Glow Plug for the G-Mark 03

1/2A Nut wrote:You will have to drill and tap the existing glow plug for a standard plug.
There are no vendors selling the replacement glow plugs any more.
I have about 6 glow plugs for the .030 enough to last many flights.

Thanks Brad for the information, do you know the procedure or is there somewhere on the web where it shows how the modification is made?

Matt sells this tap could be for the cylinder. "Cox .049 Cylinder & Glow Head Tap"
Think this is for the cylinder top and crankcase.

I tapped one of my cox glow plugs back in the 1980's it was easy to do.

http://www.exmodelengines.com/product.php?productid=18106&cat=258&page=1

17/32-40 Thread not sure what this fits the description is vague.  




here you need this:
https://www.towerhobbies.com/cgi-bin/wti0001p?&I=HIGR1100&P=FR&atrkid=V3ADW3A24148B_45992359586_pla-302478605406__221282308788_g_c_pla_with_promotion__1o1&gclid=EAIaIQobChMI_-f3ysSJ2QIVhbXACh3ajgXIEAQYASABEgLEkvD_BwE

1/2A Nut wrote:Matt sells the tap, I tapped one of my cox glow plugs back in the 1980's it was easy to do.

http://www.exmodelengines.com/product.php?productid=18106&cat=258&page=1

17/32-40 Thread  perhaps you can do a search to find a tap that size in your country?

Well, what is the glow plug that I should use ?, that is, what is the thread that threatens there?

read my post again I have more info now, did you buy a GMark .030?

1/2A Nut wrote:read my post again I have more info now, did you buy a GMark .030?

No, not yet, but there is a possibility ...

What this one?

https://www.ebay.com/itm/VINTAGE-G-MARK-03-RC-MODEL-MOTOR-AIRPLANE-CONTROL-LINE-TETHER-NEW-IN-BOX/323037577029?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

I like the black backplates over using the fuel tank.

1/2A Nut wrote:What this one?

https://www.ebay.com/itm/VINTAGE-G-MARK-03-RC-MODEL-MOTOR-AIRPLANE-CONTROL-LINE-TETHER-NEW-IN-BOX/323037577029?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

I like the black backplates over using the fuel tank.

Yes, that same one was in the crosshairs ...

Best wishes on the hunt!

Here are my 4 shows a bit more of the back plate you could make one out of aluminum.
Which would be a good thing as these engines run a bit hot and need  22% castor in the fuel
blend to help them run cool. 45% nitro will help them run cooler too.







AmpAbuser
Published on Jan 20, 2018

G-Mark .030 stock prop 115Mx50M 17,280rpm
Engine has SPI removed muffler / rare stock prop: 115M x 50M / 4.53x1.97
Static 17,280 Best Peak / 5.64oz thrust / .062hp / 46.3W / 66mph
Average: 16,818 per laser tachometer
New old stock engine was still a bit rich not quite holding a steady peak I would imagine best peak after some field flying around 17.4K / 25% nitro / 20% castor / no effort was made to adjust for best low idle.

1/2A Nut wrote:Best wishes on the hunt!

Here are my 4 shows a bit more of the back plate you could make one out of aluminum.
Which would be a good thing as these engines run a bit hot and need  22% castor in the fuel
blend to help them run cool. 45% nitro will help them run cooler too.

thank you friend! ..... ohhh you have a handful there ... congratulations!

Tapping for a regular glow plug would simply rob too much power on these small engines. A turbo plug is the only viable option if you want to modify a stock head, or make one from scratch. I still have a few spare stock heads so I haven't tried to make any turbo head for any of mine yet, but it was doable on both the cox .020 and the VA .020, so I guess there will be enough room on the G-mark .030 too.

Spare parts do tend to pop up every now and then, so if you just keep your eyes open, you'll likely find some. I recently scored 3 NIP front ends for the G-mark .030 that where not properly identified in the ad for them. As the front ends tend to wear out around the carb, this will help to keep my engines running for a bit longer.

Are you talking about the plastic carb bodies?
He has never made a plug adapter. If he only has one plug to work with a turbo
plug would be best, but a tall order without assistance. Perhaps you can send
him the link on RCU showing how it's done. Or lathe a few from scratch and send
me one as well. The .03 may be big enough to handle a Nelson plug.

Could do with 3 cooling fins the stock plug does very little to aid in cooling.
On Ebay all I ever see is the engines never any spare plugs.

Yes I should have 3 NIP plastic carb bodies or their way here, I hope...

What is the thread size of the head on the G-mark .03 engine?

The easiest option is perhaps to use an old head as a clamp ring and machine a Norvel head insert for it. AndyW (on RCU) did some a bout ten years ago;

Just checked the threads, it might be an M11x0.5 thread and they one could quite easily get a dye and make a new head and/or clamp ring without sacrificing any heads.

Surfer_kris wrote:Yes I should have 3 NIP plastic carb bodies or their way here, I hope...

What is the thread size of the head on the G-mark .03 engine?

The easiest option is perhaps to use an old head as a clamp ring and machine a Norvel head insert for it. AndyW (on RCU) did some a bout ten years ago;

All this information is very interesting and can definitely solve the problem of the glow plug.
Do you have a video to see him work with that reform?
Thank you....

