[8D] I have a bit of a problem with one of my older 1/2 A engines and I need some advice. I believe its a black widow type, .049 with a bypassed "attached to rear of motor", metal fuel tank. You know the little bowl shaped kind. Anyway, I was flying with it the other day and my engine performance became more and more erratic. I tried twisting the fuel tubing which surrounds the needle valve and which acts as a "sealer/extension". I noticed it ran erraticly but when I squeezed the tubing with pliers to adjust, it amped up and ran fine!! Ok I'm thinking needle valve air leak now! So I decided to remove the tubing from the end of the needle valve to see how it ran then. So I pull on the tubing, and out comes the needle valve, AND THE SLEEVE IT SCREWS INTO!!! What the!! So, I guess I found the air leak huh! First question is, how do I reinstall the thing? It has a little hole "port" in the side, which way should this point when I put it back in. Second, should I JB- Weld this thing back in or something? What do I use to keep it from popping out again? Any bright ideas will be much appreciated, cause I've never dealt with this issue before. Good thing it didn't fall out in mid flight, I'd never have found it!!

TIA ZZ.

ZZ, there might be some debate as to how you should secure the needle valve assy. back in. One thing is for sure, the parts have to be meticulously cleaned. Soaking in a jar of solvent that is taped to a orbital sander will sonic clean everything, or you can use a denture cleaner. Locktite has a formula for this application [permanent]. The little orifice should face the reed. I like to take it a step further and make an upper NV support that packs the NV seal tightly, so the needle is hard to turn. You will get very consistent runs this way.

an ya send me a pic of the motor? Sounds like you might be better off replacing the entire backplate! Send me a photo and I might have the backplate assembly you need! If i do I'll get your address and send it to you.
Till Later!!
RobinB!!

Metal tank, metal backplate? Mine looks to be knurled like a press-in deal. Press it back in till there's about 1/64 sticking out. A tiny bit of locktite should help.

[8D]Cool,

Thanks for the helpfull replies guys. I'll try to take a few shots of the components and get them posted here so I can refine my final solution. Seeing the bits might help you all.

ZZ.

WOW! I've never heard of one of those coming out before!

If a repair is going to be successful I suspect it'll need the Loctite or similar to bond the sleeve into place. The little hole in the side of that sleeve should probably line up with the hole in the backplates fuel line nipple. A bit of small sized music wire as a test probe to ensure alignment is probably a good idea. Be sure if you use Loctite or epoxy or whatever sealant that you use just a small smear and avoid it getting into the hole or into the needle valve area.

And ditto on the super clean prep first.

CP, I love your ghetto part cleaner idea...... LOL

BRUCE, again, as usual, I can't take any credit, the GHETTO GUNK BLASTER was one of those model magazine "idea page" contributions that I saw years ago. I've had one or two of these parts rattle out on me, and all I did was push it back in and cuss at it to stay put[>:]!

BTW, years ago I was taught by the local 1/2A GURUS to take all NIB COX engines, dismantle them and then sonic clean them over night. Amazing how much glittery, sparkly dust you find in the bottom of the jar.

Whoa!! combattpig, shoving and cussing is one of MY first "go to's" in just about any repair job. Your a man after my own heart. I have to aplogize to you all for the truly crummy picture I'm about to post of the engine (larger blur) and the needle valve and sleeve (smaller longish blur). My digi cam is down right now and I had to use my brothers. Its resolution doesn't allow for really close shots and when something is this size, thats pretty much EVERY SHOT!!! If you can believe it, the one shown is the LEAST blurry of them all. Might give an idea of what type engine this is though. So as it stands my steps will be:

1 Clean all parts

2 Line up port in sleeve with reed valve, ie front of engine

3 Insert (FLUSH with surface?!) and glue with some sort of adhesive.

The sleeve has little vertical ridges, (I assume to grab the walls) and I guess I should smear whatever adhesive I use into these before pressing in.

Let me know wht you guys think.

Thanks ZZ

That's about it, ZZ. Make sure you scribe some kind of index mark, so you can line up the hole in the side of the NVA with the fuel inlet nipple, not the reed. If the NVA is real loose in there, then it is probably trash, because you'll have a hard time sealing off the lower end, without accidentally gumming something up. At any rate, you don't have much to lose by trying.

Ok dude!!
Try it and if it don't work I happen to have a couple of extra tanks and backplates. If it don't work send me your addy and I can send you one!
Later!
RobinB!!

