propjobbill

I need help with a glow plug. I am running a K&B stallion .35. It starts right up and has great rpm’s but as soon as I remove the glow clip if will run for about 15 seconds and then die. As long as I keep power to the glow plug it works. I have tried different plugs most are in the hot range. What hind of plug, or what are your suggestions?

cutaway

How much nitro is in your fuel?

The Stallion was a sturdy but unremarkable performer designed for the sport market where 10% nitro and a medium heat range plug like a Fox "standard" would be the norm.

Other than being a tad on the heavy side, they're usually a decent engine.

Cyclic Hardover

My Feedback: (3)

Sounds like you need a new plug

build light

Do your plugs have an idle bar?
I remember quite well when I bought my first "big" engine which was a Stallion .35. Since the new engine did not come with a plug I also had to have one of those as well. The LHS owner made sure that I understood glow plugs for this engine were to be the "non R/C" or no idle bar type glow plug.


Robert

downunder

I can't remember now what plug I used in mine but for sure it wasn't anything fancy, most likely a Taipan red because that's mainly what we used back then. I suspect it's more likely you've got a fuel problem seeing you've tried other plugs. I ran mine on zero nitro 25% all castor and it ran great in a Count Clipper combat model.

propjobbill

I have tried fireball hot plugs that have no idle bars. I also tried two different glow plugs with idle bars, but I don't know what brand or heat range they were. I have always used the fireball hot reg. plugs with great results. This is a new to me used engine, maybe it is some other problem. But it works fine until I pull the plug wire. I have tried 3 different plugs with the same results. So maybe there is some other problem.

After it dies I can reconnect the plug wire flip it and it starts right up, but once I remove the plug wire it will run for a short while and die. I am running it at full speed for control line. It runs great but before I can pick up the handle it dies. I tried it atleast 12 times. I thought maybe something was lose in the heater filiment, but I can't imagine it happening to every plug I put in.

Thanks for the imput

propjobbill

I just did a test run in the garage with a cold heat range plug, and it ran for atleast 2 minutes until I pinched the line to stop it from running. I won't be able to fly until Sunday or maybe Monday, but it seems to be working with the cold plug.

Is it possible that engines run better with cold plugs? I have always used standard or hot plugs because the cold plugs take a longer time to heat up with a glow driver.

If you have found that cold plugs work better let me know. I was told that cold plugs were for very high proformance engines. These K & B engines are of the sport line. I still have one I bought new for $6.95 over 35 years ago. Its been run four or five gallons or more, and still runs great, but not real powerful.

da Rock

I didn't see you mention your fuel.

The amount of oil matters as does the amount of nitro.

Cold plugs are needed for high nitro fuel. Hot plugs are needed for cold burning fuel (need to keep their own heat). When a plug doesn't match the heat of combustion AND the engine is a sensitive one to timing you might have needle setting problems.

BTW, the heat range of the plug often changes when the combustion starts. That changes the timing of the event. Change the timing and they often act up.

What is your fuel?

Also, have you pulled the head of that engine? Did it have any headgaskets? Lots of the old ones did. Some would have as many as 3. They adjusted the mfg tolerances of the day with headgaskets sometimes. Changing the number of headgaskets changes the compression which also changes the timing.

ifr2lax

PropJob,

STOP...I doubt if the glow plug or nitro is your problem...I will guess you are overheating and seizing due to low total castor oil and WAY TOO lean a needle setting.

1. What fuel are you running?

The older 50's to 60's basic engine designs set up with iron piston/steel sleeve construction and plain bushing crank like the K&B Stallion 35, Fox 35, McCoy 35, etc MUST HAVE at a minimum 25% CASTOR OIL fuel...1% synthetic MAX if at all.

MODERN engines like a "OS LA" have a aluminum piston and brass sleeve...they run FINE on lower total oil, 18 to 22%, and a 50/50 synthetic oil to castor mix.

Find some Fox Superfuel...29% castor oil or Sig Champion 25% castor...just so it is ALL castor and over 25%. Do not sweat the nitro...5 to 10 % is fine. Think OIL!
The really low oil fuels are for the ball bearing crankshaft engines that have modern piston/sleeves

2. If you set your needle valve to a screaming, shrieiking, FULL LEAN on the ground, the engine will overheat in short order...if you even get it in the air on the "low oil" fuel I suspect you are using it will be a toasted compression-less paperweight soon.

When the engine is in flite, it speeds up as it unloads and the mixture then gets leaner...SIZZZZLE..!

