Mag question

[Sid Lambert]

My left mag has increased in timing (not sure how much yet). I'm getting a large RPM drop when switching off the left mag during run-up. I also don't get any drop when I turn off the right electronic ignition. I've noticed my EGT's creeping up lately when they shouldn't be (full rich on the ground). I think these are pretty good indications the timing has increased.

My question is... What should I be looking for when I re-time the mag? Should I tear it down and replace any internals? (523 hours on the mag) I've never dealt with aircraft mags so I'm trying to get an idea of what to plan for.

[Mike S]

Originally Posted by Sid Lambert

Should I tear it down and replace any internals? (523 hours on the mag)

Yes, you should.

[Sid Lambert]

Originally Posted by Mike S

Yes, you should.

Thanks Mike.

What typically needs replacing? Is there a rebuild kit or is it done piecemeal? In my experience with other similar technologies the points will need to be replaced and is probably the cause of the timing drift. Am I far off?

I've been searching for L-1363B (slick rebuild manual) but can't find it online. <edit.. Found it.> From the price of the rebuild tool kit it may make sense to have someone rebuild it.

[Russ McCutcheon]

Hi Sid,

No, nothing needs replacing, well probably not, timing advancing means the points are wearing faster then the point cam, that’s fine. You need to remove the mag and do a 500 hour inspection and internal timing, then if all is good re install the mag, time it and your done.

I cant point you to any manuals or any thing like that, the best thing to do is get some help the first time, make him show you how to do this chore and the next time try it by your self. It’s all very simple and easy, you just need to know how then you’re golden!

Russ P.S. Mags can and do go to engine TBO with regular use and propper care.

[az_gila]

Originally Posted by Russ McCutcheon

Hi Sid,

No, nothing needs replacing, well probably not, timing advancing means the points are wearing faster then the point cam, that?s fine. You need to remove the mag and do a 500 hour inspection and internal timing, then if all is good re install the mag, time it and your done.

I cant point you to any manuals or any thing like that, the best thing to do is get some help the first time, make him show you how to do this chore and the next time try it by your self. It?s all very simple and easy, you just need to know how then you?re golden!

Russ P.S. Mags can and do go to engine TBO with regular use and propper care.

... for a 2008 Unison/Slick overhaul manual....

http://www.bomar.biz/download.php?view.1982

[wv4i]

Gil, Thanks for link to Slick repair manual, a good item for the tech library.

The thread starter should know that there is a Slick service bulletin that addresses timing going retarded up to 4 degrees, if that's what he means. Otherwise, agreed going advanced likely goes to point wear hopefully, possibly condenser as well. All assuming mag(s) have not gotten loose, rotated.

I just went thru a Slick mag drill apparently ultimately because of a bad plug, which can obviously cause RPM to be way lower on one mag than the other, and before it's taken out the mag completely. It's not rocket science to open and inspect one of these mags, but the internal timing is a bit tricky on reassembly. The repair manual will help. So will a neighbor that's an A&P!

Somewhere else I saw a suggested spec on plug resistance, 5k ohms or less. I had one, the bad one, that was open. Rest were either just below 5k ohms or even below 1.5k ohms. But, I'm buying a whole new set of plugs after this event.

This site is VERY helpful. Thanks to all.

[Sheldon]

I just went through my Slicks... See the link bellow for info and pictures.. Back up in the thread for the Slick manual link.. Sheldon

http://www.vansairforce.com/communit...t=31856&page=4