I had the same problem with my B40 last week, mine was bended also, I tried to straigthen up but didnt work , the problems is that air is getting in and gives the erratic run. I ended up installing an OS 40 FP spray bar and needle.
The venturi holes are a bit big for the spray bar but I fit it using an eyelet on each side, you have to cut the smaller lip of the eyelet and get the big lip flat and it fits perfect.
I flew it this morning and it runs pretty good, it started on the first flip, runs pretty good 2-4, you will have to open the needle 5 turns and to start and go from there.
 

Question,  Do I need to get a whole new assembly or just a needle valve itself?

Also,  would a Super Tiger 51 NVA fit?

 I do need to go over the system.  It was getting dark at the field when we were working through this. 

Today, I noticed three nuts - a larger one on the outside where the needle goes in.  How tight or far in does it need to be turned?

Also,  I have noticed in filling the tank that fuel squirts out the venturi before the tank gets full.

Do we need to pinch of the line to the engine while filling?    It is a regular non uni-flow tank. 

Thanks Geoff,

      I made a close inspection in the sun on a patio table. Great viewing.  We were working feverishly at the field as the sun was setting. I am sure that the NVA needs changed.  I will probably try the ST assembly.  However, a whole new assembly at Brodak is only $9.95 or so.  Thanks again.

I have another question.

Currently by mounting the motor with the head down,  the flow into the engine goes in on the inside wing side.  Would it be of value to mount it so that the fuel flow goes in from the outside. 

Another question.

When I fill this tank - it's a standard vented tank - the fuel runs out of the venturi before it runs out the bottom vent.  What does that mean?  It sure wastes fuel.     I have been pinching of the tube to the engine to prevent that.    Has anyone else ever had that experience or similar ones?

Thanks for all the advice and help.

You have something pluging the overflow or the needle is open too far.   

Today,  I installed the ST-51 needle valve.  It fit fine.  However, it has a much bigger hole.  What effect would that have?

I also found dirt in the fuel filter which I cleaned out.

I turned the valve around and the fuel is coming in to the engine from the outboard side.  The needle is very short. I had to use needle nose pliers to adjust it while running. 

I got one run - too fast leaned out and another one a bit too rich.  Neither time did it run the tank dry. It ran at the most - two minutes. 

 It is a normal vented tank.  I also had trouble keeping it running with the glow plug off. It would stop. That was with a Fox Long.  Then I changed to a shorter plug and it stayed running. 

I'm still frustrated.  I'm using Powermaster 10/22  half and half.  It's almost gone.  I have some Fox 10/20 (all castor) and some Sig Champion 15/20 half and half.   I'm thinking of trying them.

Any suggestions.  This motor ran fine on the Powermaster and the Sig when it was side mounted in a profile Cosmic Wind.

'What is the effect of having a bigger hole in the spray bar than than the original?'

So long as you can actually stop the fuel flow by screwing the needle all the way onto the seat, very little. The usual internal layout is that the taper on the needle seats on a step or shoulder inside the spraybar. As you open the needle, the fuel flows around the taper and along to the hole. A bigger hole may mean slightly less fuel atomisation but I would be surprised if the difference, if there is one, is noticeable.

As for your previous question about the location of the hole, just out of sight and facing back towards the cylinder is the way I always do it. Facing forward should not make a difference. Just out of sight as you look down the venturi will give maximum suction.

Cheers, Geoff

       Allen, I had similar proplems using the Fox plugs. I just had to replace them more often. Once I noticed the rpm's falling off when the plug was disconnected I'd get rid of it. In terms of fuel I'm using Powermaster 5%-22% oil. I use Sig r/c long plugs now and haven't replaced the plug in over 2 years now of consecutive flying. My engine runs terrific. I use a APC 10-5 prop. I would just make sure you use a good quality hot plug. I truly don't see the need for you to up your nitro if it isn't necessary. Ken

The best plug I've found, so far(I haven't used Thunderbolts, etc.), for overally use, is the OS #6 (old A3).  It is a hot plug, and maybe that seems to work best for me, both in CL and "dark side" flying.  A problem I've had with the Fox RC Long is that, especially on a profile, using a "hang on" lighter, the electrode will loosen up and cause a compression leak and weak burn.  Just my opinion.

Glen Wearden