Cox 049 reed valve 3 fin glow heads

Coxfledgling Sun Mar 21, 2021 6:31 am

Would someone know the Cox part number for the standard Cox 049 reed valve 3 fin glow head, and, what is the resistance value when the glow head is serviceable please.

I need to check all the fitted glow heads and am not set up for "live" testing yet, so was thinking a quick resistance check first.

Obviously an infinite reading means a dead glow head, which may have an afterlife as I "converted" one to a glow plug head about 22 years ago that seems to work fine as it was run up from storage late 2019, then covid hit.

All help greatly appreciated.

balogh Sun Mar 21, 2021 10:46 am

I think the typical current a Cox glow head takes is about 2.5....3 Amps. This is the current range I use with a starting panel.

Cox 049 reed valve 3 fin glow heads Screen36

So if you use 1.5 Volts D cell batteries to start your COX, then
R=U/I = 1.5/(2.5...3) = 0.5....0.6 ohm...

KariFS Sun Mar 21, 2021 1:23 pm

It’s just like Andras figured:

Cox 049 reed valve 3 fin glow heads F7cf0610

The reading fluctuated from 0.2 to 0.5 ohms, but that’s probably because my multimeter is not a very high-precision instrument.

balogh Sun Mar 21, 2021 2:17 pm

Thanks Kari..this is one of those rare moments when empirical results and theoretical science resonate Very Happy

fredvon4 Sun Mar 21, 2021 2:38 pm

In this case the answer is IT DEPENDS

Resistance is variable with temperature

and don't forget that even a bright glowing filament my not run without current if the Catalyst is eroded or depleted or covered with 'Taters: Thus a bright glow or continuity is not a perfect indication of a GOOD glow plug

Coxfledgling Sun Mar 21, 2021 2:43 pm

Thanks guy's, a good starting point at any rate.

Please what are taters ?

Yes I suppose the acid test is will the engine start ...

KariFS Sun Mar 21, 2021 3:01 pm

balogh wrote:Thanks Kari..this is one of those rare moments when empirical results and theoretical science resonate

I must admit I had to wait a while for the meter to read the ”correct” value before documenting Very Happy

(Learnings from Laboratory Work 101)

Fred is right though, the only thing the measurement indicates, is that there is continuity similar to an unused OEM plug. If the platinum is gone, it’ll only glow when the battery is connected. Also the filament should be clean of course.

’Taters I think means potatoes. ’Maters are tomatoes... Learnings from hanging out here at CEF This Site Rocks!

Not sure what taters have to do with glow plugs though Huh...

fredvon4 Mon Mar 22, 2021 10:46 am

A few years back certain fuels had some sort of contaminant that would "grow" on the filament and had to be carefully chipped off with a tip of Xacto knife.....usually destroying the filament. If I recall correctly it was one of the Sig fuels used for stunt but not sure of the brand. Over time described as " 'taters" . Seen as a Blob of whitish-grey very hard contaminant "bead" built up near the weld to the plug.....mostly low nitro and hot plug

Coxfledgling Mon Mar 22, 2021 2:51 pm

Ahhhh, "whisker" like a 2t petrol....possibly...

One of the td09 heads glows but the engine doesn't run well, and seems to have a white " something" in the filament coil, that I don't want to touch as the coil would probably get broken....

I have 2 new heads, I have modified a dead 049 head to a glow plug many many years ago that seemed to work ok....

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Cox 049 reed valve 3 fin glow heads

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Re: Cox 049 reed valve 3 fin glow heads

Re: Cox 049 reed valve 3 fin glow heads

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Re: Cox 049 reed valve 3 fin glow heads