Cox glow plug insert size?

dontrinko Thu Oct 01, 2015 9:39 am

What are the dimensions of the Cox glow plug insert? I am considering using it to repair several non Cox heads. (Testor and Gilbert) Thanks; Don

pkrankow Thu Oct 01, 2015 10:10 am

If you are running a standard glow plug and drilling out the head for one you will need a 1/4-32 tap and the correct drill bit. (yes this is an odd size, also common on carburetor jets)

If you want to use a drop-in style then there is more work involved but the results will probably be better as a clamp ring needs made, which can be done from an old head with a lathe. I don't know the dimensions off the top of my head, but I can tell you that measuring different brands will offer slightly different results. The better inserts have a larger post diameter. The old chamber needs faced off leaving the threads, and the center drilled out. ...I suppose this could be done with lapping material (400 grit sandpaper) and a drill press with a good amount of care to retain a square face. Removing 1/8 inch of material freehand is not my idea of a good time though.

Now if you want to make a new clamp ring or plug adapter from bar stock I don't have much help...

Phil

Oldenginerod Thu Oct 01, 2015 7:15 pm

dontrinko wrote:What are the dimensions of the Cox glow plug insert? I am considering using it to repair several non Cox heads. (Testor and Gilbert) Thanks; Don

I could measure one up for you when I get a chance later but someone will probably beat me to it. I doubt the technique will work with the Gilbert as I don't think the flange will be wide enough to seat on the step in the bore, and the Gilbert threads are very shallow. The only way to overcome that may be to recess the whole insert flange rather than face off the head which would reduce the threaded area too much. The insert would need to be sealed into the head and pinned to retain it, unless you could get a really neat press-fit.
My big question would be whether a Cox insert could be machined down enough to fit into my Torpedo Junior .035. I don't have adequate equipment or skills to do that.

Rod.

Oldenginerod Thu Oct 01, 2015 9:25 pm

Ok Don, here goes.
The base flange diameter is 12.8 mm (1/2"), flange thickness is 1.3 mm, body diameter is 8.5 mm and height from top of flange to top of main body is 9.7 mm. Hope this helps.
Rod.

Cox glow plug insert size? Drop-i10

(Thanks Cox International.)

dontrinko Fri Oct 02, 2015 4:57 pm

Thanks. Don

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Cox glow plug insert size?

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