cam plate does not limit the weights by the pins. If the stops engage the weights in the plane through their CG, the pin wear would be even and even when worn, the weights would do their job.

            _______________________

            RE: Dwell Meters that can work on a distributor chucked in a lathe: I have a Knight Kit Auto Analyzer that can do this either in a running engine or a distributor being spun on the work bench. This is not a common feature. I'm eyeing up a "newer" Knight 375A...

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