Re: Needle Setting For Cox Engine With Fine Thread Needle

[RknRusty]

That thing has a long needle on it. Remove it and see if it looks like the threads have been worn down or smoothed out. I had two engines just like that one(except mylar reeds)on my Bats with the yellow plastic(Nyrod) extensions. One ran fine for a day and then started behaving badly. The other was wonky from the getgo. Both had the threads worn off. It must've been vibrating like a tuning fork and destroyed the needles' threads, maybe the spraybar's threads too. Replacing both needles seems to have helped a lot. I haven't run them since we flew them last month though, but they worked great that day.

Put a short needle in it and seal it with the fuel tube, compressed with a #2 washer on top. I've occasionally had to stack a 2 and a 3 to keep the tube in place. See if it wakes up. This is getting frustrating, I know. Hang in there, we'll get it.
Rusty

[NEW222]

Ok. So, I just got back in now. Came home, yard work and the such. I had a long day, but I wanted to spend a few minutes with this monster I just received. So, I am not all that familiar with the compression stuff yet, but that is where I started. I removed the TD head and installed a standard head from another engine and a couple of the hand-made head gaskets with it. I then used the same syringe set-up as yesterday. Only change was using the Sidewinder fuel. I just wanted to give it a try, so I used it stock, 20% nitro, 10% oil [50/50 synthetic/castor]. I filled the syringe turned the needle to 3 1/2 turns, a couple flips of the prop with the spring, then hooked up the battery. It ran the syringe dry. Filled it again, fired right up, ran the syringe dry. Did this a few times and it ran decent, and did not stall out or quit on its own except for running out of fuel. So tomorrow when I get home, I will hook up the balloon, mix my fuel with castor to get 20% overall oil, will be 5% synthetic/15% castor, and run it again. I may also try removing the homemade gaskets and run it with just one gasket and standard head. Anyways, to me, it would appear that the engine was over-compressed as was suggested a couple posts above. I will look for a couple gaskets and then try the TD head again. But for now, it breathes! Before installing it on the plane, I will get a small washer and install the tube as per RknRusty's suggestion.

Thanks to all for the help given to getting this thing running.

[pkrankow]

Glad you are getting somewhere!

Phil

[RknRusty]

Good work! Glad to hear you've got it running.
I think the 50/50 oil is a fine mix. I've never had an engine varnish with that blend. Now you can go back and experiment with compression settings and really get to know your new baby.
Rusty

[getback]

Good Fun New222 Nothing like the smell of nitro success Eric

[NEW222]

Ok.  So I ran it today again on the bench just to make sure all is good.  It ran very well, once I got it started, again.  This time the only difference is the balloon tank that I used that will be its supply on the plane.  It is NOT under pressure, but still flooded the engine before starting.  So, once I got this figured out, it started and ran very well.  So I then went back and tried the TD head that was provided with the engine, and I was back at square one and no starting.  So I swapped the standard head back on yet again and tried it just to make sure.  She is a good starter and runner.  So I then removed it from the bench, cleaned it off then installed it on its new home again.  This time it will remain attached there permanently, or until the model tells me so....  I now know how finicky these balloon tanks can be and have learned a lot on this engine.  Also I have been learning about the TD high compression heads as well.  So thanks again for all of your patience and help.

[RknRusty]

Looks good. Is it all finished and fuel proofed?
Rusty

[NEW222]

Looks good. Is it all finished and fuel proofed?
Rusty

Thanks. It has 2 coats of clear Sig fuel-proof dope on it, and the nose(firewall front and back) epoxied for a bit extra fuel proofing. Wing is Doculam covering. Just need to whip up a set of lines and up she will go.

[getback]

I think you have a BAD head but that is just me (it should work) The plane looks GREAT and you should go fly that puppy with what will work for now getback

[NEW222]

I think you have a BAD head but that is just me (it should work) The plane looks GREAT and you should go fly that puppy with what will work for now getback

Could you please tell me what you mean by BAD head? I am under the impression that either they work or they don't. Thank you.

