(providing you purchased 8 and got free shipping [...]
To get rid of adapters, I just changed to Denso L14-U from 14mm plugs. Here is my recent experience:
I have about 5 hours on new auto plugs: Denso L14-U recommended by many on VAF. (18mm plugs, no more adapters) After 4 hours on plugs I pulled one. It was very clean, hard to read tip color. Yesterday while climbing through 7,000 feet at full throttle I leaned to about 1200 EGT. Thought full rich (EGT around 1000) was too rich. Shortly after that the engine ran very rough. It was scary rough, thought it was failing. Oil temp & oil pressure were normal. CHT normal. It smoothed out as I reduced power. About 1700 RPM was normal/smooth. Put mixture full rich and put power back to 2350 rpm, ran normally. Eventually leaned a little after level at 9,500 ft. (I don't have manifold pressure or fuel flow indications). Did a full power run up after landing, was normal. What do you think? I have good idea, but want to hear others.
I have about 5 hours on new auto plugs: Denso L14-U. (18mm plugs, no more adapters) After 4 hours on plugs I pulled one. It was very clean, hard to read. Yesterday while climbing through 7,000 feet at full throttle I leaned to about 1200 EGT. Thought full rich (EGT around 1000) was too rich. Shortly after that the engine ran very rough. It was scary rough, thought it was failing. Oil temp & oil pressure were normal. CHT normal. It smoothed out as I reduced power. About 1700 RPM was normal. Put mixture full rich and put power back to 2350 rpm, ran normally. Eventually leaned a little after level at 9,500 ft. (I don't have manifold pressure or fuel flow indications). Did a full power run up after landing, was normal. What do you think? I have good idea, but want to hear all.
The Denso 5003 M22 is a colder plug with the same dimensional specs as the L14-U that might serve as an alternative if you were concerned about the plug temp.
How do you decipher the heat range for this particular plug part #?
Here is the 5003 M22. Do the same as above for the specs.
https://www.densoproducts.com/denso-5003-m22-nickel-spark-plug
The heat range is actually in the part number of most plugs. You just need the decoder table. Here is a cross-reference table for multiple manufacturers.
https://www.sparkplugs.com/heat-range-conversion-chart-2
The timing will help - are you running on the A curve or the B curve? Do you have an enginebridge or eicommander? They can tell you the pmag timing while flying. Our engines don't seem to be as sensitive to spark plug heat as the 2-cycle engines I played with as a kid, but it can't hurt to use a colder plug like the Denso IK24 5311 Iridium or the basic NGK BR8ES as recommended by Brad/Emagair. They require the 14mm-18mm adapter, and some seem to not like that, but doesn't seem to be an issue to me. The 14mm plugs are much more modern than the 18mm, and there is a lot more choice.IO-360, 9.5:1 compression ratio, Denso L14Us and dual Pmag Emags.
Got very pronounced detonation while climbing through 7,500ft with full power.
Throttled back considerably and mixture full rich solved detonation immediately. Max CHT temp was 405.
Thinking I'll retard Pmag timing a few degrees, and get colder plugs (maybe AUTOLITE 376s???)
Thoughts?
Yes this one wasn't decipherable by the part #. I ran Autolite 386's which were a little bit too hot but they worked. If I recall the L14U cross references to the 386. These should be better. The BR9ES plugs worked the best, but require adapters.
I was bitten pretty hard when NGK non resistor plugs scrambled the brains of both Pmags in my -8 some years ago, so I'm not trying that again.
I read every one of these 14 vs 18 mm plug threads and I've yet to find reference to an 18mm plug with a resistor. Does one exist?
I was bitten pretty hard when NGK non resistor plugs scrambled the brains of both Pmags in my -8 some years ago, so I'm not trying that again.
The Denso website says that the IK24 plugs have the 5k ohm resistor, and I confirmed this when checking both the IK24 and IK27 Iridium plugs. I have not yet put the IK24 plugs in - will probably do so next change.The Autolite 386 is a resistor plug. There are other resistor plugs like the 18mm Champion RD16 (comparable to the 386 in heat range). I've not heard of any issues with Pmags and the Denso plugs (non-resistor), but that's a reasonable caution.
The Autolite 386 is a resistor plug. There are other resistor plugs like the 18mm Champion RD16 (comparable to the 386 in heat range).
....I've not heard of any issues with Pmags and the Denso plugs (non-resistor), but that's a reasonable caution.
Maybe I experience preignition, not detonation, with my possibly counterfeit Denso L14Us, and my 9.5:1 compression IO360, but engine was really rough, was afraid of engine damage.
Which 18mm, resistor, cooler plug, has been used successfully?
Any experience with Autolite 376?
Maybe I experience preignition, not detonation, with my possibly counterfeit Denso L14Us, and my 9.5:1 compression IO360, but engine was really rough, was afraid of engine damage.
Which 18mm, resistor, cooler plug, has been used successfully?
Any experience with Autolite 376?
Not familiar with RockAuto but be careful out there.
I’ve been buying these plugs from RockAuto for over ten years - big name. Mine arrived yesterday, so they are definitely shipping. Or were…..
…but the manufacturer has discontinued the BR8ES 3961 plug.
Dang - they’ve only got three plugs left at that price….Just ordered 3961 from Rockauto for a $1.17 ea. plus shipping.
I ordered a bunch of the BR8ES from Aircraft Spruce this week. No stock issues.
These posts may run in evil circles.... the original post is years old. Then I see it in today's list. Makes me wonder why.
So I read the whole thing... which of course has gone on another tangent about heat ranges and so forth. It wanders back to the original question, are they discontinued? Seems not.
Thank God nobody posts about limited availability of toilet paper anymore.
While I recognize this thread seems to focus on the 14mm NGK BR8ES (which I use with great success) availability, the door is open on the 18mm options….Denso L14-U or Autolite 386s also work fine on a IO-360s without the need for the adapters (18mm threads). They are around $2 each.
Well, they are priced about the same.As a result of this original thread, I now own more BR8ES spark plugs than rolls of toilet paper!
[The life of a single guy...]