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Magneto timing questions

Draker

Well Known Member
Two unrelated questions:

1. I understand I need to be matching up the timing marks on the ring gear with a little timing hole on the starter. My starter (Sky-Tec) does not appear to have any such hole:





I don't recall if there are marks on the back of the ring gear, so the "case centerline" method might won't work. Any ideas? I'm considering E-mailing Sky-Tec.


2. Early in the engine install, I had to remove the magneto and re-install it. I did not use the locking pin while doing this. Should I expect to encounter difficulty setting the timing because of this? What is the purpose of that locking pin, given that I'll be re-timing it anyway?
 
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Hole

They should Be a little hole right here.. you can use a little drill bit in it to “extend” it out for better visibility.
 

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Yea, I thought that might be it, but it's not actually a hole--it's a threaded rod. Better picture of that here:

 
That’s odd, I haven’t seen a Lycoming without the timing hole there. You should have timing marks on the back face of the flywheel, and using a triangle pointer of aluminum may help act as a pointer. Is for your mag timing pin thing, yes you should reinsert the pin to be sure the rotor is at the #1 firing position. If not, you may not be able to time it with the limited movement the mag allows, or worse case, it’s off enough that it fires another cylinder instead of #1 and a kickback could break things. Have a local mechanic or experienced person show you the pin trick, they probably would have a spare pin to give you!
 
Usually the timing hole is kinda on the edge like here..but your other pictures don’t really look like it’s there..
 

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As long as you didn’t rotate the mag or the crankshaft while the mag was off, everything should be okay. If you did rotate either, pull the mag, rotate the mag gear until the distributor is on #1 cylinder, find closest place where holes line up so you can insert pin, insert pin. Put cylinder #1 into firing position, re-install mag, pull pin before rotating anything.
 
Yea, I thought that might be it, but it's not actually a hole--it's a threaded rod. Better picture of that here:


Mine is the same. A threaded rod. No timing marks on the back of flywheel for lining up with centre of case.
 
Mine is the same. A threaded rod. No timing marks on the back of flywheel for lining up with centre of case.


We've seen a few come through lately with the threaded rod instead of the hole. It is the proper mark to line up the flywheel marks, as we've verified it.

Vic
 
I had a hard time finding the mark on my starter ... it was there, but barely ... it looked like a bit of mold flashing, not a designed-in mark or a nice hole like I've seen in other pics. I've moved to the casing split line on top to confirm my timing.

EDIT: per the comments below, and some other interweb research, it seems that this XLT starter does not have a timing hole. I looks like the flashing on mine is approximately the right place, but still used the top case split line to do my timing checks.

"FYI, one other material change from the LS is that the XLT does not have the drilled ignition timing mark. This means that you have to use the top engine centerline for timing, and transfer the appropriate mark(s) from the rear of the flywheel to the front. This is not a big deal (and may be more accurate), but is different than the AMM."
 

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As long as you didn’t rotate the mag or the crankshaft while the mag was off, everything should be okay. If you did rotate either, pull the mag, rotate the mag gear until the distributor is on #1 cylinder, find closest place where holes line up so you can insert pin, insert pin. Put cylinder #1 into firing position, re-install mag, pull pin before rotating anything.

Bob, I did not rotate the crankshaft with the mag out, and used caution to not rotate the mag gear, however I don't know if, when I re-installed it, I managed to match it's position precisely with where it was when I removed it. I'll remove the mag and re-install it as you described, just to ensure.

And to be clear, in order to access the alignment pin hole in the mag, it is necessary to remove the housing that holds the ignition wires, correct?
 
Mags

Alignment pin is for Slick mags only. Lots of Bendix mags still out there. They require a different procedure.
I always use the timing marks on the aft side of the ring gear. Line the mark up with the crankcase split.
 
Bob, I did not rotate the crankshaft with the mag out, and used caution to not rotate the mag gear, however I don't know if, when I re-installed it, I managed to match it's position precisely with where it was when I removed it. I'll remove the mag and re-install it as you described, just to ensure.