[pkrankow]

If it does not glow strongly it is bad, sometimes they glow weakly and run fine though. Sometimes the element is contaminated or the plating is gone (they are not solid platinum)

There might be other reasons, like the head was faced for added compression, so 5+ gaskets would be needed, which is odd. If there is no band or step between the trumpet dome in the head and the sealing surface then it has been faced down for added compression.

There might be a leak. This would mean that fine sandpaper, wet and dry type, with a drop of oil on a plate of glass can be used to lap the head down being careful to not wear one side more than the rest.

Phil

[NEW222]

Ok, thank you. I see that I still have a lot to learn, and this is part of the hobby.

[getback]

Thanks Phil , New222 , I have learned also on here when you see someone is having a problem with an engine or maybe something else it will usually turn into a discussion of difft. facts of what has happen to other members and you can get some good info that will be beneficial later on , or could bee a good BS session . I probably have more time on my hands that I need but that's the way the ball bounces . Here is a link to a disc. about glow heads https://www.coxengineforum.com/t8580-glow-plugs?highlight=glow+heads If you search the forum there is alto more . getback

[NEW222]

Resurrection of an old thread of mine. But I was doing a bit of reading the other night and had an epiphany I believe. So back to square one again. I had a difficult time getting this thing running earlier on, then got it running good in my eyes, good enough for flying. So, anyways, after reading a bit online, someone else was having problems with a Sure Start engine and mounting it. A bunch of people recommended taking the choke tube off of the engine and it would make for easier mounting of the 'Horseshoe' backplate. Then right after that there was a recommendation of cutting a couple of small notches or trimming back of the crimped venturi entrance on the backside of the backplate for air. This got me thinking. If I had this mounted firmly against my test stand and firewall where it currently resides, would I have running issues if it was struggling to get some air? So, I went and took a peek. It is indeed sitting tight against the firewall as it sits now. I then looked at my Babe Bee and it has a relief cutout on the bottom backside of the backplate, presumably for air intake. Would there be any problem if I shimmed this engine out with a spacer on each side made of 1/16" plywood. I am now firmly believing I may have inadvertently found my problem. Please share your thoughts and opinions on this if you like. I am interested. Thank you.

[706jim]

1/16" ply would be probably all you need to give the engine some air. The Babe Bee and Pee Wee engines have an air channel and its not really very deep.

[RknRusty]

...I am now firmly believing I may have inadvertently found my problem. Please share your thoughts and opinions on this if you like. I am interested. Thank you.

Not inadvertently at all, you found the problem with keen observation, and intuitively applied knowledge that you've acquired along the way. I too have inadvertently choked off an engine the same way on a test stand... a 2x4 pine block. I bored an air-hole through it when I realized my doofusness.
Rusty

[gcb]

...I am now firmly believing I may have inadvertently found my problem. Please share your thoughts and opinions on this if you like. I am interested. Thank you.

Not inadvertently at all, you found the problem with keen observation, and intuitively applied knowledge that you've acquired along the way. I too have inadvertently choked off an engine the same way on a test stand... a 2x4 pine block. I bored an air-hole through it when I realized my doofusness.
Rusty

Of course you guys are the only two who ever did that!

George

[RknRusty]

...I am now firmly believing I may have inadvertently found my problem. Please share your thoughts and opinions on this if you like. I am interested. Thank you.

Not inadvertently at all, you found the problem with keen observation, and intuitively applied knowledge that you've acquired along the way. I too have inadvertently choked off an engine the same way on a test stand... a 2x4 pine block. I bored an air-hole through it when I realized my doofusness.
Rusty

Of course you guys are the only two who ever did that!      

George

Whew, thanks George, now I feel better about myself.

[pkrankow]

...I am now firmly believing I may have inadvertently found my problem. Please share your thoughts and opinions on this if you like. I am interested. Thank you.

Not inadvertently at all, you found the problem with keen observation, and intuitively applied knowledge that you've acquired along the way. I too have inadvertently choked off an engine the same way on a test stand... a 2x4 pine block. I bored an air-hole through it when I realized my doofusness.
Rusty

Of course you guys are the only two who ever did that!      

George

Whew, thanks George, now I feel better about myself.

For extra points a rubber band can really make that back plate airtight to the bulkhead. Careful with those Goldberg style trainer mounts.

Phil

[Sponsored content]