SPARK PLUGS.

This topic has 10 replies, 4 voices, and was last updated 8 March 2013 at 01:22 by Ian S C.

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6 March 2013 at 12:33 #113880
Lloyd Bowers
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@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.
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6 March 2013 at 12:33 #6614
Lloyd Bowers
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@lloydbowers78291
6 March 2013 at 12:40 #113881
JasonB
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@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
6 March 2013 at 13:08 #113883
Lloyd Bowers
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@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?
6 March 2013 at 13:21 #113884
Bob Perkins
Participant
@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..
6 March 2013 at 13:58 #113885
JasonB
Moderator
@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
6 March 2013 at 14:14 #113887
Lloyd Bowers
Participant
@lloydbowers78291
some helpful comments thanks. dont know what way to go, scale version of 3mm is a bit small to work with.
6 March 2013 at 19:55 #113905
Lloyd Bowers
Participant
@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
6 March 2013 at 20:14 #113907
JasonB
Moderator
@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
7 March 2013 at 09:46 #113942
Lloyd Bowers
Participant
@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
8 March 2013 at 01:22 #113980
Ian S C
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@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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