SPARK PLUGS.

[Lloyd BowersParticipant @lloydbowers78291]

Hi all, question is sparkplugs. where do you get them or do you make them?

im doing a specific one off 6cyl engine. and this is mostly my first model. although i do "dabble" and make lots of things. so sorry if some of my questions are simple or strange.

[Lloyd BowersParticipant @lloydbowers78291]

[JasonBModerator @jasonb]

What sizeplugs are you likely to need.

The CM-6 is common on larger models using an M10x1 thread and readily available from ebay etc.

For smaller stuff then the Rimfire range start a 10-40 which is approx 3/16 dia thread, then 1/4×32 and can be had from Minimag and Hemmingways.

Or make your own

J

[Lloyd BowersParticipant @lloydbowers78291]

ok im after 3mm if im keeping to scale, but i was looking at converting or making plug from nitro glow pulgs, i think there about 4-6mm.

how do you make your own, or i should say what material do you use for insulating?

[Bob PerkinsParticipant @bobperkins67044]

I'm currently building one of Jan Ridders engines. This includes plans for a spark plug, although I'm using a NGK CM 6. Jan specifies teflon for the insulator, steel for the body and steel wire for the electrode.

Bob..

[JasonBModerator @jasonb]

Corian is quite good for the insulator. Or let a lump of JB Weld go off and use that.

I doubt you wil modify a glow plug they are thereaded 1/4x 32 and the hole up the middle is 2.5-3mm

[Lloyd BowersParticipant @lloydbowers78291]

some helpful comments thanks. dont know what way to go, scale version of 3mm is a bit small to work with.

[Lloyd BowersParticipant @lloydbowers78291]

OK thanks. I did say if I was keeping to scale I’d be looking at 3mm. But as a novice I didn’t know what sizes are available or used normally. Ill have a bit more of a look and decide. I guess I’m going to be looking at 4-6mm.
Thanks

[JasonBModerator @jasonb]

Rimfire's web site gives sizes of their plugs which should give you something to go by.

 

Edited By JasonB on 06/03/2013 20:17:00

[Lloyd BowersParticipant @lloydbowers78291]

Posted by Graham Meek on 07/03/2013 09:27:06:

In his series of articles in ME April 1971, L. C. Mason says he sucessfully made some 4 BA spark plugs for his 4 Cylinder 4 cc 4 stroke engine, there is also a drawing for a 5/32 x 40 TPI spark plug with an Araldite insulator, these should be available digitally I would imagine.

Gray,

that would be good. ill have to start googling!!! cheers

[Ian S CParticipant @iansc]

There have been a number of articals in ME about making spark plugs, One used machinable ceramic, another, might be similar to Grey's teflon one, araldite I think was mentioned. An interesting one consisted of a metal body with a bit of glass tube melted into it, the tube came from inside an incandesant light bulb, the exposed insulator on top was a little ceramic insulator that you sometimes find on heating element lead in wires. Ian S C

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