Mailing List flyrotary@lancaironline.net Message #52135
From: Al Gietzen <ALVentures@cox.net>
Subject: RE: [FlyRotary] Re: Timing
Date: Thu, 16 Sep 2010 21:51:54 -0800
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

Lynn:

Is something missing; or do I not understand; see note below:

 

Remove all of the spark plugs.

 

Turn the engine in the direction of normal rotation until you can see an apex seal in the center of the trailing plug hole of the number one rotor housing. The rotor housing furthest from the prop. The upper plug is the trailing plug.

Removing the plug will reveal the hole.

 

Mark a flywheel starter tooth under your temporary pointer. Use welding wire or a coat hanger for a pointer, so you can bend it as needed. It needs to be well mounted and snug.

 

Once you have marked the tooth under the pointer with a paint drop, or chalk, or scrap of tape, do not move the pointer any more.

 

turn the engine backwards about 30 degrees, looking into the leading plug hole for the next apex seal to come to the center of the hole. The leading plug hole is the one on the bottom of the number one rotor housing. Once you have that apex seal centered make a second mark on a flywheel tooth or valley between teeth, whatever is under the pointer.

 

Half way between those two marks, make a third mark. This mark will be the TDC mark, accurate to about a degree. Clean the tooth with a fine file and paint it red. Count the teeth on the flexplate/flywheel.

This puts the apex seal at TDC.  What we want is the combustion chamber at TDC. The center of the indent on the rotor face is 60 degrees from the apex seal.  Rotating the E-shaft 180 degrees puts the rotor face at TDC.

 

Let us say that you find 106 teeth. divide 360 by 106 and get 3.39 degrees per tooth. So, for a timing mark at 24 degrees (for example) you would count off 7 teeth while turning the engine backwards. Mark whatever is under the pointer a different color than red. Make it bright like white or yellow. You can move the red dot back under the pointer. Remove the wire pointer and make up a permanent pointer to point at the red mark. So long as the engine is not turned during this process, all will be well. If you install more than one timing mark stamp what each is for on the spacer plate, with the correct paint dot by each line. 

 

Use only a clip on inductive timing light. clipped onto the leading plug wire of the number one rotor housing. 

 

Lynn E. Hanover

 

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