Hi guys!

Has planned, I put a few hours aside today for testing my airboat. The big disapointment was the engine. It took everything to start it, but that probably comes from the fact that I haven't run a glow engine in the last twelve years... ( years really do fly!!!) Took me at least a half hour to get it to make single pops, then after a few more tries with different needle settings, finally it would run for 5-6 seconds and die[&o] the moment I cut power to the glow plug...

At one point I believed it was fine, since it ran without the glow driver, but it lasted for only a few seconds more and died again....Let me tell you that by now I was a really frustrated guy[:@]

I packed everything home and then tried to figure out what was wrong. I believe I might have a fuel flow problem, since I think the tank was not mounted properly. It's an old Perfect tank, made of metal, with 3 brass tubes coming out of it. 2 are close together, on the same side, and 1 on the opposite end( from the other 2). Does anyone know how this tank should be oriented??? I tried to remember how it was mounted in my glider ( 12 years ago) but my memory fails me!!!

Can somebody help me PLEASE????????

I was faced witht he exact same problem today. After changing the needle what seems like a thousand times. I chacked the plug, it would lite, fine out of the engine, but still I changed the plug just to make sure it was good, still same problem, so just for the fun of it, installed another new plug, then beleave it or not, All of the time it was 2 bad plugs, they would lite fine but would not stay hot under the load of the engine. Reset the needle back to where they should have been to start with and all is good.

Thanks Hal!!

I thought it might be the plug, so I checked it and lites fine...I'm still going to get a new a one just to get the variable out of the way.

But I still think that my tank is not properly positionned, I'm gonna try other orientations and see if it cures the problem.

Again, if anybody is familiar with Perfect metal tanks, let me know!!!

You can see it on my boat in the thread "boat pictures" if you look closely you'll see the 3 brass tubes( 2 connected together on the needle side of the picture, the other one with a 2" lenght of fuel tubing on the other side).

Thanks!

most tanks these days use 2 tubes. One for fuel pickup and one for pressure. You can have a third line for remote filling, but if you do then when you are running the engine this line needs to be plugged otherwise you lose fuel pressure. Most likely your engine will not even fire one stroke if you don't have the pickup line right. But if you are unsure fill the tank with water, or fuel if you wish, and connect some tubing to one of the brass tubes. Blow air into the tank. Whichever tube water(or fuel) comes out of, this is your fuel pickup line, if you hear bubble in the tank and no water is coming out of any of the tubes you are connected to the fuel pickup line. Now for the other two tubes, one is most likely for filling and one is for pressure. If you fill by removing the pickup line, than plug one of these tubes. If not then it doesn't matter which one you use for pressure and which one you use for filling. Position your tank behind your engine, with the bottom of the tank inline with the crankshaft. you can place about 1/2 inch lower or higher, any lower and you'll run into fuel draw problems, and higher you may run into flooding problems. As for the needle valve, my engine manual calls for opening it 2 full turns, and then tuning it from there. Tune your engine without the glow driver on it, it should be able to run at full throttle while running this rich, from there close the needle valve until engine hits peak rpm and starts to run too lean. Then open the valve 20-30 degrees. Once this is set never touch it again, unless you have huge humitity and temperature swings. Take the "if it ain't broken don't fix it", approach to setting the needle valve. If your engine dies as soon as you pull the glow driver, your plug may not be hot enough. Try using a "hotter" plug or one that has a fuel bar on it.

ludovic............having used PERFECT brand tanks many years ago, I think I can help.
The two tubes that are close together are the filler and overfloe tubes. The single tube coming out the side is the fuel pick-up tube.

First off try repositioning the tank. Put the boat in front of you, with the bow closest to you (the front) so you are looking at it straight on as if it were gonna run you over.

Now, position the tank so the TWO tubes that are together are pointed up and on the right side. That will put the pick-up tube on the right side also, pointing towards you.

With the G-Mark engine, you will not have any pressure line to deal with. The 2 tubes together are left in the breeze and the tank will work properly in this orientation.

Another thing to consider is the starting point of the needle valve. It may be set too lean, and will not draw in any/enough fuel to run.

Screw in the needle valve till it stops, then turn it out 3 FULL turns. This should be a good rich setting. It will run slowly when it starts, but it should get it going. Once it is warmed up for about 30 seconds, then you can slowly turn the needle in to get the max rpms. If there is some way to put a mark on the needle (a scratch will suffice) you can use this as a reference point for the # of turns.

what would the a best amount of turns to set my needle at on my .19 enya engine, and where can i get a cheap tuned pipe at,,, i would really like a new one sience it has the really gay flat black p.o.s. it comes stock with, it's loud and annoying because inorder to get to the motor mount i have to take the dumb thing off, [>:]

Hey guys!

