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Installing Right Mag

Louavul

Louavul

Well Known Member
Attempting to install a Bendix mag in the right position on my recently assembled ECI O-360 A1A. This mag does not have an impulse coupling.

It looks as though this mag will bolt directly to the accessory case as that gives me full gear interface with the idler however, this allows for too much stud preventing the nuts from being run down. With the impulse coupling spacer installed the studs are just the right length but, there is no contact with the idler.

So, question is, do I need a longer mag drive gear to use with the spacer (IPC shows spacer installed) or shorter studs when the spacer is removed and the mag is attached directly to the accy case?

Neither my IPC or Overhaul manual addresses this or I haven't found it yet. I have found a SB that allows for a different spacer/drive but, it doesn't seem to be for my specific engine, cost of which gives me the creeps.

Thanks,
 
Mags

Some engines are set up for dual impulse mags. The non impulse do not use a spacer. You will need to replace the studs with shorter studs. Any four cylinder Lycoming parts manual should list the proper stud.
If the current studs are configured so that you can install the special thick washer, lock washer and nut without bottoming out the nut on the unthreaded portion that would be ok. Just don't use a stack of washers or spacers under the nuts to fix this.
 
jrs14855 said:
Some engines are set up for dual impulse mags. The non impulse do not use a spacer. You will need to replace the studs with shorter studs. Any four cylinder Lycoming parts manual should list the proper stud.
If the current studs are configured so that you can install the special thick washer, lock washer and nut without bottoming out the nut on the unthreaded portion that would be ok. Just don't use a stack of washers or spacers under the nuts to fix this.
Click to expand...

To be more specific - from the Lycoming SB above...

When the impulse coupling magneto has been removed, remove the two P/N 31C-19 studs from the accessory housing and install P/N 31C-12 studs. If minimum (25 in. lbs.) drive torque cannot be reached, install the next larger size oversize studs. The specified driven stud height is .94-.98 in.
 
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