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Impulse Coupler click 45 Degrees past TDC

thelynns

Active Member
Hey Gang.

Getting ready to start up a 12 year old AeroSport power 0360 A2A.
1/2 hour total time on engine followed by a prob strike.
Engine got serviced and has been sitting ever since.

Light Speed EI on right and Slick Mag on left with Impulse Coupler.

Checking the Mag Impulse Couple spark timing by pulling the prop slowly by hand I noticed it clicks and sparks the plugs 45 degrees past TDC where as the Lightspeed is sparking at TDC?

Before I pull the mag to re-time it, does anyone know if this makes sense to setup like this when running 1 Mag and 1 Light Speed?
 
Pull it until it clicks, then back it back up and check the timing with a your buzz box. It is normal for them to click and become active well past the proper timing mark when you are pulling through by hand.
 
Don't know about Aerosport power but it is common for engine builders to run in the engine on the test stand using their own magnetos and install the new one(s) just before shipping. They don't always time them correctly when they do. Good that you are checking. An impulse coupling click 45* past top dead center means that the mag will fire about 25* (or 20* depending on the mag) before that in normal operation. That would put it at ~20* ATDC. The engine will probably run just fine on the Lightspeed alone as the combustion event will be well along by that time, but the magneto won't be contributing to the process at all. If the Lightspeed quits you'll have pretty much nothing.

Assuming that it is a brand new 12 year old mag, the internal timing should be fine. You just need to time it to the engine correctly and you should be good to go.
Hmmmm... just read about the prop strike. Ben is right. Get the mag checked. It might have done something to itself when it stopped.

Ed Holyoke
 
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