Slick Mags - applications

[n144sh]

I'm trying to sort through what mags will work on my engine.

Here are the details:

Lycoming O320-A2A
Slick mag application chart says 4373 (Impulse) and 4370

Lycoming engine chart says that an O320-A2A is "same as A1A except fixed pitch propeller". Slick mag application chart for A1A lists 4371/4370 mags.

So the question is - does it matter, 4373 or 4371 for my engine? The Slick description says that 4373 has 20 degrees lag, 4371 has 25 degrees lag.

Thanks!

[mahlon_r]

Lycoming Service Letter 1443G lists the 4373 and the 4370 as the mags to use on an O-320-A2A.
Good Luck,
Mahlon"The opinions and information provided in this and all of my posts are hopefully
helpful to you. Please use the information provided responsibly and at your own
risk."

[n144sh]

Hi Mahlon,

Thanks much for taking the time to answer. Yes - I found that the SB that says 4373/4370 is the right mag.

I also found the Lycoming chart that says an A2A is the same as A1A except fixed pitch prop (solid crank I presume).

A1A lists 4371/4370 - why would it be different? I can't imagine if the only difference is solid/hollow crank that the mags need to be different????

Steve

[mahlon_r]

There is no real difference between the engine's. 320's don't have solid and hollow crankshafts, only hollow. I can't remember for sure, but the only real difference between them would likely be the prop mounting dowels and maybe the accessory housing having the capability to mount a governor drive on one and not the other. Anyway, the mag choice between them wouldn't logically be any different. The difference in the lag angle is minor and the difference in starting capability of the engine using either isn't noticeable to me. Many will say that if you time a mag at 25 you should use the 25 lag mag, but honestly I have never seen a difference in starting, using either mag on engines times to 25 BTDC. I think the likely reason that they have two different mags listed for the same basic engine is what was available when the engines were certified in an OEM application.
I think you will be fine using either mag. If you are a certified installation, you should use what Lycoming prints in the bulletin.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."