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Right-hand Mag Removal Advice

Auburntsts

Well Known Member
I've got to remove the right mag on my IO-540 to replace a leaking gasket. Any advice or gotcha's I need to be aware of during the removal and subsequent re-installation? I've got the Slick L-1363C Overhaul and Maintenance manual plus Tim Olson's version of the SkyRanch mag instructions, but never having removed a mag before just want to make sure I'm not missing anything.
 
Watch for falling FOD

I'm always concerned about dropping a piece of hardware into the open mag hole during removal and re-install.

I remove the top fastner and hold down block completely before removing the bottom fastner when removing a mag and do the bottom first when re-installing.

I cover the open mag hole with a clean rag while the mag is out. If you happen to have a mag hole cover (like the ones get if you have a Lightspeed ignition) that's even better.
 
Before you remove it, set the prop at 25 degrees BTDC on #1 (or whatever your timing says). Be sure it is #1 firing stroke, not #1 exhaust stroke by putting a finger over the spark-plug hole and feeling for compression.

mark on the rim of the mag with a sharpie or a piece of masking tape or something where the hold-down clamp parts touch on the rim of the mag. Sometimes you can see the compression marks in the paint and you don't need to mark it.

Then, while the mag is out, DO NOT turn the prop. When you reinstall it, with the special pin that locks the mag in the firing position, you can pop it in matching the marks to the hold-down studs, put the hold-down blocks and nuts on finger tight, and hook everything up, knowing that you will be really close to the correct timing.

BE ABSOLUTELY SURE YOU PULL THAT PIN OUT BEFORE YOU MOVE THE PROP.

Set the final timing with the buzz box. Normal safety procedures apply, i.e. disconnect all the ignition leads or pull the plugs.
 
Thanks fellas! With regards to inserting the T118 timing pin, is that something I should try to do as I'm puling the mag off (if that's even possible) or wait until it's been pulled completely off the engine?
 
Thanks fellas! With regards to inserting the T118 timing pin, is that something I should try to do as I'm puling the mag off (if that's even possible) or wait until it's been pulled completely off the engine?

no. It creates risks if you are not carefull and doesn't help. Pin goes into some thin and weak plastic inside. Only necessary for installing. Also, note there are holes for both R and L rotation. Be sure to use the correct hole. I just use a drill bit. I think it is 1/16", but don't recall. Easy to measure.
 
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no. It creates risks if you are not carefull and doesn't help. Pin goes into some thin and weak plastic inside. Only necessary for installing. Also, note there are holes for both R and L rotation. Be sure to use the correct hole. I just use a drill bit. I think it is 1/16", but don't recall. Easy to measure.

The benefit of using the proper pin is that it has several stepped diameters and absolutely only fits in one place all the way in. Using a 1/16" drill rod can work, but I think there may be other positions of the parts that will allow it to go part-way in, and you don't have much of an indicator that it is all the way in. So I prefer to use the real Slick-Champion part.

The mag data plate will indicate left or right handed rotation (not the same as left or right mag position on engine). That tells you which hole to insert the pin into.

Also, it was pointed out by Dave Howe that 6-cylinder mags apparently have a different drive coupling than the 4-cyl drive gear that I am familiar with, and apparently it can be tricky to keep the coupling assembled while inserting without having a part fall into the sump. I wasn't aware of that. All my suggestions for setup to make it easy to get the timing right on re-install still apply, but would be good to hear advice on how to keep the coupling together right.
 
I'm always concerned about dropping a piece of hardware into the open mag hole during removal and re-install.

I remove the top fastner and hold down block completely before removing the bottom fastner when removing a mag and do the bottom first when re-installing.

I cover the open mag hole with a clean rag while the mag is out. If you happen to have a mag hole cover (like the ones get if you have a Lightspeed ignition) that's even better.

Smart! Dropped a nut last month reinstalling Slick...OMG! I feared the worst when I couldn't find it for about 15 minutes. Then I found it resting risklessly in the joint of the motor and nose gear mount. That was a very happy moment!!!
 
The 6 cyl has the rubber drive cushions, be careful not to let them fall into the engine, pull the mag straight out very slowly/gently, the rubber cushions will probably stay in the mag drive inside the engine but you never know. I like to install new rubberss if the engine has very many hours on it. Glue the new cushions on the mag before installing.
 
The benefit of using the proper pin is that it has several stepped diameters and absolutely only fits in one place all the way in. Using a 1/16" drill rod can work, but I think there may be other positions of the parts that will allow it to go part-way in, and you don't have much of an indicator that it is all the way in. So I prefer to use the real Slick-Champion part.

Fair points and I should be more cautious with advice. I have disassembled them many times and know what is inside and how far the bit goes in as well as a feel for when it goes through the hole in the rotor. I should not assume everyone would be in the same position.

Larry
 
The 6 cyl has the rubber drive cushions, be careful not to let them fall into the engine, pull the mag straight out very slowly/gently, the rubber cushions will probably stay in the mag drive inside the engine but you never know. I like to install new rubberss if the engine has very many hours on it. Glue the new cushions on the mag before installing.

Walt, what glue do you recommend? A tiny drop of superglue or??
 
Grease

Walt, what glue do you recommend? A tiny drop of superglue or??

I was taught to use grease to hold the rubber couplings in place while installing the magneto. BTW, a buddy had one fall inside an engine once when he pulled the mag. He took a blind stab with a scribe and brought it up on the first try.
 
I was taught to use grease to hold the rubber couplings in place while installing the magneto. BTW, a buddy had one fall inside an engine once when he pulled the mag. He took a blind stab with a scribe and brought it up on the first try.

I've used the grease trick and obviously didn't have the right grease. The little couplings just fell right off. I must have picked them up off of the floor and cleaned one or both 3 or 4 times only to have the same thing happen again and again. Next time, I'll try one of the glues Walt suggested.
 
Newer mag drives have a slot machined into the cup that holds the rubber drive isolators. New style mag drive rubbers have a rib on the rubber that fits into the slot on the drive to hold them from falling out of the drive. So if you have a newer engine of newer drives you don't have to worry about losing the drive rubbers. Always best to be cautious till you know for sure. Anytime, I dropped one off the drive into the engine ,I was able to get it with a pair of mechanical fingers after about a 1/2 hour of trying. Frustrating but possible!
Good Luck, Stay Home and Stay healthy,
Mahlon
 
Magneto Drive Modification

I had my magneto "modified" by my friendly, local overhaul facility to the new configuration. They could, because my engine is now considered "experimental" and not bound by certification constraints.

Your local shop may not be willing to jump across that gap to the "dark side", but if they do, you'll be much more confident of a proper install, without losing the drive coupler, when the time comes.

YMMV

David Howe
Harmon Rocket II S/N 002
 
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