blindfly

I've heard somewhere about a thing called "resistors" either in the plug itself or the plug cap.

how do i know if my ngk is resistored? does it say "r" like the champion's?

does anyone know if the plug cap is resistored on the new 3w 75i (new ignition)?

can i use champion "r" 's for this engine? (it came with the ngk so i didnt bother replacing...)

just the final adjustments befor the maiden flight this sat (wheater permiting of course),
dont want to loose my aw 31% edge on rfi/plug cap...[:-]


thank you for your fast replies,
enjoy the weekend...

Antique

My Feedback: (4)

The NGK CM6 plugs in the 3W are not resistor..The shielded cap and cable keep any rf from leaking out..There are 3 different 10mm resistor spark plugs made, Champion, NGK, and Denso..None will work with the shielded cap on the 3W ignition, and the Denso is longer than the other two...The only airplane engines currently using 10mm resistor plugs are the Zenoah G26s...All other airplane engines using 10 mm NGK CM6 spark plugs have the shielded cap and cable, so a resistor plug is not needed....

Diablo-RCU

My Feedback: (1)

Just to be complete, inside the spark plug cap (DA) there is a resistor between the copper multistrand conductor and the coil that clips to the end of the spark plug. So there is a resistor in the high voltage circuit, and it doesn't really matter where that resistor is located. I assume the 3W ignition also has an internal resistor, but I haven't taken one apart.

Antique

My Feedback: (4)

I just did, there is...Can't see why a resistor is needed if the plug cap and wire are completly shielded...There are thousands of Zenoah and Quadra and US Engines out there with no shield and no Bosch cap, just a solid wire and a rubber boot...None of my Zenoah (G23, 38, 62, and 445 twin) and Quadra engines ever had a shield or cap, just a resistor spark plug...No interference to my 1972 Pro Line AM radio....Or my Airtronics and Multiplex FM radios...
It's the KISS principle.....

Diablo-RCU

My Feedback: (1)

3W, DA, and ZDZ (Falkon) must be using the belt and suspenders approach - fully shielded ignitions using either a resistor in the plug lead or a resistor plug (ZDZ). ZDZ had a blurb somewhere that said you had to use the resistor plug as otherwise the microprocessor for spark wouldn't work properly. Perhaps 3W and DA have the same failure mode without a resistor in the circuit??

Antique

My Feedback: (4)

Don't know...DA and 3W have always used the shielded cap with the resistor, except for a 3W I saw about 12 years ago...The coil was INLINE in the spark plug wire..Looked like a snake that swallowed a small mouse..The module was in an aluminum box that looked like it was made from hardware store aluminum sheet, kinda bumpy..It was a terrible ignition...It was on the very first 3W I ever saw, I think it was a 70 twin, owned by Miles Reed and/or his partner...Mine and C&H and Silent spark ignitions will work with solid center or carbon center wire, and rubber boot or shielded cap, and resistor and non resistor spark plugs...Maybe the syncro spark module is different from the ignitions used by the other companies...You out there, Ed ?

ZAGNUT

My Feedback: (1)

i really don't know what the reason is for the 1000 ohm resistor in the 3W caps but i've tried running without it and things got screwy. might have something to do with limiting current through that wimpy little coil??


dave

blindfly

thanks everyone, you have been most helpful to give me my peace of mind.

good 2 go i guess...

will fire the engine tomorrow and do the test flight.

fingers krossed...[8D]