Can one expect fouled plugs from operating on one mag

[woxof]

I had thought so but I am reading an article which says otherwise.

Of course, this is not normally done but one could do an extended check during the run-up or have a mag issue in flight.

 

[coloradobluesky]

I can tell you that if you do a mag check in the air and you turn it to the bad mag, when you turn it to the good mag, you're going to get a big backfire.

 

[Clark1961]

I can tell you that if you do a mag check in the air and you turn it to the bad mag, when you turn it to the good mag, you're going to get a big backfire.

Technically it's an after-fire and it can destroy the exhaust system. Not much fun to hear a loud 'bang' while trying to get the engine to run smoothly again...

 

[Let'sgoflying!]

I can tell you that if you do a mag check in the air and you turn it to the bad mag, when you turn it to the good mag, you're going to get a big backfire.

Yep, much better to completely shut it down.

 

[Ted]

I can tell you that if you do a mag check in the air and you turn it to the bad mag, when you turn it to the good mag, you're going to get a big backfire.

That is true. The correct thing to do in such a situation is to pull the mixture to idle cut-off, wait a few seconds, and then turn the mags back on.

To answer the original question, no. If you're doing a mag check on the ground that should not fowl the plugs. If your plugs are fowling that easily, they're probably getting old and have other issues, and therefore should be replaced.

I recommend Tempest plugs.

 

[Clark1961]

That is true. The correct thing to do in such a situation is to pull the mixture to idle cut-off, wait a few seconds, and then turn the mags back on.

I can tell you that pulling the mixture to cut-off on a single engine is really, really hard to do while diagnosing a mag problem in-flight.

 

[Ted]

I can tell you that pulling the mixture to cut-off on a single engine is really, really hard to do while diagnosing a mag problem in-flight.

Well it beats blowing the exhaust off of the airplane and having a fire.

 

[Clark1961]

Well it beats blowing the exhaust off of the airplane and having a fire.

Yabut the first instinct when the engine gets quiet is to undo the last thing you did. Switching back to both mags is pretty much what is going to happen unless you train to pull mixture after to switching to one mag.

 

[Ted]

Yabut the first instinct when the engine gets quiet is to undo the last thing you did. Switching back to both mags is pretty much what is going to happen unless you train to pull mixture after to switching to one mag.

Yes, I agree. That was why I made the point about what you should do so that you can plan for it.

On the Aztec, the mag switches (no key) were in a position that you could accidentally bump them with your left knee/leg/arm. I did on several occasions resulting in a Ted-induced engine failure.

 

[WannFly]

I can tell you that if you do a mag check in the air and you turn it to the bad mag, when you turn it to the good mag, you're going to get a big backfire.

Eek


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[WannFly]

That is true. The correct thing to do in such a situation is to pull the mixture to idle cut-off, wait a few seconds, and then turn the mags back on.

To answer the original question, no. If you're doing a mag check on the ground that should not fowl the plugs. If your plugs are fowling that easily, they're probably getting old and have other issues, and therefore should be replaced.

I recommend Tempest plugs.

What are your thoughts on fine wire Ted? Is it worth the 3 fold price tag?


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[Ted]

What are your thoughts on fine wire Ted? Is it worth the 3 fold price tag?


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I think it’s worth it on a turbo engine but not on naturally aspirated.

 

[BigBadLou]

Yabut the first instinct when the engine gets quiet is to undo the last thing you did. Switching back to both mags is pretty much what is going to happen unless you train to pull mixture after to switching to one mag.

Agree.
That's why I taught myself to touch the mag switch only with my other hand on the mixture, ready to pull. Not easy to train but it can be done.

 

[Tom-D]

Agree.
That's why I taught myself to touch the mag switch only with my other hand on the mixture, ready to pull. Not easy to train but it can be done.

All you really need to do is reduce the throttle setting. = Idle, 1,2,3,4,5, both. you won't get a bang.
Most all the exhaust systems I know have 2 or more cylinders pumping exhaust thru the mufflers, a 5 second pause will purge any unburned fuel.

 

[flyingbrit]

I had thought so but I am reading an article which says otherwise.

Of course, this is not normally done but one could do an extended check during the run-up or have a mag issue in flight.

I expect most of us were taught do do mag checks something like this: R only, Both (to "clear" the L plugs), L only, both. In reality though it is the temperature of the plug that keeps it from fouling under a given set of conditions such as mixture, lead content, oil etc. The plug temperature in turn is determined by the head temperature and the heat from combustion. Whether or not the plug is actually sparking probably makes little or no difference (as long as the other plug is sparking of course).

 

[Tom-D]

I expect most of us were taught do do mag checks something like this: R only, Both (to "clear" the L plugs), L only, both. In reality though it is the temperature of the plug that keeps it from fouling under a given set of conditions such as mixture, lead content, oil etc. The plug temperature in turn is determined by the head temperature and the heat from combustion. Whether or not the plug is actually sparking probably makes little or no difference (as long as the other plug is sparking of course).

IOWs, cylinder head temp are simply cylinder head temps, and spark plugs are part of the cylinder head.

 

[woxof]

Yabut the first instinct when the engine gets quiet is to undo the last thing you did. Switching back to both mags is pretty much what is going to happen unless you train to pull mixture after to switching to one mag.

I worry about doing that, so to prevent such an event, I select a mag and immediately release my hand. That way if the engine dies, it dies. I started doing this after noticing the instinctive place the mags switch back to both reaction.