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Plugs IO-390-X for RV14A

jeffw@sc47

jeffw@sc47

Well Known Member
Is the Lycoming IO-390-X available that can have NGK auto/cycle plugs installed instead of aviation plugs?
 
couple more questions

? Is the engine direct from Lycoming via Vans available with the cylinders ready for the NGK plugs? or is that a modification?

? Which/where/who's - RV14 is using auto plugs and is it a Lycoming 390 or a 360?
 
Verify if you need long reach plugs for the 390, you probably do.
https://www.lycoming.com/sites/default/files/SI1042AB%20Approved%20Spark%20Plugs.pdf

SDS makes a long reach automotive spark plug adapter.

On this page:
http://www.sdsefi.com/cpi.htm

lycplugav.jpg
 
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.
 
Last edited:
N941WR said:
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.
Click to expand...

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
 
Carl Froehlich said:
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
Click to expand...

Carl,

I recommend setting the timing at TDC and programming the P-mags for 20° (19.8 is the real number.) This sets the starting timing at 4° after TDC and allows for using the standard process for setting the timing. This solves the problem of some future mechanic from miss-timing it.

Using the tool the way it is designed is always best.

I would not recommend running the higher setting on any of our engines, unless they have low compression pistons.
 
Jeff,

One other little detail I didn't include in my posts above is that you can download the EICAD program from the Emag Ignitions website and use that tool to adjust your P-mags. Here is the link.

When you are ready, let me know and I can come over and tune your P-mags.

Check your email.
 
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