Timing Question

Dec 10, 2017 2:00 PM - 776 Views Create A New Thread

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Bill33

Blaine, WA



Can't get my initial timing down to where I want it.
My '33 has a heavily modified 383 Chevy Stroker in it (turned just over 600 hp on an engine dyno) and needs 36 degrees total timing to get the maximum performance. I'm running an MSD 6AL system with an MSD pro-billet mechanical advance distributor, part number 85551. I changed the advance stop bushing to a 23 degree unit, which I thought would reduce my initial timing to a minimum of 13 degrees, although I'm ok up to about 18 degrees, Right now, the initial won't go below 22 degrees, giving some kick back at times when starting. Am I misunderstanding something here or could it be something else other than distributor. The engine will idle down to about 1000 RPM with a very lumpy idle, which I don't mind, although the idle will jump up to 1200 sometimes. I'm running two heavy silver advance springs at the moment, but am getting confused a bit about the actual results of the different spring combinations. I have the other springs if needed. Any help would be much appreciated. Thanks, Bill









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Comments
  • Bill33
    Dec 30, 2017 at 10:48 AM


  • Yes, I can try that, it gets dark here around 4:30. Good idea Verne.

  • crdnblu
    Dec 30, 2017 at 10:36 AM


  • I understand your concern for your neighbors vs a healthy exhaust, but maybe late this New Year's eve, idle it in the dark, attach a ground wire from a known good GND to a long bladed screwdriver, and pass it all around your plug-wires in those areas near the valve covers. It's an old-school trick, but can yield some quick info re/ possible plug-wire leakage.......

  • Bill33
    Dec 29, 2017 at 3:00 PM


  • I don't think I have any crossfire, but my wire separators for each pair of wires on the heads are aluminum. Maybe getting some leakage there.

  • 36sedan
    Dec 27, 2017 at 10:41 AM


  • Something I just remembered I did on my motor that caused crossfire problems and real bugger to find. I was careful with wire routing everywhere except under the header pipes (see pict).


  • Bill33
    Dec 23, 2017 at 1:30 PM


  • Ok, tried a new cap and new rotor, brushed dilectric grease on all terminals inside and outside the cap. No difference. I set the initial now at 18 with and 18 degree advance stop bushing, which should give me 36 degrees total timing. I set the initial at 18, slowly rev up the engine and watch the timing advance up to 30 degrees, then it appears to start going backwards and loses track of the mark. It pretty much has to be interference as I've now tried 3 different lights and the car seems to run perfectly and the engine starts and stops well, no kickback or run on. Once I get it out on the road for some serious testing if it doesn't feel right, I'll take it to a friend who has an old Sun distributor machine. He can check the total timing and the curve. Thanks for the advice. If I ever solve it, I'll post the solution. My friend had it happen years ago on an HEI distributor and he never solved it, just used the distributor machine to prove the total timing and curve.

  • crdnblu
    Dec 22, 2017 at 7:34 PM


  • Just for "grins"........Try putting some dielectric grease on the terminals inside of the cap, as well as the rotor tip, then see what you get for timing. The jury is out on this, (pros/cons), but it might be worth a try, since you're planning to replace the cap & rotor anyway.

  • Bill33
    Dec 22, 2017 at 3:20 PM


  • Thanks Verne, I do have some wear on the terminals inside the cap and on the rotor, so will change those this weekend. I normally do use the dilectric grease on the plug wire ends going into the cap. My wires are MSD wires and are about a year and a half old.

  • crdnblu
    Dec 22, 2017 at 8:48 AM


  • From MSD:

    "Ignition Maintenance

    Even though we’re dealing with electronics, it’s important to inspect your ignition system. Remember that the ignition system, at least the high voltage side, requires maintenance. Over time, the rotor tip wears as does the carbon contact of the distributor cap. Spark plug wires also grow weary over time from delivering voltages that can range from 10,000 to 40,000 volts. Plus, your wires operate in a harsh, nasty environment with extreme heat cycles, moving parts, oils and fluids all working against them.

    It is recommended to inspect the cap and rotor at least once a year. If you live in an area with high humidity, you may want to inspect it more often.
    Visually inspect the cap and rotor for wear of the cap terminals and the rotor tip.
    Look for traces of carbon tracks where spark scatter occurs.
    Visually inspect the plug wires for burns or tears. Also, it is a good idea to periodically check the resistance of the wires so see if there is a wire with excessive resistance indicating a break in the conductor.
    MSD’s Spark Guard, PN 8804, is a dielectric grease that helps isolate the spark at the plug wire terminal and cap connection."

  • crdnblu
    Dec 22, 2017 at 8:40 AM


  • MSD offers this, (if you have the space), to help against possible crossfire:

    https://www.msdperformance.com/products/distributors/distributor_accessories/parts/8441

  • Bill33
    Dec 21, 2017 at 6:37 PM


  • Still don't get it. I called MSD and they suggested maybe I was getting interference on #1 that was affecting the light and suggested using #6 to see if that eliminated the interference, but it does the same thing on #6 as well. The initial sets fine and I can watch the timing advance up to about 30 degrees or so, then it appears to start sliding back as the rpm gets higher until it's back to zero or so. I wonder if it could be spark jumping around inside the distributor cap. I did clean out the residue in the cap with laquer thinner when I had it apart. I do have a new cap here, so will likely try that but it's really got me baffled.



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