verifying your real advance curve

Discussion in 'Ignitions & starters and electrically related comp' started by grumpyvette, Mar 29, 2011.

  1. 87vette81big

    87vette81big Guest

    Steve Davis is the founder of Memphis Distributors.
    Also known as DUI or Davis Unitized ignitions.
    I found the article by David Vizzard interesting and informative.
    But I don't agree with all observations and tips recommended.
    If a Vacuum advance can is so great why aren't they used on Magneto applications?

    Also a Pontiac 455 with 1970 RAM AIR 4 Heads require only 32 degree BTDC total timing with 100 octanr leaded gas. 110 leaded 36 BTDC.
    Pontiac 6X smog era heads same timing total for peak power unleaded or leaded gas.
  2. bytor

    bytor Well-Known Member

    Attached Files:

  3. grumpyvette

    grumpyvette Administrator Staff Member

    thanks for posting the chart :mrgreen: its bound to be rather useful as a reference to many guys reading thru the thread

  4. legerwn

    legerwn Active Member

    Some of the best info on timing I have found without question,

    thanks Neal :D
  5. 87vette81big

    87vette81big Guest

    Its Interesting to see our posts Rick & Grumpy from 1 year ago.

    I always try & get the fastest advance curve possible on pump gas Rick.
    Pontiac & Olds V8 Seem to tolerate real fast advance curves.
    All in by 900-1200 RPM.
    I have real lightweight advance springs from early Mopar distributors I robbed them from.
    A few times I brazed a small glob of brass brazing rod pn the advance weights .
    Add a little mass in grams. Speed up advance.
    Different ways to skin the Cat.
    I never use the vacuum advance can.
    Leave it unhooked. Its for fuel economy purposes.

    Vertex Magnetos don't use Advance springs.
    I have custom filed by hand different ramps in stacked plates to get fast advance.
    Or even better lock it out for full advance for Race use.
    Leave Mag switch off. Crank engine & electric fuel pump on. Dtab the gas 2 times. Flip Mag switch on.
    455 Pontiac Roars to Life.
  6. Strictly Attitude

    Strictly Attitude solid fixture here in the forum

    I plan on doing that with my msd distributor when I do my cam but soon I will be able the adjust timing via ecu when I switch to coil per cylinder
  7. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    there is , without any doubt, at least... theoretically, long bloody scratch marks on the pavement,
    as I'm dragged kicking and screaming into the computer/digital era,
    but you really can,t dispute the facts and the facts are,
    that there are now ways to set the car engine ignition timing that were just not all that easy to duplicate with purely mechanical controlled ignition advance curves.
    between knock sensors that see and react to detonation, coil on individual spark plug ignition, crank sensors etc.
    and computer controls that allow you to select and set the degree of ignition advance,
    and sensors that read the fuel/air ratio hundreds of times a second, and allow the injector pulse duration to be adjusted to compensate if you have the correct matching software,
    at every few hundred rpm check points, its no longer a question that if you select the correct components you can pull power levels from engines that were previously very difficult to achieve.

    [​IMG] Extech Products
    having the correct tool to verify the engines operational temps would be helpful
    Last edited: Sep 3, 2018
  8. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    The CB Timing control is neat Grumpy.
    Vertex had a prototype in the works similar for thier Mags back in 2004.
    I wanted bad..project got dropped.
    Still have the sales Flyer.
    MSD has the 12 & 44 Pro mag seriers that do all that.
    $5k & 10 k still.

    Funny thing is with E85 and Turbos Timing control is not critical.
    Just give the timing it wants and done.

    Race gas the same N/A or Boost.

    Pump gas another story.
    CB come in handy.

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