CASTOR OIL gets THICKER as it gets hot...but, synthetic oil evaporates...ie: an overheating engine with CASTOR will get gummy as the castor oil DRAGS it down and deposits a protective, if messy, layer of varnish on the piston, sleeve, and crank bush.

However, synthetic oil just burns and goes away...very clean...but, you will have a worthless lump of ruined engine left over. But, very clean.

Final thoughts...

Get the correct fuel for the engine, BREAK the ENGINE IN????, and always back off the needle from a full screamin' peak RPM.

Once the engine is broken in, go to peak power if you have to, and back off, ie: enrichen the mixture a 1/2 turn...it should hold that setting in flite...if not, you are likely ruining the engine.

Have fun with the old engines. Break in is a whole other story in its self for the old type engines.

Pete

propjobbill

The nitro is at 10% with 29% caster oil, I back the needle out until it is about to 4 cycle It does lean out in the air. I've never had an engine act like this one does. It has reasonable compression and good rpm. Today I got a couple of flights out of it, but I was not pleased with the way the engine ran. I will spend some time in the next few days trying to find out what is wrong with the engine. It will run with a cold plug, but not with a hot plug. I've had Enya's that needed cold plugs but this is the first K & B Stallion that I've owned that wouldn't work with a hot plug. I am going to order more plugs, I think I will order O S #3 and #8 and some kind of a cold plug and test them all out.

Ive had a good bit of feedback between here and another forum so I think I will waite until I get new plugs and try some different fuels I have 10% nitro with 29% caster oil, and I have 10% with 20% mixed blend I also have much hotter fuels 25% and 40% but I won't run anything more that 10% to 15%. If this engine continues to be a problem I will retire it and go on to a different engine.

Thanks for the help

cutaway

I've had two Stallions and they both ran fine with a standard long Fox plug and fuel that I mixed myself approximating the mix you described. I was probably at 25% on the castor rather than 29% though. Basic stuff, nothing fancy. Castor, nitro, methanol.

lukesp

Perhaps you have a varnishing problem? I know that my engines will display erratic running behaviour when there is a sufficient varnish buildup on the piston and liner.

Strat2003

My Feedback: (1)

Take a close look at the element in your plug. Is it shiny and silver, or sort of frosty-white looking? Maybe a little rough and bumpy rather than smooth? Sometimes plugs get coated with something (I've heard silicone, which becomes silica, or glass) that keeps the platinum in the element from reacting with the methanol in the fuel. That catalytic reaction helps keep the plug glowing when you remove the batterey. If it doesn't take place, running becomes iffy without the heater.

gcb

One last guess. Have you checked all the gaskets for leaks? Head gasket, backplate, glow plug? Perhaps something is warping when it's in the air, causing a small leak.

George

propjobbill

Thanks for all of this good advice, and suggestions. I have tested the engine with new hot glow plugs and I have had the same results. When I pull the plug wire the engine dies. But when I use a cold plug it runs fine. Ive ordered one dozen cold, one dozen medium, and a few hot plugs that should be coming in in the next few days.

Other than the hot plugs that I now have all the other plugs are out of other engines so I can't say for sure what range they are. I know that some of them will glow bright as soon as I apply power and those are hot. I have a few that were cold plugs as best I can remember, because they are no longer in their package. I use a power panel and those pluge need a lot of power for several seconds before the will begin to glow dull red. But those are the plugs that will work in this engine. Once I start the engine with those plugs it keeps running. I tested out about 8 or 10 old engines monday and found that some of them worked with the cold plugs, and some worked with hot plugs.

I did notice that with the hot plugs the engine did a lot more kicking back, and even tried to run backwards until it would backfire and then run forwards. I could never get it to run more than 20 seconds without a plug wire attached. With this K & B Stallion even with a cold plug it runs but , when I fly the plane it runs uneven sometimes speeding up or slowing down.

When I get the plugs in that I ordered I am going to test the engines again. I knew that some engines preferred cold plugs. But this was the first time I had ever had to use a cold plug on a K & B Stallion just to keep it running. I have tried to test the engine for leaking gaskets. I don't have any new gaskets, but a made one of tin foil, and also used a gasket forming material that was good to 700+ degrees. I don't think it is the gasket but I cant say for sure.

Thanks

qwerty3

Sounds to me like bad fuel - that has somehow taken on water. I'd try a fresh jug of fuel, and see if that makes any difference.

cutaway

I just broke in a brand NOS Stallion on the stand this week. Standard Fox long worked fine.

Curiously, the backplate screws worked loose after about a quart through it and needed re tightening. It acted a little funny with all that leakage in the case when the cover was loose...but it actually stayed running.