Engine build beginning! Quick question about the mag

Just got notice today that Lycoming is about to start my Thunderbolt engine build. My plans have changed and I'm proceeding with one Lightspeed and one mag.

The question came in from Lycoming - Which side for the magneto? Any suggestions? Do I need to ask for anything specific for the mag?

Thank you!

Mag Configuration

I have 1 Lightspeed and 1 mag on my IO-360. Mag is on left behind cylinders 2 and 4. Wires go to lower aviation plugs. Lightspeed wires go to top auto-style plugs. Have a B&C SD-8 on the second mag platform.

Isn't LEFT the standard for one mag? Is there an advantage to being non-standard here?

And you probably want to specify an impulse magneto for that side for easier starting... This gives a spacer and longer studs for that side.

az_gila said:

Isn't LEFT the standard for one mag? Is there an advantage to being non-standard here?

And you probably want to specify an impulse magneto for that side for easier starting... This gives a spacer and longer studs for that side.

Click to expand...

I'm sure that is why they asked...different opinions, different installations.

Per convention, we start using the left ignition, and I'm big on basic operational factors being similar across a fleet. The EI is far superior to a magneto for starting so I'd certainly put it in the "left" position. Plus with the mag on the right (i.e. not used for starting) I could eliminate the impulse coupling. Parts not installed are absolutely trouble free.

Lycoming has guidance to use a retard breaker and not an impulse coupler on 540s. That said I'd ask lightspeed on their recommendation--however it seems like you'd want to use the EI for starting on the left position and a plain mag on the right.

I have a RV10 with an EIS and CMI mag; I put the mag on the RH side because it's easier to get to because of the oil cooler on the LH side. I used a CMI mag with impulse coupling; it's a tight fit but do able.

If it were me I'd put the standard mag on the left with a shower of sparks and the LSI (actually I would go with electroair or SDS) on the rght. Start on both.

EI on Left, Mag on Right

DanH said:

The EI is far superior to a magneto for starting so I'd certainly put it in the "left" position. Plus with the mag on the right (i.e. not used for starting) I could eliminate the impulse coupling. Parts not installed are absolutely trouble free.

Click to expand...

This is how I have mine set up. Lightspeed on the "Left" for ignition switch convention, and a non-impulse mag on the "Right." I've seen the damage that an impulse coupling makes when it comes apart, both to the engine internals and to the owner's wallet. The Lightspeed makes starting really easy. Yes, if I lose battery power I cannot hand-start it on the non-impulse magneto. But I suppose in that case my answer is that if I have no battery power for starting, maybe I should consider solving that problem on the ground, and not in the air.

Thanks folks! I'm looking for the standard setup so I'll stick with Lightspeed on the left, mag on the right.

I appreciate the input!