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Mag Check & Timing

B

Bill Phillips

Well Known Member
For my recent annual we re syn 'ed the mags on my 0360 A1A 180 hp Lycoming. The mags were still factory set and when we checked them they were at 28 degrees. We reset them to 25 degrees as our Lycoming manual shows. Prior to re setting while at 28 degrees my mag drops were very gentle at about 50-60 rpms. Ran great. Now at 25 degrees the mag check drop is about 90-95 rpm on both sides with a noticeable drop. Also, the plane does not seem to have as much kick as it did before. Is there an issue with having the mags at 28 degrees ?
Bill RV-8a Bluebird 107 hrs
 
No factory set

I wish people would understand that mags are not set by the Lycoming factory
they are just bolted on and must be set before first flight.
A friend of mine ran extremely high CHT in the first few hours before he realized that the mags were way out of spec on a brand new factory Lycoming.
As to where the right spot is for a mag is debatable, it's generally right for only one set of circumstances (MP and RPM) and a compromise for all of the other conditions.
Electronic ignition attempts through variable timing to have the spark plug firing event at the right time under most conditions.
 
Really

You buy a new lyco all set to go and they just bolt the mags on so they dont fall off but dont set them? I dont beleive that. Really?:confused:

I got a mattituck red gold and it was ready to rock, and had been run etc in a test stand with all paperwork/reports.

That makes no sense to me, am i missing something?
 
Two new engines, two sets of perfectly running mags, two engines run by the factory. If your settings have changed then be aware that something, points, may have changed. The 25 degree kick is what you want, not the extra 30 degree effect. :cool:
 
Lucky you

Turbo, either you are lucky or my 2 friends were unlucky.
A Matittuck is not a factory Lycoming ,it's far better
And so were my 2 engines from AeroSport, all set to go.
 
I find that a bit difficult to swallow as well

I swear my mag had never been touched from the time I unwrapped it to last week when we reset the timing. There has to be a Lycoming factory man here on the VAF site that could not get off to go to OSH. What say you O' smart one ? You build them and ship them. Slicks set before leaving PA? or just hanging there?
 
I just checked my Slick mags a year after first flight, installed by Aerosport Power. Not sure why but they were at 27* rather than 25. Either they both drifted exactly the same amount in a year of flying or they came that way. I have no idea which it was, but it's definitely worth checking regardless, even if your engine is brand new.
 
There is no way I will fly a brand new mega-thousand $$$$$ engine without checking mag timing, plug gaps, oil filter safety wiring, and anything else that gets checked during a normal condition inspection.

If an engine is flown with incorrect timing, that is an oversight by the aircraft builder.
 
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Another Aerosport testimonial ..

My Aerosport Power IO-320 was ready to fly when I got it ... mag was timed right at 25 degrees. The LSEI Plasma II on the right was just "plug in and go".
 
Sam Buchanan said:
There is no way I will fly a brand new mega-thousand $$$$$ engine without checking mag timing, plug gaps, oil filter safety wiring, and anything else that gets checked during a normal condition inspection.

If an engine is flown with incorrect timing, that is an oversight by the aircraft builder.
Click to expand...

Agreed. It never occurred to me that builders would just "bolt on and go"...

Wow!
 
Other side of the coin

Toobuilder said:
Agreed. It never occurred to me that builders would just "bolt on and go"...

Wow!
Click to expand...

I suspect that it would never occur to many folks to check the mag timing when they bought an engine that was supposedly test run.

I certainly would never have thought to check the timing if I had a report of the test run on a fresh built/fresh reman engine. Setting the timing and fuel metering should be done as a part of the test run sequence.

Cant imagine reading a test run report like this "engine test run for 2 hours, sputtered and ran hot-----probably needs ignition timing re adjusted and also possible carb adjustments"
 
We used to get bad parts right out of the box in the Air Force. First thing we did was give every brand new part a complete inspection before bolting it on the jet.

Run or not, a new engine should get an inspection of AT LEAST the scope and detail you would perform on a yearly condition inspection. Filters, timing, compression, condition and security, etc, etc...

