Years ago on a dynomometer we tested 7 brands of spark plugs. The best of the lot were Auto Lite, and Bosck. The poorest were the most popular, Champion and NGK.
Using an adapter will not affect plug performance, only the heat range can do that assuming all other parameters are in compliance.
Our 182 (oil burner) uses Auto Lite, aka Unison, aka Tempest, and have far outlived the Champs. Our Searey amphip with 912 Rotax, came with NGK. Total time 35 hours, Autolites 600 plus and still in use.
I use Champion D9 18mm plugs to eliminate the adapters.
There is also a D6 plug that is cooler for higher compression engines.
The D6 heat range is roughly equal to an NGK 8 heat range. But I think the adapters make the plugs run hotter, so I use the D9s YMMV...
Has anyone had any problems using NGK's?
I have a Lyc. IO-360 with 10:1 compression dual LS ignition, using "Denso"
IK27 plugs, hard to find locally. Wondering what you LS guys are using as a substitute plug that might be more available? Champion, NGK?
Dick
Dick,
I use the Autolite 386 18MM plug which require no adapter. It has given me great service in 2 RV's and my HR2 for 15 years with an Electroair ignition. After a year of use they look clean and ready for more. I use Champion REM37BY plugs on the Mag side. I have also tried the Denso L-14U which work equally as well. The Autolite 386's however can be bought at NAPA for under $10. Highly recommended.
V/R
Smokey