Was out at the field today with a friend, struggling to get a Babe Bee running long enough to make him dizzy (he's re-learning CL after a mere 42 year digression into RC).

The needle valve housing is loose.  Way loose.  Not only does it visibly rock around in its hole, but you can tug on it and see it pull out over than 1/32 of an inch (it's somewhere around 40 or 50 mils).

He was thinking to glue it with CA -- I was looking at the size of the gap and thinking JB Weld.  Is there a better way?

BTW: does anyone know the thread size on those things?  Are they some standard "super fine" thread, a die for which I might buy at McMaster-Carr, or are they a total Cox Custom?  I'm kinda thinking it may be fun to build a backplate from scratch, just to say I'd done it...

  Same here--I got a good BB backplate too.   The needle body on all the baby baas I have messed with are pressed into the backplate ---not screwed in.  That being the case,  Really cleaning the areas very clean then a light coat of JB Weld around the serrated top end  should do th job--- BUT  be sure the small fuel outlet hole in the spray bar is properly located or it might not draw fuel properly.

  Let us know how things work out.

  Bigiron

      You might try a couple of wraps of plumber's teflon thread tape.  Measure the turns from full in to get the running setting and go right to it when you put in the needle with tape on it.  Not a permanent fix, but it'll buy you a few afternoons of flying.  Tom Hampshire

You misunderstand.  The needle is not loose in the needle housing -- the needle housing is loose in the backplate.  On the last attempt I tugged up on the needle valve, the needle & housing pulled out of the backplate by about 40 mils, and the engine quit.  We gave up...

Tim, do you need a backplate?

That's a good question.  It's a friend's engine, but I'm not sure which friend.  Tex, a club member, is trying to get Jim, another club member, back into flying control line.  I'm helping and abetting this process as much as I possible can.  To further this, Tex gave Jim an engine and a kit of parts for an all-sheet trainer.

So, I think it's Jim's engine now, but maybe it's still Tex's.

At any rate, I'm sure that Jim, and probably Tex, would be grateful if a backplate in good condition crossed Jim's path.  I've got one or two lying around that I could share, but that would mean that I'm one backplate short of an engine for the rest of those bits.  I wouldn't want to deprive anyone of a backplate if they may need it down the road.

I just finished building "Babe the Monster Bee" for Jim -- he's got a single-bypass cylinder, and a 6x3 prop.  This one has a two-bypass cylinder, and a 5.5x2.5 prop.  It screams (I don't know how long it'll last -- I cut the reed from sheet brass).  I need to get it onto his plane and into the air before he realizes just how much difference there will be.

I should learn how to anodize -- then it could be "Babe the big blue Bee".