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Autolite 386 Spark plugs
- Thread starter RicoB
- Start date
I see you are running mags. There is a conversion kit available to run auto plugs with mags and several vendors sell the 14mm adapters.
Ed
Ed
Here is a recent thread discussing the 386 plugs. Interesting. https://www.vansairforce.net/threads/pmag-spark-plug-guide.176556/
RicoB
Well Known Member
Hey Ed!
Long time no see!
I have been gone on jobs quite a bit.
Well, I have been running BR8ES since new. I am at my place in AZ, and I decided to do some maintenance here. When I removed my plug with the adapters, they were looking pretty bad. The threads were getting pretty rounded from cleaning throughout the 540 hrs. Since I am heading back on Sunday to LA, I needed something to get me back since I have a brand new set of adapters there.
Rico,
First off, you are asking for an apples to oranges comparison. Your NGK BR8ES are 14mm resistor plugs. The original use of these spark plugs is for cars. Users here on the VAF site are happy with them.
The Autolite 386s are 18mm resistor plugs. So if you have adapters installed, you would need to remove them to use the 386s. Some folks like the 386s, and some find them a bit to hot. If you want to try an 18mm plug, consider the Denso L-14U. I have heard nothing but good reports about this 18mm spark plug. They run cooler than the Autolite 386. Just remember to gap it to suit your ignition system. It is a non resistor spark plug, so you would need to either replace your plug wires with resistor wires, or install a resistor spark plug boot. The resistor boots are not expensive, easy to install and very durable. Available in 45 degree and 90 degree angle to the wire.
Denso L-14U Spark Plugs
NGK Resistor Spark Plug Caps
Charlie Kuss [rhymes with puss. German word for kiss]
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I have run them for many hours on my 320 with EI. I much prefer the l-14u plugs. First, they have a more appropriate heat range and two, they are nickel, so don’t rust like the 386s. I do not use resistor caps with these plugs and have no noise issues. My plug wires are low resistance taylors.
If you run these on mags, it is critical that you gap them at 016-018”. Even though they are auto plugs, they still must be gapped to the mags requirements. Gap is driven by the coil, not the plug.
If you run these on mags, it is critical that you gap them at 016-018”. Even though they are auto plugs, they still must be gapped to the mags requirements. Gap is driven by the coil, not the plug.
Toobuilder
Well Known Member
I know this is a 386 thread (which is a resistor plug), but there has been discussion of non resistor plug use here. Be VERY cautious about non resistor plug use with EI - I have personally experienced non resistor plugs (NGK B8ES) “scramble” the brains of Pmags in flight.
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I have run other non resistor plugs, even with resistor caps, and got all sorts of noise on the intercom and immediately removed them. I know the l14u’s are listed as non resistor plugs, but I think they have resistors in them, though may not be the typical 5k ohms. One of these days i will put a meter on them. I have run them in my 320 with ei for 1000 hours and zero issues.
RicoB
Well Known Member
What ignition system are you running with the L14-U?
I have megasquirt setups for both of my planes. Inexpensive and reliable, though you need to fabricate parts to pick up crank position. On the 6 / 320, I also use one mag.
