R975 C4 magnetos

I am trying to get any information possible on setting up and timing the twin magnetos used on the 975-C4 engine (Bendix-Scintilla) Any leads would be very helpful.

Perry

[Alex Blair (RIP)]

Originally posted by pkitson
I am trying to get any information possible on setting up and timing the twin magnetos used on the 975-C4 engine (Bendix-Scintilla) Any leads would be very helpful.

Perry

Hi Perry...
There should be four positions on that ignition switch(Magnetos)
Right,left,both and off..
THe spark control is automatic and requires no attention when operating..
Magneto spark gap... .012
Here is the poo on the Bendix mags...
More info on starting...I wrote up a bunch of stuffa while back..we had a great discussion here a while back...
See here...
http://www.mapleleafup.org/forums/sh...highlight=r975

Some more stuff.........
1..Open the engine bay up to vent fumes..
2..Warm up engine comp.and oil tank ..(Important to remove condensate and heat up oilline to engine)
3..ignition..OFF..
4..Clutch...In..place transmission in neutral..
5..Turn over engine 45-50 times with hand crank..(If hydrostatic locked,remove spark plugs and drain cyls..replace and start over..)
6..With starter switch "On" crank over engine..no longer than 30 seconds..Watch for oil pressure rise on oil gage...while cranking..Should be 2-20psi ...depends on oil temperature,that is why you pre heat it..if no oil pressure try 30 seconds more..still no oil pressure..ckeck for air lock or loss of oil pump prime..reprime oil lines and pump.. and retry ..oil pressure must be established before fuel cocks are turned on..make sure oil is warm enough..the warmer the better..
7..Got oil preessure..??
Ok..open the fuel supply valves.
8..hold accelerator down slightly..about 1/10th open..
hold this position till engine starts to fire..
9..prime with hand primer...max.4 strokes..
10..Release clutch and engage starter..start counting1001..1002..put ignition switch.to the "Both" position...
11..Press the booster switch to the "on" position and hold...
DO NOT PUMP TH ACCELERATOR>>!
Do not push the start and booster at the same time..
Do not push the booster switch first..youll damage the booster coil..only hold on the boster coil for a short time..a coupple of seconds..
Once engine starts,release starter and booster switches and set throttle at 800RMP ..run engine for five minutes checking amperage...voltage...oil pressure(40-50 psi)..
12...Set throttle to 1000rpm for further 5 minutes..bringing oil press up to 60-80 psi...your engine oil temperature is absolutely critical to achieve these pressures so idle longer if oil pressure is low or unstable..
13..warmed up now..???
Set throttle at 2000 rpm,check oil amps and volts...check accelerator pedal at this point for smoth reving operation...
At this point check left and right magnetos by swithing them off one at a time momentaraliy..at 2000 rpm rpm should only drop slightly...as each is shut off..large loss of rpm would indicate firing problems with that circuit..
Engine oil pressure should be 50-80 psi and temperature should be 80-120F before moving off..
Failure to properly warm up engine and putting under load too soon will warp your air cooled engine..youll pay..big toime..
14..Set throttle to desired RPM and move off..
STOP>>>>

Bring back engine throttle to 800 RPM..
alow engine to cool down to previouse oil temperatures ..about 15 minutes..or you'll warp it..same as moving off too cold..dont shut engine down too hot..
Engine..cool..??
Press fuel cutoff solenoid and hold down untill engine stops firing
DO NOT TURN OFF IGNITION SWITCH UNTILL ENGINE
STOPS FIRING>>!!
Turn off battery and fuel valves..
Print this out and use it for a guide..Happy tanking..

[Alex Blair (RIP)]

Perry...

Maybe Hanno or Geoff can blow up the page shown here..
If not email me and I'll e-mail you the info.

Hi Alex,
I have the engine start-up and shut down procedure,what I am looking for is the procedure for rebuilding, installing and timing the magnetos after an engine rebuild.
thanks, Perry