Thanks for all your help! Pro I'm not surprised of your answer since you seem to be the 1/2a expert here They way you tell to orient the tank is the way I think it was mounted on the glider i don't know why I didn't think about that when i tried to run the engine When I was back home, I just went: Duhhhhh, we didn't I think of that earlier......So your experience confirms my thoughts and I'll try it this weekend. The glow plug has an idle bar i think it s ok that what I always used with that engine. I ll try the needle open 3 turns as you say...I tried at 2 turns open so probably that didn't help!!!

Again thanks to everybody and I'll let you know how it goes!!!

ludovic.......
The 3 of turns on the needle valve is a good starting point for almost any 1/2A engine. The use of an 'idle bar' glow plug may need it to be about a half turn richer to start. The purpose of the bar is to prevent the incoming fuel from hitting the glow element directly, as well as helping to retain heat in the coil when the engine is at an idle speed. Some engines tend to get drowned out at idle speeds for various reasons. If you are not using a throttle, it is not really necessary to use one. In fact, you may gain a few rpm's by replacing it with a standard plug. Personally, I like the FOX BLASTER short plugs.

Also, these small engines LOVE higher nitro fuel. 20% to 35% is the norm. The small engines also like some castor oil in the fuel blend. Yea.....varnish built up can be a pain at times, but at the rpm's these things turn, the only time you really need to worry about it is if you are storing (not running) the engine for a few months. BUt a good soaking in WD will usually clean it up pretty good.

My main experience has been with COX and Norvel engines in the 1/2A size. They COX engines are fun to tinker with. Performance can be changed dramatically just by using different head and cylinder combinations. Following are some pics of a couple hop-ups I have for the Cox.

This is a sleeve throttle. It fits certain styles of Cox cylinders. The cylinder fits in side this sleeve and is then screwed back into the crankcase. You position the two exhaust ports inline with the ports on the cylinder. The snap ring can be repositioned anywhere in a 360 degree area, which will have a wire pushrod hooked to it.

The way it works is when the ports in the sleeve and the cylinder are lined up, you have full throttle. By closing off the cylinder ports, by rotating the sleeve, you restrict the exhaust, thus providing some throttle control. It doesn't work as well as a carburator, but it does work.
It's a simple, basic exhaust throttle.

These are hard to find.

This is a throttle for a reed valve engine, like the Babe Bee, Golden Bee and Black Widow, that use the integral fuel tank.

It is basically a ground needle and backplate with a built in needle guide.

With the regular needle valve set on the engine, this second needle, controlled by a servo and wire hook up, closes and opens the intake venturi of the engine, which is located inside the fuel tank. This in effect, varies the amount of air allowed into the venturi. It acts just like a regular needle valve does, with the exception that it restrics the amount of air, rather than the amount of fuel.

Here is a GloBee head and insert.

What is unique, other than it's two piece design, is the higher compression it creates as well as the 'flat' glo coil. This was the 'must have' many years ago for all out speed and performance.

This last one is a standard Cox glow plug adapter.

In essence, it is a regular Cox glow head which has had the center drilled out, upper fins cut off and the hole threaded for a standard short plug.

It does not perform as well as a stock glow head as the procedure reduces compresion somewhat ( there is a trick to overcome that though), but is very handy for sport use and convient because it uses a regular glow plug which is MUCH cheaper to replace than a new head.

These were locally made a while back and sold thru a hobby shop in a neighboring town. The guy also made some for the Cox .09 as well as the .15 they made with the one-piece head and plug.

Wow Pro, you REALLY are the 1/2a expert!!!!

That little g mark is my only 1/2a size engine and I don't have any experience with the Cox products. I know higher nitro is best for those engines but man, they don't give it away....[]

I'm trying my own homebrew even if I know I'll loose a lot of power...but I'll see what happens!

Right now I'm in the planing phase of a .40 size boat for my O.S. .40 fp ( my only other engine).
The small one is more of a prototype of sorts, but I'm sure it will provide some fun when I run it!!!

Thanks for your help once again!!!
I'll let you know how it goes!!!

The nice thing about these small engines is that they are pretty miserly on fuel consumption. Running 25% nitro in mine, the 1oz tank gives me well over 10 minutes of run time.

Also, all the 1/2A blend fuels I have used are available in quarts, so the wallet doesn't get hit so hard. A quart of fuel will last quite a while. Yea, add it up and it is more expensive, but why but a gallon and have it go bad because you were not able to use it up? You're saving money right there.

