Re: Running in a Tee Dee with 0% nitro. Wowzer, I found the right combo and it sings a beautiful song now!

SuperDave Wed Dec 26, 2012 10:51 am

Ceramic engine component's priciple advantage is lighter weight which allows today's engines to create more power, better MPG with smaller displacement engines.

i.e.: The 5.0 liter Mustang over the modern Mustangs. (Camero's too I admit grudingly.

Wink

**RknRusty** Sat Dec 29, 2012 9:38 pm

After a few break-in runs of this Tee Dee with 3oz of 0% nitro and then 2oz of 24% nitro, I devarnished it(it was a little brown inside) and got it ready for a full out test run. The other day, while I was ordering a quart of Glowplugboy 24%, I decided, what the hell, lets get some hot stuff too and see what this new Tee Dee will do. So I ordered a quart of Sig Champion 35% and it came today. Last year I gave up on Sig fuel because it was turning my glow elements frosty white and impotent. But nobody else has heard of that so I thought it was worth another try, especially since all I run anymore are Tee Dees and Norvels.

I added a couple of drops of Armor-All to the Sig because it foamed a lot when I shook the bottle. Then I washed out the tank with methanol and filled it and lit her up. It ran great in the mid 20k range. I pinched off the fuel and swapped props just to see how it liked different loads but then it wouldn't even pop or crank. I had blown one of my last three Cox 1702 heads, one of which is very old and suspect already. The other one is still on the Streak. Damn! I forgot about needing a third shim for the 35% fuel. I added a shim and put the last old 1702 head on it, the old beat up one, and gave it another run. It ran fine. Neither element was discolored after running, so hopefully that was just some bad fuel I had last year.

I suppose the reason that plug blew was from too much compression. Luckily I have some spare Merlin and Norvel insert type plugs that will work and I'll probably be using those from now on since my Cox heads are dying off. I have a Galbreath clamp and one Nelson plug too. I hate to see the end of my old Cox heads, but so it goes. They ain't worth the bucks anymore, and the Norvel and Merlins work fine.

Anyone ever blown a plug because of only two shims with 35% fuel?

Surfer_kris Sun Dec 30, 2012 6:28 am

Most likely it was over compressed, but why use armor-all in the fuel? It contains silicon oils (I guess, I have ever seen a contents declaration) and that could potentially damage the plug.

I don't know who came up with that odd idea of adding armour-all to engine fuel, it is meant for the outside of a car, not inside the engine (!). A bit of bubbles on top of the fuel will not do any harm, that's only air surrounded by a very thin film of fuel.

Ken Cook Sun Dec 30, 2012 6:43 am

Adding Armor All was something I suggested to try. We use it all the time and although some claim it will do apparent damage to your plugs, I have yet to see it. I made mention of this to Bob (Fit90) as he was running a R/C bird that was just suffering badly from fuel foaming and the vibes would kill the rpm's off. I suggested a squirt into the fuel can. I can't take credit for this as I didn't discover it. I'm just passing on what I've seen work. Armor All works absolutely wonderful in the fuel. It takes only a small drop or two as Rusty stated.

The white frost as Rusty explains is something that's quite apparent and I feel that it's just unavoidable. That white frosty stuff grows on the elements of the plug. It's not a result of using Armor All as some may think. Maybe this white stuff is just a by product of combustion? Who knows, but Larry Renger (former Cox engineer) talks about this all the time and this happens with every plug he uses as well and he makes reference to this as white taters. He recently posted on the stunt forums how he was using muriatic acid in a eyedropper to remove this deposit. I see it happen on many of my Norvel plugs usually ones that have some time on them. It generally attacks the first set of lower coils hampering the glow of the plugs.

A small simple test in a plastic jug will show you exactly my findings. Take your fuel and shake the bottle and watch the foaming, let the bubbles settle and place a drop of Armor All in the jug and try again and you can witness first hand that not one bubble will take place. This helps tremendously with profiles that we fly in control line. I keep it in my pit box and nowadays is a prerequisite to a new gallon of fuel. Ken

Surfer_kris Sun Dec 30, 2012 6:51 am

I know you didn't invent using armor-all as a foam reducer, I just wonder where it comes from in the first place. It just seem like such an odd idea to me, the risk is far higher than any possible gain, as I see it.

A few bubbles on top of the fuel cannot do any damage, that's just air anyway. There is (or has been at least) a movie on youtube that shows what really goes on inside a tank during flight. The real problem is that the fuel goes all over the place, but there are no bubbles in the fuel it self.

