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cpayne(at)joimail.com
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 Posted: Tue Oct 09, 2012 2:46 am Post subject: Spark plug heat range |
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I have both seen and tried many different heat ranges of spark plugs in my M-14P's over the last 18 years, ranging from #4 to #8 in the NGK series. My experience has convinced me that the "proper" heat range is related to how the engine is operated, assuming that the engine is in a satisfactory state of tune.
"Reading" a Spark plug's condition is one of those Black Arts that can yield valuable information to the knowledgeable eye. Less experienced tuners can still learn something from inspecting the plugs. Weak or leaky cylinders can be indicated, rich or lean mixtures as well as those spark plugs that only get a weak spark due to wiring issues.
In general, operation at high power settings, typical of Yaks and Sukhois used for aerobatic training, benefit from cooler spark plugs whereas cross-country cruise favors a hotter range. High energy ignition system use benefits spark plug condition but changes the normal "read". This is generally true of modified engines with greater compression, etc.
Currently, I use the "5" heat range because I operate my engine at Cruise I and Cruise II settings.
Craig Payne
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mark.bitterlich(at)navy.m
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| Posted: Tue Oct 09, 2012 6:44 pm Post subject: Spark plug heat range |
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Well said.
I run the 6 heat range because I run my engine between 85-100% ALL THE TIME. Rarely if ever do I pull it back. I used to... and then leaded up two cylinders exhaust valves, and with less than wise repairs ended up with cracked rings. I also change the plugs at least once a year. It's so cheap with auto-plugs, there is no reason not to. Why nickle dime plugs at that price?
Since that time I noticed that Hubie Tolson's M-14's had NONE of those problems, and he runs them HARD.
So I tried that. Worked for me. 85% on long flights, never less.
800 hours on the engine now, and it runs better than ever.
Of course I do not recommend this for anyone else, because I am not sure what the long term outcome will be.
I'll let you know.
But the M-14 really is a tough engine.
Mark
________________________________
From: owner-yak-list-server(at)matronics.com on behalf of Cpayne
Sent: Tue 10/9/2012 6:43 AM
To: yak-list
Subject: Spark plug heat range
I have both seen and tried many different heat ranges of spark plugs in my M-14P's over the last 18 years, ranging from #4 to #8 in the NGK series. My experience has convinced me that the "proper" heat range is related to how the engine is operated, assuming that the engine is in a satisfactory state of tune.
"Reading" a Spark plug's condition is one of those Black Arts that can yield valuable information to the knowledgeable eye. Less experienced tuners can still learn something from inspecting the plugs. Weak or leaky cylinders can be indicated, rich or lean mixtures as well as those spark plugs that only get a weak spark due to wiring issues.
In general, operation at high power settings, typical of Yaks and Sukhois used for aerobatic training, benefit from cooler spark plugs whereas cross-country cruise favors a hotter range. High energy ignition system use benefits spark plug condition but changes the normal "read". This is generally true of modified engines with greater compression, etc.
Currently, I use the "5" heat range because I operate my engine at Cruise I and Cruise II settings.
Craig Payne
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
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