Thanks Robin! I'll keep you posted as to whether it goes well, and whether I need the part you've got. Thanks for your most generous offer. It seems to me that this thing is kinda tight going back in. Maybe when the engine is warm the hole expands a bit (hence the falling out situation) but now it seems it will be quite a tight fit. Combattpigg, you said line up the port in the NVA with the fuel INTAKE. Meaning the little round screened hole on the backplate of the motor, not the front (ie prop shaft end) right? Just wanted to be sure before its glued in!!!!!! Also, if this thing is hard to press back in, should I remove the needle valve itself when pressing this thing in place? And how much pressure should I apply before thinking something might be wrong? I'm contemplating pressing down on its top with a wooden dowel, and if it resists too much, tapping the dowel with a small hammer. Is that too abusive for this tiny part? Also, should it seat flush or have a bit sticking up? I never really knew what it originally looked like, And I assume it needs to be fully seated to work properly. Yet, if its supposed to seat "PROUD" ie with a bit sticking up from being totally flush, I don't want to keep bashing at it trying to seat it, if you know what I mean!

Thanks to you all! I'm buying some locktite today!

ZZ.

ZZ, I would use a tooth brush handle, or a piece of any hard metal to push it in. Wood could splinter and get inside. If it is too difficult to push all the way home with finger pressure, then I would pass the job onto a vise with smooth jaws. The back plate has a fuel inlet nipple cast into it, doesn't it? This is where the plastic fuel pick up line goes. If the little hole in the side of the NVA isn't lined up with this passage way, fuel won't be able to transfer into the NVA, flow past the tapered needle and finally dump into the air intake. Once you get those splines lined up, you are commited. I would not press it in with the NV in place.

[8D]Thanks CP. The deed is done. I saw what you meant after I removed the backplate. When I installed it I shined a bright light in the upper end of the assembly to be sure I could see light down through the port and aligned nipple, and it woked perfectly. I tapped it into place with a small hammer, and a soft flat wooden ruler as a"ding buffer". Looked to work perfectly. Thanks to all of you who posted here with helpfull remarks and hints. You all ROCK!
Anyway, during the process I found a BIG metal flake down in the sleeve cylinder shaft, it was almost clogging the entire port that the needle valve pokes through. Good thing I took you guys' recommendations and cleaned it all out well. I took a sewing pin a *****ed the little bugger out. MAN LOCKTITE IS EXPENSIVE!!!! $14.00 for a tube, from which I needed like two drops!! It cost more than the entire engine!! You gotta love 1/2A!!! Hmmmm, tube of locktite or two surestarts....tough call.LOL Well, you gotta do what you gotta do. By the way, anybody know how long it takes this stuff to cure completely before usage? I'll give you guys the final results of the operation once I get this thing stuck back in the AC and crank it up. Fingers crossed.

Regards ZZ

ZZ, I'm glad it has worked out so far, but $14 for LT? I would never send anyone over to that WALLPUKE store, but they might have LT for much less than where you got it. The stuff is hard to beat though, and you only used 5 cents worth.

[8D]Status report. Success. and thanks to all of those here who posted and made it possible. The little bugger fired up and ran just fine, so the repair was a success. I still however have some issue with getting the motor set at its highest rev-rate. This is the deal: It runs at a lower pitch than I know it can produce, not four stroking, but still not at the "scream" we all know is right when we hear it. The odd thing is, after re-assembling the little guy, I fired it up. Set the needle at its best position,(this unfortunately is the lower pitch range) then try to tweak the needle to amp it up, yet sometimes when I squeeze the needle valve with pliers to lightly turn it, the motor revs up into this higher range for a moment, then drops back down. Bizzarre!!!! I'm still thinking air leak of some kind. I know this engine can run in this range, but if I set it richer, it four strokes and dies, and if I go leaner, it dies as well. I'm stumped. But it seems the only way to get this thing to run full out is to stand ther and keep squeezing the needle valve!! Any ideas? TIA guys.


ZZ.

ZZ,

You may have trouble with the spring biting into the needle valve and case causing spring tension when you adjust. As soon as you let go, the spring will back the needle out a little. This can easily be checked by making a mark on the needle adjustment knob (if there's not already one there). Make your adjustment and see if it moves when you let go.

Good luck.

George

Hey ZZ,
Sounds a little like what my peewee 020 was doing- and it sounds like it might be a bit of gunk on the needle valve seat. With my peewee 020 I took out the needle and used a tooth pick to clean the needle valve hole/jet/seat.

J.M

Good suggestions guys, and more tinkering to come. I did some cleaning/inspection as per your suggestions, and seem to have the bug worked out. I got a good relatively steady flight out of it yesterday, so if it keeps performing without any hiccups, for the next few test flights, i'm willing to say we've got it beaten!

ZZ.