Ken Cook Sun Dec 30, 2012 7:06 am

I meant that I didn't invent the idea of using it in the fuel. In fact, I wonder how in heck someone even accidentally thought of it. I just don't know. I do know that on profiles you can't set the needle on the ground due to the fuel foaming from vibrations giving you a false needle setting. In fact on a model that is shaking like that, we sometimes even have to isolate the tank with our hand trying not to squeeze the tank due to it wanting to richen the mixture as well. You need to hold the nose firmly and also tank to set the needle. Sometimes picking the plane up off it's gear is also required. Hopefully after a lap or two the engine settles down. In the case of a Fox.35, this isn't always the situation as some can just shake the bejeezus out of the plane to the point the Monokote is harmonically resonating. Placing the Armor All in the fuel will almost cure this problem.

In terms of some not liking that product in the fuel, I can only add this. We don't like having dirt in our fuel either. It happens, and it can enter our engines in numerous ways. I find contaminants such as dirt far greater of a threat than one or two drops of Armor All. This is certainly a simple test and just something to try.

The only real cure to the dreaded vibes is a plastic hard tank with a bladder tank inside of it. The hard tank is suctioned with the syringe removing all air prior to filling. The fill line is then clipped just like a bladder so air can't enter the tank. Muffler pressure inflates the bladder tank inside the hard tank displacing the air within the hard tank keeping a steady head pressure on the fuel load. Tetra is one manufacturer of these types of tanks. It takes a bit of extra starting procedures, but it has allowed some of my problematic models to be useable once again. Ken

Surfer_kris Sun Dec 30, 2012 7:19 am

Yes, the Tettra bubbles tanks are good, while "Tetra" is a swedish company that makes containers for milk. Wink

**RknRusty** Sun Dec 30, 2012 10:38 am

I didn't even add enough to completely stop the foaming, but it reduced it a lot. I was surprised at how much foam formed when i shook it and it took more that 20 seconds to settle. Since I was using it in a Dubro tank on the stand I figured I'd give it a try. I've never done it before, but I figured since others were swearing by it, I would take the risk.

I did flood the engine before it cranked the first time, so over compression is probably what popped the plug. The element is still connected, but the ohm meter reads no continuity.

For the last run on the stand, I'm going to switch to a bladder and the KK NVA and put one of the Merlin heads on it. Even with balanced props and 35% fuel on suction I don't see the kind of RPMs my .051 runs. With 3 shims and the old 1702 head it was turning 19.3k with an MA 5x3. 20.3k with an APC 5.5x2.5. The new plug might pick it up some. Maybe the new cylinder still needs some breaking in. But anyway it's plenty strong enough for a Li'l Satan.

Surfer_kris Sun Dec 30, 2012 12:04 pm

Have you checked the piston "height" at TDC?
(it should be level with the sealing surface for the head)

This can vary between engines and if it is too high, relative to the cylinder, you can put shims below the cylinder to raise it. It will not only affect the amount SPI, but also the timing and compression ratio.

**RknRusty** Sun Dec 30, 2012 2:07 pm

Kris, I have eyeballed it but it deserves a closer look. I'll check when I swap heads this evening.

**RknRusty** Sun Dec 30, 2012 6:44 pm

It looks like the piston is level with the deck with no shims. I put three in it with a Merlin head and a new plug, put the KK NVA on it and made a fresh bladder and took it out to crank with the Sig 35. It was cold for here, but above 40, and it was stubborn. After 354 flips I finally got it running and it cruised at 20.5k. I'm used to my .051 cranking in one or two flips, but once running it never wavered until the bladder was almost empty, so it's ready to fly. I might experiment with different size venturi bores. I've always been conservative and kept them about .130". I' may try some larger holes up to .156(5/32") which is what the Tee Dee manual suggests, iirc.

THE WEATHER HERE SUCKS!

Surfer_kris Sun Dec 30, 2012 8:51 pm

That sounds good to me. It will never run as smooth and stable as a Norvel engine, there is something about that ceramic techn. and tight seal that makes them run well even if they are a little on the lean side on occasions.

**RknRusty** Tue Jan 01, 2013 10:27 pm

I bored the venturi out to .1406"(9/32), one size less than the TD manual suggests, but more than the .130 I've been using. And one of Bernies Merlin head clamps and plugs with 4 shims. It was easy to crank and rock steady at 20.5k with a Tornado 5.5x3 prop on a bladder. It goes back on the Satan now and I can't wait to fly it.

The only glitch is when I unscrewed the old engine from the radial backplate mounted to the firewall, the new one tightens in a different position. The other one tightened with the cylinder straight up and the needle out to the side where it's safe. The new one is cockeyed with the cylinder off at an angle toward the outboard side and the needle opposite. I have blind nuts behind the firewall and 2-56 machine screws to mount it, and no other alignment of the holes makes it better. So that's the way it stays. I've seen one of Surfer Kris's mounted like that, so if it's good enough for Kris, it must be good enough for me.

