jeffw@sc47
Well Known Member
Is the Lycoming IO-390-X available that can have NGK auto/cycle plugs installed instead of aviation plugs?
Jeff,
As already mentioned, you will need the plug adapters.
Give me a call, when you get a chance so we can discuss the P-mags and me doing another tech inspection.
I believe the IO-390 requires it's timing be set at 20? BTC. This means we will need to change the default settings on your P-mags. The jumper will only change the timing to 26.2?, which is too high for your engine.
Not exactly correct.
For the IO-390 (or 200hp IO-360) that specify 20 degrees BTC timing, the pMag is timed with the crank at 5 degrees ATC. This compensates for the pMag assuming a 25 degree BTC engine.
I recommend first running the engine with the jumper. This will limit advance to 29 degrees (34-5). Later experiment with the jumper removed to have max timing advance at 34 degrees (39-5). A switch to do this on the panel comes in handy.
Carl