And to be clear, in order to access the alignment pin hole in the mag, it is necessary to remove the housing that holds the ignition wires, correct?

My memory may be getting dim, but I don’t think you need to pull the cap for the pin. If you do pull the cap, you can visually verify that the distributor is on #1 when the engine #1 cylinder is on its compression stroke. There’s a fair amount of room (rotation) available for timing. I don’t think I’d pull the mag unless you can’t get the timing correct. In any event, pull the pin out as soon as the mag is back in; do not rotate the prop with that pin in place!
 
[QUOTEAnd to be clear, in order to access the alignment pin hole in the mag, it is necessary to remove the housing that holds the ignition wires, correct?[/QUOTE]

Yes, you have to remove the cap to access the timing hole int he mag.

Vic
 
Some starters have no punch or hole. I suggest you find TDC from the case half, and then mark it on your spinner to line up with a mark on something stationary from the engine, saves a lot of time an frustration in the future!

DAR Gary
 
While on the subject.... I have a "pumped up" (I) O-360, dyno 213 HP with dual "P" mags. Timing the P mags to TDC is normal, but I saw higher CHT than desired. Talking to Brad at P mag, he suggested that for the higher performance engines to retard the timing a bit. One tooth = 2.4 degrees, I tried one tooth retard with leaving the jumper in, and the temps came down about 15 degrees. Seems I was just flirting with detonation boundaries in lean cruise. I found no loss of airspeed. Some have retarded by 2 teeth, about 5 degrees, when the standard timing is 20 degrees instead of 25 BTDC with mags.
Just sharing an experience.

DAR Gary
 
I had a hard time finding the mark on my starter ... it was there, but barely ... it looked like a bit of mold flashing, not a designed-in mark or a nice hole like I've seen in other pics. I've moved to the casing split line on top to confirm my timing.

I don't think you're looking at the right thing...
 
The starter(s) in question appear to be Plane Power products. Maybe they have a unique system for the conventional timing hole found on B&Cs and older Delco starter bendix housings.

George
 
The starter(s) in question appear to be Plane Power products. Maybe they have a unique system for the conventional timing hole found on B&Cs and older Delco starter bendix housings.

George

Plane Power makes alternators, not starters, AFAIK. You may be thinking of Sky-Tec.

ETA: And I believe the answer is no, they also have the "hole" for timing on all of their models (but can't say for sure...some of their diagrams indicate explicitly the timing hole, others don't, but it is depicted).

The OP's pics show the hole with a bit of threaded rod in it. For whatever reason, maybe they're putting that rod in there now, but that's the timing hole. The other pics pointing to some imagined location on the edge of the casting are incorrect, to my knowledge, and those pictures clearly show the same timing "hole"/threaded rod. Timing to some bit of casting crud is bound to result in bad mag timing.

If you want to double-check that, just use the mark on the aft side of the flywheel aligned to the casing split line, then go look at the mark on the forward face and you should see it lined up with the hole/rod.

I usually just stick a drill bit into the hole and align that with the flywheel mark, but the "new" threaded rod in there obviates that option. I have no idea why that's being done now (maybe it's a moisture trap and could cause corrosion or something? Who knows.).
 
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Well, after a little head thumping I've decided I'm way out of my element with this one and could use some help. If anyone is in the KLVK area and feels like stopping by to help a mentally challenged person install a magneto properly, I'd be grateful. Send me a PM!
 
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Bob, I did not rotate the crankshaft with the mag out, and used caution to not rotate the mag gear, however I don't know if, when I re-installed it, I managed to match it's position precisely with where it was when I removed it. I'll remove the mag and re-install it as you described, just to ensure.

And to be clear, in order to access the alignment pin hole in the mag, it is necessary to remove the housing that holds the ignition wires, correct?

Yes, you have to take the cap off. It is held in place by 3 screws.

Vic
 
Just to update: I pulled the mag, used the timing pin to orient it correctly, and reinstalled it. After that, timing and synchronizing was a piece of cake. Thank you VAF and Barry at KLVK for walking me through everything!
 
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