Tuesday, July 13, 2010

Setting Slick Magneto Point Gap

.008 to .010 inch for Slick 4300/6300 series magnetos. But Wait!  You do not set point gap. You set E-gap. On the Slick magneto, E-gap is critical; not point gap - much easier starting!  One establishes E-gap (point opening at defined rotor position) and then point gap should be within the limit range.

Shown here is the E-150 E Gap Tool being used to set rotor position. Then use your timing light to detect point opening. By point gap we mean the maximum distance the contact points separate. Reference the Slick Maintenance manual for complete instructions on setting internal magneto timing.

Slick E gap timing tool(red arrow) inserted into slot in rotor and against poll shoes. Notice how magneto is oriented with the coil up.  Locate the appropriate L or R timing slot (shown in lower picture)   on the rotor magnet and insert the notched end of the T-150 into the L slot for Left-hand rotation magnetos and the R slot for Right-hand rotation magnetos. 

Place tool on Left side for L magnetos and Right side for R magnetos. Rotate the magneto clockwise for Left-hand rotation and  counterclockwise for Right-hand rotation magnetos until the T-150 rests against the pole laminations.  The magneto is now at the E gap position. Adjust the points to be just opening and you have set inernal magneto timing.  Point gap opening should be .008 to .012 inches. Torque adusting screw to18-20 in-lbs. Torque the pivot screw to 15-18 in-lbs. Note: many mechanics do not use this simple tool. They estimate E gap. Comparing this method with the tool shown above you can be off considerably. This may account for differences in rpm drop between magnetos when doing the magneto-check.

T-150 Slick E-Gap Timing Tool

Thickness: .060 inch
Length: 2.90


  1. I could have used this tip a couple of weeks ago. in Slick's overhaul manual L1363E page 7.4 item E they explain setting the E gap with a lite or buzz box and then follow it up with a line that says the gap will be .008-.010. I took that to mean the E gap opening and not the max point gap. not to mention that your photo is 1000 times better than their line art for illustration purposes. thank goodness for Joe @ Slick.

  2. Hello, Mr. jhrubos
    The weather is very cold I'm wondering what the weather at that place.
    I live in Republic of Korea, and my name is jaeha.
    It's a dream it is to be the best aircraft mechanic, Mr. I got a question for jhrubos leave a message.
    I'm in maintenance of aircraft slick magneto 4300 series are used.
    You're referring to information provided by the slick magneto point gap spacing as "E-gap" is the location of the gap found
    I'm terribly sorry to have bothered you, but
    The publisher of this document to me that the detailed description would be appreciated.
    Thank you

    e-mail : originaljaeha@yahoo.co.kr

  3. E gap is not a gap.
    E gap is not the same as point gap.

    Set E gap -- then inspect for proper point gap.

    This is all explained in the Slick Service Manual that you should have if working on the magneto.

  4. bchipley2:20 PM

    Good "points" John.
    Point gap is a little smaller in the 4300/6300 manual L-1363F dated 01-05-11. Page 7-4 shows proper "E" gap setting will provide a point gap of .008-.010" with the points fully open. With a 6310 mag set up this way I have expeirmented on the test stand with the recommended 5mm (0.20")test spark gap. Opening the point gap to just .012" the mag begins to fire unevenly and at .020" pt gap the mag doesn't fire at all. And further expeirmenting with improper e-gap or point gap setting really shows up on a test stand. They don't jump as big a spark gap. A mag can be set up a little out of tolerance and run just fine on an engine with a normal spark plug gap of .019" but with time will likely wear so far out of limits one may loose the customer before the next 500 hr inspection!

  5. bchipley, good catch on point gap.

    Point gap used to be 8 to 12 back in 1993 but evidently was changed to 8 to 10 in the current 2011 manual. Your comment goes along with what I have experienced that if it is not set up correctly it doesn't work so good.