I don't know how well it worked out, but it shows what one can play with and have a much better chance at success than just tapping for a regular plug.

On the VA .020 I made a new clamp ring and an insert with the Turbo plug. That head thread was an M12 though, so there is less room to work with on the G-mark. One might simply have to make a whole head rather than a clamp ring and insert. The insert is much faster to make to so it is easier to try a few different designs without having to make the threaded part and the cooling fins every time.

Here are two pictures of the VA .020 head again, as a reminder of what it looked like (stock clamp-ring and head to the left):

That turned out great Kris! Any new data numbers yet?

I like the Nelson Turbo plug the element hole made for the 1/2A class is smaller.
The plug with the notch marks.

The Nelson plugs have a larger thread, I don't think it will be possible to fit those to the G-mark .03. Merlin makes a Glow-bee style Turbo plug that will eliminate the whole completely. I've made a few test runs with it only, and most engines will need quite a few extra head shims to get back to a correct compression setting.

I've only tacked the VA .020 on the bench, I haven't flow it yet. It makes around 18800rpm on the regular 4.5x2 cox prop, with 10% nitro and a rough muffler. So about comparable to a good TD .020 with an unrestricted exhaust. The VA might have more of an advantage on smaller props than that, but I haven't tried it. I'm more interested in getting a good RC engine, and I started making an RC carb for the VA, but it is quite time consuming to do and I got sidetrack with other things...

Here are some picture of the "glow-bee" style Turbo plug by Merlin:

Yes maybe too tight to fit a Nelson I have not measured.
The Glowbee plugs have the advantage of no element hole
to loose compression and keep the power mix in the sweet
spot. I have found the Glowbee elements are thirsty for amps.
I use a 12v voltage regulator variable from 1.4 to 2v so viable.
The element needs more study on my end I have always concidered
them cold in nature when the engine is running. The physical nature
of the open flat coil has the gauge a bit much I feel.

All this talking made me a bit curious to see if one can make a turbo-plug head for it.

It turns out to be quite easily actually. A one piece head shouldn't be any problem and there is just enough space for a "head and clamp" style. I tried to make one with a bit of a squish band, as I have done on larger engines. This first try actually turned out to be a little on the high compression side, with one head gasket, so another head gasket or two should be fine I think. I gave it a quick run on 10% fuel and it spins right up to a nice song.

Here I intended to post a few images too, but it doesn't work, I just get a blank empty window....

Another go at posting images from another host:
(nope that didn't work either)




Here are some links instead, if you click on these the image should open up in a new tab:
IMG_2267.jpg
IMG_2274.jpg
IMG_2272.jpg

Looks good Kris certainly viable solution to keep them up and running.

Surfer_kris wrote:All this talking made me a bit curious to see if one can make a turbo-plug head for it.

It turns out to be quite easily actually. A one piece head shouldn't be any problem and there is just enough space for a "head and clamp" style. I tried to make one with a bit of a squish band, as I have done on larger engines. This first try actually turned out to be a little on the high compression side, with one head gasket, so another head gasket or two should be fine I think. I gave it a quick run on 10% fuel and it spins right up to a nice song.

Here I intended to post a few images too, but it doesn't work, I just get a blank empty window....

Another go at posting images from another host:
(nope that didn't work either)




Here are some links instead, if you click on these the image should open up in a new tab:
IMG_2267.jpg
IMG_2274.jpg
IMG_2272.jpg

What a good job you have done Kris !, if you need, you would make this option to sell ?, actually I only have a glow plug and it is the own engine.
I would be happy to have some alternative to enjoy the engine!

I am not in any position where I can produce these heads an sell. I'm just a hobbyist with a small hobby lathe...

It would take someone like Galbreath or Valentine, I guess. But Valentine has closed shop and now possibly Galbreath too?

I could possibly make an extra head or two, for someone desperate, but first I need to tach this one and compare it to the stock head numbers. I was showing this mainly to illustrate that anyone with access to a lathe can make these heads fairly easily. It is actually quite satisfactory to be able to make heads for different engines. It extends the life of a few engines with special heads (like the Webra 1.8cc for instance) and in other cases it can give a power boost over a stock head with a regular plug.

Surfer_kris wrote:I am not in any position where I can produce these heads an sell. I'm just a hobbyist with a small hobby lathe...

It would take someone like Galbreath or Valentine, I guess. But Valentine has closed shop and now possibly Galbreath too?

I could possibly make an extra head or two, for someone desperate, but first I need to tach this one and compare it to the stock head numbers. I was showing this mainly to illustrate that anyone with access to a lathe can make these heads fairly easily. It is actually quite satisfactory to be able to make heads for different engines. It extends the life of a few engines with special heads (like the Webra 1.8cc for instance) and in other cases it can give a power boost over a stock head with a regular plug.

OK, I understand that you do it as a hobby, I do not have a lathe and here it is difficult for me to make any of these pieces.
If one day you decide to do some extra, I would be very good, with only one that I can use a glow plug standard turbo type, I could enjoy the engine with peace of mind.
I write down the list for that matter :-)