Piper COMANCHE PA-24-180 Service Manual page 467

PIPER COMANCHE SERVICE MANUAL
7C- 1. Removal Of Maneto. Before removing the mgneto, make ure magneto switches are off.
a
Remove the bamne uasembly cerminl plate from the magneto.
WARNING
The magneto is nor internally grounded; when the ground lead is
disconnected, the magneto is hot. Removing the harnes assembly
terminal plate first and insutlling it las minimizes the danger of suarring
the engine accidentaly when the ground lead is removed from the
magneto.
b. Disconnect the ground lead and the retard spark lead on the left mngnero, at the magneto.
c. Remove the nuts and washer and draw the magneto from the engine.
7C-52. Timing Procedure. (Inteand Timing.)
a. Remove the cover to the contact(s). distributor block, etc.
b. To internally tme the main contact assembly of either the dual-breaker magnetos or the
singie-breker magnetos, proceed as follows:
1. Loosen the nut securing the drive plate to the magneto shaft sufficenly
in
order to install the
Scintilla 114465 Rotor Holding Tool under the nur and fiac washer as shown in Figure 7C-10. Tighten the
nut securely.
2. Remove the timing inspection plug from the top of the magneto. Turn rotating magnet to
proper neutral position. This position is determined by locating keyways on drive end of magnet shalf at 12
o'clock with respect to name plate on housing. Tighten adjusting knob of 11-8465 Rotor Holding Tool
unul pressure is applied on housing flange preventng magnet from turning.
3. Loosen and rotate cam until cam follower of main contact assembly rests on highest point of
cam lobe. Adjust main contact assembly to obtain the clearance of 0.016 inch. Tighten main contuc
assembly secunng screws ro 20-25 inch pounds.
4. Install the 11-8693 Timing Plate Assembly and the 118149 Pointer Assembly of the 11-8150
Scintilla Tuing
Kit
to breaker companrment of magneto. (Refer co Figure 7C-11.) Align pointer assembly
with the 0 mark on uiming plate. Loosen adjusting knob of 11-8465 Rotor Holding Tool and turn rotating
magnet in normal direction of rotation unil pointer indexes with the respective E gap mark (15'
±
2 ).
Tighten adjusting knob of 11-8465 Tool and remove the 11-8149 Pointer Assembly from magneto. Using a
timing light, adjust main contact points to just open. This adjustment shall be made by rotcaing cam, in
opposite direction of rotation, a few degrees beyond point where contacts close. Then rotate cam in normal
direction of rotauuon until contacts just open. While holding cam in this exact position, push cam on magnet
shaft as far as possible with the fingers. Extreme care must be exercised in this operation. If cam adjustment
is changed in the slightest degree, the timing of the magneto will be thrown off. Do not drive cam on shaft
with a mallet or other insrument. Tighten the secunng screw tnereby drawing the cam down. evenly and
nghtly. Torque screw to 16-20 inch pounds. Loosen the 11-8465 Rotor Holding Tool adjusnng knob and
return rotatng magne: to neutral position. Renmsall the 11-8149 Pointer Assembly over 0
°
mark on timing
plate. Rotate magnet snai in normal direction of rotauon and check for opening of main contact points at
E gap settng (15
°
2 ).
POWER PLANT
ISSUED: 8/18/72
2 H13