O-320-E2A - which magnetos are correct?

[IowaRV9Dreamer]

I'm looking at the Lycoming Parts catalog for my Lycoming O-320-E2A. On page 4-1, it lists 3 magnetos for this model:
MAGNETO, S4LN-20
MAGNETO, IMPULSE COUPLING, S4LN-21
MAGNETO, S4LN-204

The first two are listed as impulse couplings, and I can't find a listing for the last one.

The Slick application guide lists 4373 for the left magneto, and a 4370 or 4373 for the right magneto. That would indicate that the left magneto is impulse coupled, and the right can be impulse or direct drive.

So I'm trying to figure out what to buy.... Looks like the left magneto should be impulse coupled... but can I go either way on the right mag?

Thanks for any help... I'm probably going to convert this to 160HP if that matters...

[jrs14855]

I believe the 200 series are shower of sparks. With the impulse mags you have the option of hand propping if the starter fails or the battery is dead. With the shower of sparks the engine can be hand propped but it requires an experienced person inside the airplane and some electrical power. It is potentially a very dangerous situation for the person swinging the prop. Dual impulse mags are typically found on airplanes with no starter, not necessary with a starter. The second impulse is just another potential failure point. So you would typically use a S4LN21 on left and 20 on right. Lots of different part numbers, for four cyl Lyc typical numbers are 10-51360-30 left and -29 right.

[Neal@F14]

Impulse on the left, plain on the right. Impulse on both mags is an unnecessary expense unless you plan on having no electric starter and will hand-prop exclusively.

The Slick 4300's have been rock solid reliable on my Cherokee's O-320-E2A for nearly 1000 hours.

The same kind of mags are running beautifully on my friend's brand new 9.2:1 compression IO-360 RV-8 that I get to fly. Only the left mag is impulse and this engine starts up effortlessly.

[IowaRV9Dreamer]

Originally Posted by Neal@F14

Impulse on the left, plain on the right.

Thanks guys - that's what I'll plan for... and I'll wire up the system so that only the left mag is "hot" when the starter is engaged.

It was very confusing since Lycoming apparently had a lot of magneto options for that engine.

I have Slicks on my O-235 and have been very happy with them so far.

[Neal@F14]

If you get the standard ignition switch from Van's or Spruce, it automatically grounds out the right mag when the switch is turned to the "Start" position.

[az_gila]

Originally Posted by Neal@F14

If you get the standard ignition switch from Van's or Spruce, it automatically grounds out the right mag when the switch is turned to the "Start" position.
---
Impulse on the left, plain on the right. Impulse on both mags is an unnecessary expense unless you plan on having no electric starter and will hand-prop exclusively.

...by removing a jumper.

I know several pilots that have converted to two impulse magnetoes just because the impulse coupling is a weak point.

With two impulse mags, you can still start the engine and get home if one impulse coupling fails. With a single impulse mag, you are usually stuck - very few folks are able to safely hand prop O-360s any more, and would you want the liability?

Lycoming has a service bulletin out that allows almost all of their engines to be converted to two impulse magnetoes for certified applications.

[9GT]

Originally Posted by az_gila

...by removing a jumper.

I know several pilots that have converted to two impulse magnetoes just because the impulse coupling is a weak point.

With two impulse mags, you can still start the engine and get home if one impulse coupling fails. With a single impulse mag, you are usually stuck - very few folks are able to safely hand prop O-360s any more, and would you want the liability?

Lycoming has a service bulletin out that allows almost all of their engines to be converted to two impulse magnetoes for certified applications.

My C-152 with Lyc O-235 L2C has both Slick mags with IC.