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Mag timing

M5fly

M5fly

Well Known Member
My dad and I started my condition inspection today and we're working on checking the mag timing but it's a first for both of us. We're using a buzz box and flower pot on the spinner and we appear to be getting 23° before TDC on #1. Do we adjust #1 to 25° and then the rest should be correct? Or should we be checking each cylinder?
 
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Can you provide some of the gotchas? My dad is an A&P and has been working on military jets for 40 years, just still learning the quirks of GA airplanes.
 
You do not need a flowerpot on your Lycoming. I wonder if you are having inaccuracies due to using it on your engine. You should have the timing marks on the front of the flywheel and align it to the dot on the starter, or you can align the top split of the case with the marks on the back of the flywheel (using a triangle scrap of aluminum as a pointer). This is of course after you “snap” the impulse coupling.
 
Pm sent with my phone number. Call me or better yet, have your dad call me. It’s not hard to time an engine, but there are some gottchyas that could get you hurt if you don’t do things right.
 
M5fly said:
My dad and I started my condition inspection today and we're working on checking the mag timing but it's a first for both of us. We're using a buzz box and flower pot on the spinner and we appear to be getting 23° past TDC on #1. Do we adjust #1 to 25° and then the rest should be correct? Or should we be checking each cylinder?
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When you think the timing is that far off (48*) the first thing to look at is the way you are taking the reading. Under normal wear, a mag will only be off a few degrees due to internal wear.
 
gasman said:
When you think the timing is that far off (48*) the first thing to look at is the way you are taking the reading. Under normal wear, a mag will only be off a few degrees due to internal wear.
Click to expand...
Corrected my original post to before TDC. Got the answers we were looking for from Tom.
 
I purposely set my engine at 23 degrees. No noticeable loss of power, but CHT's run much cooler and it's easier to run LOP mixtures.
 
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