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RICHARD GREEN 218/12/2016 16:53:03
324 forum posts
192 photos

I've got the recommended Primus 8842 burner for the hot tube on the Alyn foundry 1/2 size Gardner gas engine,

Does anyone know what the thread in the burner is?

Also does anyone know where I can get fittings to connect to say 1/8 copper tube ?



Steven Vine18/12/2016 18:31:03
340 forum posts
30 photos

Hi Richard

I just measured the male thread on the neck tube, and the male thread on the jet.

Mine are pretty old and worn so I get varying readings.

It looks like a 0.75 pitch.

The thread diameter measures just under 8mm (0.302inch to 0.31inch).

I think it is an 8mm x 0.75, but best to get confirmation.


Michael Gilligan18/12/2016 18:34:35
19589 forum posts
997 photos


For thread size, see the neck-tube details, here: **LINK**



Which confirms Steve's measurements yes


Edited By Michael Gilligan on 18/12/2016 18:43:41

RICHARD GREEN 219/12/2016 11:22:59
324 forum posts
192 photos

Thanks everyone for your comments and help,

.75 pitch works out at about 33 tpi, perhaps I could run a 5/16 x 32 tap in the burner for about 1/2", and then use standard 5/16" x 32 pipe connectors,

What do you think ?


John Alexander Stewart19/12/2016 13:11:02
821 forum posts
56 photos

Hi Richard;

M8x0.75 - I purchased some metric fine taps from Tracy Tools - (no connection other than as a customer) - why not get the proper tap?

Just my opinion, for what its worth - John.

RICHARD GREEN 219/12/2016 15:20:58
324 forum posts
192 photos

Hello John,

I understand what you are saying, The burner is already threaded, my problem is getting fittings for the m8 x .75 thread in the burner,

I can get 5/16 x 32 fittings anywhere, off the shelf to fit 3/16" copper pipe.


John Alexander Stewart19/12/2016 17:04:21
821 forum posts
56 photos

Richard - Oh, ok. I make 100% (or, close to) of all my fittings, elbows, hex material etc, as it seems that nothing is off the shelf where I live, so pardon the myopia.

Good luck - John.

RICHARD GREEN 220/12/2016 16:11:38
324 forum posts
192 photos

What I've decided to do is, screwcut a brass screw in the lathe M8 x .75 pitch, and then make a "banjo" type fitting that can be silver soldered to the 3/16" copper gas pipe, the whole lot will then attach to the Primus burner,

Sound like a good idea ??...................................Or not,


duncan webster20/12/2016 17:52:26
3706 forum posts
69 photos

If it were mine I'd make up a barrel union with male M8*0.75 one end to fit the burner and 5/16*32 the other so you can use conventional nuts and olives. Of course you might not have room

RICHARD GREEN 221/12/2016 09:34:50
324 forum posts
192 photos

Hello Duncan,

I see what you are saying, unfortunately the burner sticks out quite a long way already as you can see in the following pictures, I would like to keep it all as short as I can, so the engine is as compact as possible, using an elbow or a banjo fitting will do that.


gardner and burner 001.jpg

gardner and burner 004.jpg

Alyn Foundry24/08/2020 13:50:35
8 forum posts

Hello Richard.

lovely work! I can confirm that the thread size is M8 by 0.75 mm pitch. I used to make a Brass Banjo coupling to convert to the readily available 3/16" Copper pipe sold for brake pipe repair. This also helped because Wade made many 3/16" compression fittings.

Cheers Graham.

Keith Hale24/08/2020 21:17:20
329 forum posts
1 photos


Concise and to the point.

Nothing more needs to be added.


JasonB25/08/2020 07:06:56
21999 forum posts
2539 photos
1 articles

Bit late to this old thread but you can also remove the stainless steel end to reveal a M10 x 0.75 thread so the burner end can be replaced with something shorter (or longer) too.

The actual jet 2nd from left is the only original part left on my IF Allman burner

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