What resources do you have for fuel availability?

does any one know where i can get a tuned pipe for my enya .19 engine, i cant find any one who makes then for this model, shoot i cant find a company that makes any thing that has to do with Enya, can anyone help me with this, i also need a nice motor mount,

Well, these are a little different, but I have used them and they work very well for sport use, as was their intention. They are a 'flat plate'type of pipe, not as critical on length as far as tuning, inexpensive as compared to other pipes, are made for a broader rpm range, less sensitive to needle settings and IMO very durable. Also, the only pipes out that to my knowledge that are made strictly for 'sport' engines, (ie; not race tuned ).

Check out the link....

http://www.flyquiet.com

Somewhere in one of the threads is a pic of one of my hulls with one mounted.

It's probably easier for me to just post the pics again instead of ya'll looking for them.
The harder thing to find will probably be an exhaust header for the Enya. If you can find a site that sells MAC products, they have the best out there, for a WIDE range of engines and reasonably priced.

I guess you might be able to try and accomadate one of those for the RC10 or Traxxas ( .21 ) ... if you are handy , you might be able to modify the header pipe to work and the pipe "should" work .
I am using one for a Megatech 16 and works good . ( using one for the 15 engines , just took my handy dandy drill and drilled the stinger a bit bigger in diameter . )

Hi Pro!

Fuel is available around here but the highest nitro I've seen is 15%, and it was sold only in gallons[]. The price is $30 can, wich I find kinda expensive...used to be half that price 10-12 years ago!!! I've looked and asked at lhs in my area and even if the guys know about the high nitro fuels for small engines, they say there is not enough demand for them to order it....[]

That's wy I'm trying my own FAI type homebrew, even though it's not the perfect solution for small engines.

Hopefully one day someone will invent a rc engine that runs on water!!!!!

You could always order direct! Shipping might be the costly thing though. Most 1/2A blend are available in pint and quart size containers.

Here are some sources to look at...

Tower Hobbies...Hobico 1/2A fuel
Sig Mfg...Norvel NVX & Sig Champion 25
Hobby People...AP-NFX
Powermaster...1/2A fuel in 3 blends

All these go for $9-$11 per quart. Yea, a gallon would be cheaper, but like I said, most would end up going to waste because you wouldn't be able to use it up in a relative amount of time before it would spoil due to moisture and such.

Hi Pro!

I haven't looked at the details of ordering direct, but your US$ price of 9 to 11$ becomes 12 to 14$can...then you must add shipping, customs taxes, federal taxes, fuel taxes(I'm sure they would apply...),sunshine taxes, color of your underwear taxes ( we have taxes for everything in Canada....) and I'm sure it would not be economical anymore...

If I can find a replacement here, be it lower nitro or homebrewed, I admit I'd rather give my money to a local business, either lhs or other. I admit you guys in the states are blessed with more variety wich is good but only comes if there is a big enough market! To give you an example, I ordered once a knife blade to make a bowie knife. Impossible to find it in Canada. A catalog company sold one for the very reasonnable price of 20$US...cost me 3 times that amount in can$ when I finally got it!!!!

I guess I'll have to do with what I find...

Question: what do you think of a .20fp to repower my boat? I came accross an ad for a used one, guy says he only broke it in, and I'm sure I could deal it. I haven't run my boat yet, but I have real doubts about the power of my 0.061...would a .20 be overkill??? For ref, the boat is 18x8x1.5 and weights a hair over 1.5 lbs, rtr. Thanks!

See ya!

No .... wouldn't be overkill ... actually would be just about right

I'd have to disagree with you there Terbo......

The .20 would stand a good chance of tearing that little hull apart, as well as not being able to keep it on the water.

The G-Mark .06 should move that little hull to around 15mph. If you want more power, but still be able to control it, I'd move up to an .09 or .10. That in itself would make this size hull a little water rocket. I generally limit hull size with an .10 to around 18"-22" (shortest to longest length).
The beam at 8" to my experience MAY BE a little narrow, but would be workable.

If I remember right, this is a balsa hulled boat ?

IMO and experience with these small airboats, a .20 is too much power. Those dimensions are better suited for 1/2a to .10 size engines.

LUDOVIC ,
Don't listen to Mark , he doesn't know a thing about the little boats , he only does the BIG ones .. ( yeah right --- )
Actually , you better have known I was joking ...
PRO is the man when it comes to those littler guys .... ( I wonder if thats why he goes by PRO ? )
Seriously though ... when it comes to the smaller N's motors , I would take his word to the bank ...

just a question, what does iom mean???????