After all, it's not the engine builder's life on the line.

...Perhaps it is my experience as an aircraft mechanic for my whole adult life that drives my distrust of things mechanical in general and other mechanics in particular.

The phrase, "trust, but verify" comes to mind.
 
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My understanding is that the engine is test run but the ignition and fuel supply are not. I ordered a new ECI that was test run 2 hours. They then removed their test carb and ignition and bolted on my new Precision FI and new P-Mags.
They have not been run.
 
Exactly right Mark !

That is how it's done.
The premium engine builders like Aero Sport, Mattituck and others will go the extra mile and correctly time your mag on your engine before delivery.
 
Mike S said:
Aha, low bidder gov contract stuff.

That explains everything.
Click to expand...

No, its just good practice to ensure to the best of your ability that an unknown part is servicable. That applies to stuff I get from Aircraft Spruce, Pep boys or Home Depot. Everyone can have a bad day, and like it or not, quality escapes happen. I just would rather mitigate the risk as much as possible

Now, I'm certainly not going to crack the case on a new engine just to make sure the mechanic installed the bearings correctly, but will I check the ignition, fuel and oil system? you bet! I don't care WHO built it... If it wasn't me, I'm not going to trust it blindly.
 
MarkW said:
My understanding is that the engine is test run but the ignition and fuel supply are not. I ordered a new ECI that was test run 2 hours. They then removed their test carb and ignition and bolted on my new Precision FI and new P-Mags.
They have not been run.
Click to expand...

N427EF said:
That is how it's done.
The premium engine builders like Aero Sport, Mattituck and others will go the extra mile and correctly time your mag on your engine before delivery.
Click to expand...

That is just so foreign to my way of thinking that I cannot even conceive of doing business this way.

At the very least I would not expect the untested parts to be bolted on to the run/tested engine.

I wonder if their corporate lawyers in the liability division know of this???
 
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ECI Titan

675 hours ago when I installed a new ECI Titan Eagle O360 on my 6A the mags came set at 25 degrees. Never had to set them until mag overhaul.
 
Mike,

I did not fly the plane the first time I started it. We ran a dozen or more tests for full power, rpm settings, fuel flow at high angle, low and fast taxi, cht & egt tests,vibration static tests, Mag checks at different rpms, fuel flow consumption, prop track and setting up the oil press and temp levels in the computer. We may have had at much as 2 hours of run time before flying all limited to how hot the engine was getting. The question I asked was and is will 28 degrees be an issue on the Lycoming engine? It ran better I think at that than the 25 degrees I set it to on my annual. If there is not problem with detonation or extra wear I may change it back to 28 degrees. Ran really fine for 104 hours at 28 degrees. Thanks, Bill w/ Bluebird
 
Mike S said:
That is just so foreign to my way of thinking that I cannot even conceive of doing business this way.

At the very least I would not expect the untested parts to be bolted on to the run/tested engine.

I wonder if their corporate lawyers in the liability division know of this???
Click to expand...

If the engine is being bolted to a 172, the A&P will certainly verify everything is in order before flight. There is no way an A&P could point to Lycoming after an in flight stoppage and claim "well, the magnetos looked tight when it came out of the crate..." No way.

There is no difference in "moral" responsibility between the A&P and an ametuar builder in my mind. If you're hanging a engine on an airplane, it is up to YOU to verify it is "safe for flight". Remember, the yellow tag is only "valid" until the part leaves the shop.
 
Bill Phillips said:
I did not fly the plane the first time I started it. We ran a dozen or more tests for full power, rpm settings, fuel flow at high angle, low and fast taxi, cht & egt tests,vibration static tests, Mag checks at different rpms, fuel flow consumption, prop track and setting up the oil press and temp levels in the computer. We may have had at much as 2 hours of run time before flying all limited to how hot the engine was getting. The question I asked was and is will 28 degrees be an issue on the Lycoming engine? It ran better I think at that than the 25 degrees I set it to on my annual. If there is not problem with detonation or extra wear I may change it back to 28 degrees. Ran really fine for 104 hours at 28 degrees. Thanks, Bill w/ Bluebird
Click to expand...