Ken Cook Tue Jan 01, 2013 11:08 pm

Rusty, if needed you can lap the back of the case in the same fashion most true up the reedie cases. Doing a little at time would probably place your cylinder upright as it sounds like you only need to go a touch. It's not as if you need to go all the way around to clock your cylinder at 12 o'clock. I do this many times just insure a nice seal on the stock backplate. Ken

John Goddard Wed Jan 02, 2013 1:28 am

My tuppence worth...
I probably fly more than most being a club instructor.
I'm very fortunate in that fuel wise I'm a distributor
For Optifuel which is for my aerobatic and 3d stuff and
I live 35 miles from Southern Model Craft where Dave
(bless him) mixes any castor blend the day I pick it up.
Point I make is fresh and just as importantly unadulterated
Fuel.
When I first returned to this Cox monkey business 15
Months ago I bought some fuel from a shop and it had lots
Of issues such as hard starting, horrible sludgy exhaust residue
And deposits on plugs.
Since that tin of 'old spunky's back room back shelf sh*te' as I
Now think of it went in the dustbin my Cox's have been superb.
No deposits, no wonky starting and some of you have seen my
Utubes of fairly impressive revs with straight from the box
Engines.
I think some of you guys need to sort your fuel supplys/suppliers
Out, from where I'm sitting so many of the issues that pop up
On this forum are fuel (ie bad fuel) related.
As for foaming I'm lead to believe it's the castor that foams
Why not try a castor/synthetic fuel mix?

**RknRusty** Wed Jan 02, 2013 3:49 am

Ken Cook wrote: Rusty, if needed you can lap the back of the case in the same fashion most true up the reedie cases....

That occurred to me too. The reason I didn't do it right off is because of the clearance, or lack thereof between the crank pin and the facing of the backplate. Of course if that were an issue, I suppose there's enough metal there to remove a tad of its thickness. Thanks for the tip.

John, that's a good point about fuel. I have had suspect juice in the past. The Sig I'm using now is half Klotz synthetic. Much more slippery than pure castor. Assuming it's a good batch I think the synthetic improves RPM too.

I'm really happy I found this little engine's sweet spot. When the days get hotter I might remove a head shim to see how she likes it. But not now, because it popped another glow plug when I was testing it with three. I think it was due to my inept flooding, but it sure was harder to crank with 3 in the cool weather. It's a one or two flipper the way it is now. Meanwhile I'm going to try this venturi on the Streak's engine and see if it gets a boost.

Ken Cook Wed Jan 02, 2013 4:58 am

I'm not suggesting it couldn't be an issue, but I doubt it would be as there typically is sufficient room behind the rod and the rear cover doesn't hold the rod on the pin. It enables the rod to float. Removing the cylinder while the engine is mounted on the plane will allow you to look into the case and see how much room is left. My thoughts are if the one engine worked, I see no reasoning why the other wouldn't. I have used o-rings as well which could also help. Ken

iskandar taib Thu Jan 03, 2013 8:12 pm

Small quibble. F2D Combat fuel is supposed to be 10% nitro + 20% castor oil. Some Europeans (particularly in the East) do use no nitro fuel, but nitro containing fuels are readily available in the Western Europe from RC suppliers. And high nitro fuels can be mixed from car fuels.

I suppose the approach to get reliable runs from low nitro fuel would be to increase compression. When I was in school the local RC fliers used to mix their own no-nitro fuel, and since it was so much cheaper than Cox fuel we naturally tried it in our Black Widows and Babe Bees. It worked IF you used a 1702 head.

Incidentally, the trick to getting fast starts with a 1702 head was to use a 2V battery. The element is a little thick for 1.5V. The people who flew 1/2-A combat knew this, they'd bring a Cyclon cell to the field and use it to start Tee Dees only (and used something else for the big engines).

About Armor-all. There is such a thing as too much. Once, at a combat contest, I put in a squirt into into my quart fuel jug. After that, I couldn't get the fuel tubing to stay on the needle valve! It would slip off a few seconds after launch. After 2-3 incidents I used a cable tie to keep it there. I had to take emery paper to that needle valve's fuel nipple to ever get tubing to stay on again.

Iskandar

**RknRusty** Thu Jan 03, 2013 11:32 pm

I used some 600 and then 1000 sandpaper to knock a little off the back. No clearance problem, but I did take slightly too much off for the engine position. Yeah, I'm a dufus. Some Teflon tape carefully trimmed and wrapped around the threads tightened it up in about the right place. It shouldn't have to be super tight as the direction of torque will keep it snug. The Li'l Satan is all back together and ready to fly again.

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Running in a Tee Dee with 0% nitro. Wowzer, I found the right combo and it sings a beautiful song now!