Breaking-In Glow Plugs

I
Have heard of that but I was some other reason why the person did it but I don remember who it was or why.

Heat cycling a glow plug element allows it to anneal or helps put a set to the winding, taking out the winding stresses before it is subjected to the running stresses.

I have actually seen it written long ago on the back of an out-of-date glow plug package but understand it didn't stay long on the packaging because of the marketing backfire of making plugs last longer by doing this...hence selling less glow plugs.

I am also on a search of its origin but to no avail so far. I am thinking of it being a K&B plug package but cannot find much on vintage glow plug packages on the web.

Used to do this when I raced 1/8 scale offroad and were using $11.00 turbo plugs. Clip on the driver and just let it illuminate the coil, then immediately remove the driver and let the plug cool. Keep repeating allowing it to be lit just a bit longer. Did this about 6-7 times before installing in the motor for use. It seemed to help the life. The biggest thing is to not immediately flood the motor with a brand new plug on a first start try,,because then you could heat fowl the plug coil and shorten the life or make it a hard starter.

Ditto my experience when flying C/L stunt competition.

SD

SuperDave wrote:Ditto my experience when flying C/L stunt competition.

SD

Or you could put one in a microwave
Only kidding don't it will explode.

I haven't given up my search for the label I've seen that explains breaking in a glow plug.

The picture is a Cox package explaining how glow plugs get better with age (heat cycling as mentioned)

If there is a benefit i believe that it would "temper" the element for the life that it is about to endure.

Just a supposition.

SuperDave
Certificed Coxaholic

I wonder though if it doesn't have to do with the platinum being able to react as well as when "broken in" where it has to form pits or something for it to gain enough surface area to glow like it should with the methanol, transforms that way somehow...

In some 60 years of glo flying I have encountered no more than a handful of glo-plug failures. In fact I still have several CHAMPION glo-plugs that resemble spark plugs. (Remember them?)

I run them ocassionally just for show but NOT in inverted engines where they could easily be ruined in a hard landing "nose-over".

"Break-in" of glo's, to me, is an option and not an obsolute requirement.

SuperDave
Certified Coxaholic

SuperDave wrote:In some 60 years of glo flying I have encountered no more than a handful of glo-plug failures. In fact I still have several CHAMPION glo-plugs that resemble spark plugs. (Remember them?)

I run them ocassionally just for show but NOT in inverted engines where they could easily be ruined in a hard landing "nose-over".

"Break-in" of glo's, to me, is an option and not an obsolute requirement.

SuperDave
Certified Coxaholic

Me too a failure is very rare.

In fact I still have several CHAMPION glo-plugs that resemble spark plugs. (Remember them?)

SuperDave
Certified Coxaholic[/quote]

You "newbs" may have no experience with these CHAMPION glo's because they harken back to what you might consider "antiquity". They feature a white porcelin inset with the word "Champion" emblazed in red. They larger than today's glo's and quite distinctive in appearance. They often draw quite a bit of spector interest and comment.

SD

GermanBeez wrote:it would make sense because the glow plugs wont be exposed to the excessive heat of the combustion at their first glow, as the
wire probably never has been heated. thermal shock might actually make it more brittle and more liable to break.
it would also be a good way to burn off any oils or dirt left from the production, if there are any.

My high-compression COX glow heads sometimes burn out after a very few flights. The head deterioration starts with the platinum filament spiral getting distorted and touching the wall of the nest where it sits in the glow head thus short-circuiting a part of the spiral and effectively reducing the heat emmission when the battery is connected to it. I sometimes manage to realign with a needle/pin the spiral inside the well where it sits but it wont last for long.

Even after I add 1 or 2 more head gaskets to reduce compression and thus peak pressure and ignition temperature the filament is soon destroyed...

Any suggestion by someone on how to elongate the life of COX glow heads?

balogh wrote:

GermanBeez wrote:it would make sense because the glow plugs wont be exposed to the excessive heat of the combustion at their first glow, as the
wire probably never has been heated. thermal shock might actually make it more brittle and more liable to break.
it would also be a good way to burn off any oils or dirt left from the production, if there are any.

My high-compression COX glow heads sometimes burn out after a very few flights. The head deterioration starts with the platinum filament spiral getting distorted and touching the wall of the nest where it sits in the glow head thus short-circuiting a part of the spiral and effectively reducing the heat emmission when the battery is connected to it. I sometimes manage to realign with a needle/pin the spiral inside the well where it sits but it wont last for long.

Even after I add 1 or 2 more head gaskets to reduce compression and thus peak pressure and ignition temperature the filament is soon destroyed...

Any suggestion by someone on how to elongate the life of COX glow heads?

What Nitro percentages are you running? Are you running over-lean?

The freshness of the fuel has a lot to do with how long glow heads last. Water will super heat the glow element by pre-ignition.

Standard glow plugs don't see it that much but the Cox filiments are a much finer, hotter element.

Those high comp heads are a finicky little unit.

Some of them look distorted right out of the package.

Usually when you distort the coil it is extremely lean. It might run right when flying, but when you run out of fuel at the end of the tank, and it leans out and s-t-r-e-t-c-h!.

As you know, cold air is dense air. As a generality, your air/fuel ratio is in the lean side during the winter and the rich side during the summer.

PV Pilot wrote:As you know, cold air is dense air. As a generality, your air/fuel ratio is in the lean side during the winter and the rich side during the summer.

How do you cope with this?

Anything that will add extra heat.

Hotter glow plug.

Less nitro content,, make it more of a oil burner. Nitro carries it's own molecule of oxygen and with cold temps it's getting plenty of that.

Raise the compression/advance the timing.

On the really cold days, you could wrap the HEAD with insulating material/tape.

SuperDave wrote: In fact I still have several CHAMPION glo-plugs that resemble spark plugs. (Remember them?)
SD

Yup! These are Champion shorts bought new in the mid fifties. Champion stopped making them because they cost more to make than a spark plug when plugs were selling for about half a dollar.

George

gcb wrote:

SuperDave wrote: In fact I still have several CHAMPION glo-plugs that resemble spark plugs. (Remember them?)
SD

Yup! These are Champion shorts bought new in the mid fifties. Champion stopped making them because they cost more to make than a spark plug when plugs were selling for about half a dollar.

George

I want those! I remember seeing an ad for those in a old magazine!

You can get the modern version if you like.