WOW, soooooo much thread drift.:D

Can someone answer the OP question.

I would like to know also because, like him, I did the exact same thing. I just figured that they used the Slick mags that were bolted on the engine to run it in the test cell..... silly me. As did the OP, I ran various tests before flight including static rpm and all seemed fine. I checked mine at last year's condition inspection and they were also 28*. I set them to 25* (per the timing remark on the engine data plate). Didn't affect the power a great deal but it does seem a little different than the original 28* setting.
 
GLPalinkas said:
WOW, soooooo much thread drift.:D

Can someone answer the OP question.

I would like to know also because, like him, I did the exact same thing. I just figured that they used the Slick mags that were bolted on the engine to run it in the test cell..... silly me. As did the OP, I ran various tests before flight including static rpm and all seemed fine. I checked mine at last year's condition inspection and they were also 28*. I set them to 25* (per the timing remark on the engine data plate). Didn't affect the power a great deal but it does seem a little different than the original 28* setting.
Click to expand...
Actually they probably where set to 25 when you started but you will never know since you did not check them. If the points erode/wear faster than the point cam the timing will advance, if the point cam wears faster than the points the timing will retard, your best to put the buzz box on and check at each oil change to keep a handle on possible drift.

Is 28 ok? Maybe but you’re a test pilot if you set it there intentionally, it’s specked for 25 to maintain the detonation margin Lycoming felt is required.
 
Russ McCutcheon said:
Actually they probably where set to 25 when you started but you will never know since you did not check them. If the points erode/wear faster than the point cam the timing will advance, if the point cam wears faster than the points the timing will retard, your best to put the buzz box on and check at each oil change to keep a handle on possible drift.

Is 28 ok? Maybe but you?re a test pilot if you set it there intentionally, it?s specked for 25 to maintain the detonation margin Lycoming felt is required.
Click to expand...

Thanks Russ. That's the answer I and the OP were looking for .... at least me :)

I'm learning more about airplane stuff everyday from guys like Russ. I didn't even thinking about the setting changing based on point wear, etc.
 
The last few posts are right on. 25 degrees is specified because it provides a degree of detonate protection at WOT. Even the Subby H6 went to that timing on take off. But as soon as the throttle is pulled back or MP decreases in climb timing advances. The engine will perform well at 28 degrees but that safety margin at high power is reduced.

I am a mag guy these days due a shift in perspective on keeping it simple. But when it was withEI in one form or another I always had a way to monitor timing. It was interesting to observe advances as much as 36 degrees in cruise. On take off it was always around 25.
 
Bill Phillips said:
Is there an issue with having the mags at 28 degrees ?
Bill RV-8a Bluebird 107 hrs
Click to expand...

Depends,
1). CHT plays a big part in detonation. // Cool cylinders are less prone to detonation.
2). Engine power demands @ different elevations. // Lower power setting and/or high elevations, equals less cylinder pressure.
3). Operating mixture preference. // Lean of peak, slower flame propagation.
The list goes on, these are the most common
 
MarkW said:
My understanding is that the engine is test run but the ignition and fuel supply are not.
Click to expand...

Hmm. I bought an IO-360-M1B through Van from Lycoming. The test run documents were included. My engine failed the first test run due to idle rpm. The injector was adjusted and the test rerun and passed. My assumption is that the injection servo that came with my engine (unmounted) was the one they adjusted during the test run. I cannot comment on the mags (Re: test run) other than I did check them before startup because I had loosened one to install the SD-8 PM alternator. Both were within a degree of 25. I'm anal like many other builders so I adjusted them both to 25. 1st annual showed one was at 27 and was subsequently adjusted. I'll keep an eye on that for the internal timing drift.

Edit *** I assume that the servo was removed to prevent preservative oil from fouling the innards. I wonder if the pickling process involves temporary removal of the mags?
 
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