Magneto Timing Process

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					Aviation Resource’s Magneto Timing Process Optimized for Cirrus SR 22 Aircraft

   1. Insure Magneto switch is off, remove key.
   2. Remove top cowl.
   3. Remove battery ground strap.
   4. Remove all top spark plugs, keep track of copper gaskets.
   5. Find TDC of #1 cylinder; identify prop blade face convenient for viewing digital
   6. Install protractor with double back tape and retention tape at end of prop blade
      selected in step 5. (Double back tape helps to remove any associated jiggle when
      ‘bumping’ the prop while checking the timing unit point ‘open’

   7. Back up prop and install TDC finder plug.
   8. Using digital protractor, locate ‘normal’ rotation stop point: note location angle
      #1. Reverse prop direction and locate stop point, note location angle #2. Remove
      stop pin. Do not move prop. Perform math (#1angle-#2 angle)/2=TDC angle.
      ‘Back’ prop by rotation to the TDC angle and continue to ‘back’ prop to the mag
      to engine timing degree setting (22 degrees). Insure protractor reading is
      “normalized” and note this angle number. This angle number is the BTDC angle
      of mag to engine timing. Further check that impulse couplings have released and
      install the timing indicator light tool to both mag “P” leads. DO NOT REMOVE
      THE “P” leads from mags. Install key in mag switch and turn to “BOTH”
      position. Install and ‘activate’ timing indicator unit and check the “point open”
       lights as prop is rotated. Note starting indications on digital protractor i.e. 22.5
       degrees left mag and 21 2 degrees right mag. (Log these numbers by mag to
       evaluate future mag to engine timing drift.) Adjust one mag to proper timing of
       22 degrees by using digital protractor indication, time second mag to 1st mag and
       check with digital protractor.
       Common digital protractors have a .1 degree resolution. Timing to .1 degree or
       less is possible in ‘mag to mag’ as well as ‘mag to engine timing’ Most digital
       protractors have ‘auto shutdown’ after a period of inactivity, reactivate (turn
       ‘on’) to view without worry of losing the ‘angle.’

  9. When timing is set to your satisfaction, remove protractor, remove timing
     indicator tool, insure mag switch is “off” and remove key. Check and service
     spark plugs for proper gap, lubricate threads, replace copper gaskets, install and
     torque to proper specs, Clean lead ends with Isopropyl alcohol, insure springs and
     contact buttons in spark plugs are clean of any corrosion, debris etc. and install.
     Install ground strap to primary battery install top cowl with all hardware (screws
     in front!) Perform ground run and test function of mag switch, engine operation,
     and mag drop/split. Perform required documentation for approval for return to
Feel free to call if you have any questions: 1st the Hangar during the day 715 822 5787
then the cell 715 491 1303.
Jim Barker, A&P/IA
Aviation Resources, LLC
101 Airport Ave Hangar 7
Cumberland, WI 54829