vertical grimmace

My Feedback: (1)

I was wondering if it would be possible to convert a DLE 20 to use a 1/4-32 plug? It seems like it would be great if the cap and plug were smaller to make it easier to hide. I was thinking possibly a threaded insert to reduce the size, then changing out the plug cap to suit this size plug.
Of course, I am going to bet that the plug will not reach far enough into the cylinder to perform properly, but it would be nice if it would be that easy, as my plane I have my DLE 20 installed in could benefit from this mod.

SrTelemaster150

It would be easy enough to counterbore the threaded insert to recess the smaller plug. That way, the the electrodes would be closer to the combustion chamber.

karolh

Those 1/4 x 32 plugs ain't cheap.

bcchi

Will run fine ,adapters are available.But it only takes about two drops of oil to foul out the 1/4x32 spark plug,if your engine is mounted inverted.
BCCHI

Lifer

My Feedback: (1)

Also, the plug boot isn't really that much smaller.

BadAzzMaxx

3/16" is all you save and changing the plug cap to the 1/4-32 is a pain.

See no reason to do it with a single ignition, Most set up require you to cut out the bottom of the cowl anyway.

If you do a lot of flying You will be happier with the CM6 plug.

Milton

pe reivers

Height gain is about 10mm, and yes, it can be done very well. RCexl has adapters that brin the plug eectrodes in position.
In scale planes those 10mm can be just the ticket, though the new 1/8" caps are difficult to assemble well. The resistor is already inserted, and must be pulled out to insert it in the HT cable first. Fix with glue shrink tubing, re-insert the sub assy in the cap, crimp the cap edge to the HT cable, solder the shielding wrap to the metal cap. Finish with a shrink sleeve.

Mikola

little plugs won't last so long...

vertical grimmace

My Feedback: (1)

I had a JBA 15cc and the thing I did not like about the plug cap was it wanted to rotate and come off. Maybe it is not worth it, I guess I was thinking out loud. I do fly scale models mostly and 1cm is a lot if it saves your cowling. I did not know about the fouling, and yes, my engine is mounted upside down.

What got me thinking is that the new VVRC, 40cc twin uses these plugs to reduce the width "footprint", to help with concealing inside the cowl. I was thinking why not have these small plugs on the 20cc as well. Maybe it would be nice if they just came stock that way, then no conversion.

As far as expensive plugs, how often do you need to replace them honestly? Other that touching the runway, it seems they would last a long time.

karolh

Our JBA15 taught us to stay away from those 1/4 plugs

SkyPilot101

I thought the new VV 40 twin is using angled CM-6's Not 1/4-20's ???

pe reivers

The RCexl 1/8"caps have J-shaped indentations that lock onto the plug hex. Push on the cap and then turn 1/12th rotation clockwise to lock the cap in place.
Unlocking, push down and turn 1/12th CCW before releasing.

SrTelemaster150

I ran the 1/4" X 32 plugs (C&H CDI) on an inverted Saito FA150 W/17% oil (Cool Power 15% nitro 17% lube)

Never had much problem W/oil fouling.

I did angle the engine slightly so that the exhaust port was straight down so oil would collect on the exhaust valve when not running.

Also, storing the plane so that the plug is on the high side, nose down in my case, helps.



You can get the Chinese 1/4 X 20 plugs for $12, sometimes less. I get better idle & the same or slightly better top end RPM from the Chinese plugs compared to the $30 Rimfires.


I have 1/4 x 32 plugs that have burned many gallons of fuel. I just soak them in acetone. blow them out W/compressed air & cycle the cleaned plugs through occasionally..

I don't think I have ever worn one out.

All of my experience is W/methanol fuels, but I don't see gasoline W/much lower oil content causing any problems.

As pointed out, the small hieght advantage can make all the difference in a scale application.