Hey, Gil. How much runtime does your B40 have? Mine started running easily after about 40 minutes on the test stand, so I put it in a Cardinal. a couple of months later, after about 3 flights one day, I had to turn the needle in almost 2 full turns to regain takeoff rpm. Following that, runtime went from 4:45 to 6:00 in one flight, and I didn't have to touch the needle again for almost 5 months!

Apparently, the engine did the final bit of breakin during that 3rd flight that day. But this was following an additional 3 hours of runtime in the air. Perhaps your B40 isn't quite run in yet ? ? ?

 

  I'm not gettin very good gas milage on my Brodak 40, runnin 5% nitro, 22% oil, 1/2 castor 1/2 syn T/bolt idle bar plug and a 10x5 apc prop at 9500 rpm and about 5 1/2 min run time added a .014 head shim, no help, this mornin added another .010 shim will try that later today..
  Any suggestions    Thanks, Gil

Hey Gil:
How much fuel is it using for the 5.5 min run time.  I get the pattern in no sweat on my B40/ARF Nobler.  Engine is stock.  It has a 4oz plastic tank, using 10% Sig Champion.

  Guy's I thank all ya'll for your answers, Ralph I have about 2-2 1/2 hrs on the engine, and I'm usin a 4 oz clunk tank on an ARF Nobler that was "nekked" when I got it so I doped it and it tips the scales at 42 oz, I am gonna try the prop's that ya'll recommend ...   Again thanks for the answers...

Hi Guys,
I just did a test flight on a new(broke in by the instructions) B-40 using an APC 10/4 and the early small outlet muffler,10/22 fuel and the .305 venturi.The launch RPM was about 10,900/11,100. What a difference this made!! The 48 oz. ARF G. Nobler pulled like a horse and used only about 4 oz. of fuel.It was very windy & turbulent,so I didn't do many tricks.The lap times were about 4.5 seconds,so I'm going to try some longer lines next weekend and see what happens.This engine will cycle back and forth between a 4 cycle and 2 cycle like a pipe motor.You will never hear a B-40 sound like this.It runs in a dead 4 stroke and breaks quickly into a 2 stroke when loaded and back to a 4 stroke very quickly.
I got the idea from a fellow at VSC who flew a 52 oz. Tempest like this using about 11,200 launch RPM.Very impressive!!

Hi Guys,
I just did a test flight on a new(broke in by the instructions) B-40 using an APC 10/4 and the early small outlet muffler,10/22 fuel and the .305 venturi.The launch RPM was about 10,900/11,100. What a difference this made!! The 48 oz. ARF G. Nobler pulled like a horse and used only about 4 oz. of fuel.It was very windy & turbulent,so I didn't do many tricks.The lap times were about 4.5 seconds,so I'm going to try some longer lines next weekend and see what happens.This engine will cycle back and forth between a 4 cycle and 2 cycle like a pipe motor.You will never hear a B-40 sound like this.It runs in a dead 4 stroke and breaks quickly into a 2 stroke when loaded and back to a 4 stroke very quickly.
I got the idea from a fellow at VSC who flew a 52 oz. Tempest like this using about 11,200 launch RPM.Very impressive!!

That fellow at VSC was Jeff Welliver. Interesting approach to a setup, I must say. I recall that Jeff used the small outlet muffler (early issue), and seemed to think it was an important part of the package. My applause for following the setup so thoroughly, Rod. I could even provide an entire early Brodak .40 with small outlet muffler, all NIB, for anybody interested.  Contact me if interested!  Steve

Remember, a lot of old RC engines used an exhaust restrictor as a throttle. I have a Norvel 061 in a little "bounce-able" heli (LiteMachines), and it uses an adjustable exhaust restrictor for a quite effective throttle. I think Cox had something similar too.

HI All, Back i 2006 I learned that for my B-40's a home made restricter to .270" was just right for my runs and power for my ARF Nobler! Since then this same restriction continues to work quite well for me and my planes! I used telescoping pieces of brass tubing to reach this dimension.

Best of settings to all!

Phil Spillman

My Brodak B-40 is going into it's third airplane.  It is box stock except for the Adimisin Tongue Muffler I got from Brodak.  The Muffler is permanently attached now after the demise of the Olympic.  I run 4.25 ounces of fuel to get thru the pattern with about 10 extra laps when the needle is set right.  I run 10% nitro fuel,  Sig,  Power Master and Excaliber brands.  I have seen very little difference in the fuel.  The prop is Top Flite Power Point 10-4.  Don't know rpm, but, try for 5 to 5.2 second laps.  I also fly on .015 cable 60 foot center of plane to center of handle.

But, it takes a lot longer to break in the B-40 than the instructions say.  Have fun,  DOC Holliday

Hey, Gil. How much runtime does your B40 have? Mine started running easily after about 40 minutes on the test stand, so I put it in a Cardinal. a couple of months later, after about 3 flights one day, I had to turn the needle in almost 2 full turns to regain takeoff rpm. Following that, runtime went from 4:45 to 6:00 in one flight, and I didn't have to touch the needle again for almost 5 months!

Apparently, the engine did the final bit of breakin during that 3rd flight that day. But this was following an additional 3 hours of runtime in the air. Perhaps your B40 isn't quite run in yet ? ? ?

 

Listen to the League City man. Here is the typical drill on getting a Brodak 40 right:

30 minutes or so bench time. Followed by lots of air time, adding shims, removing shims, changing mufflers, changing venturis, changing fuel, fiddle, fiddle, run, run. Pretty soon you will find the magic combination that works, so you tell all your friends you found the "answer".

Now, put everything back stock, and it will run even better. The cure for all B-40 ills is to run it some more! (This answer is pure prejudice, but it worked once for me, and once for Ralph)

Larry Fulwider

 My mistake........

There have been many subtel changes to this engine since its introduction! One of the most important has been the newer mufflers which have come through with much larger outlet holes than the initial ones. This may appear trivial but it is most significant as it allows the engine to breathe much easier! Take a look at the size of you muffler's outlet. The newer ones are about .367" in id. That's slightly less than 3/8".

As to preferred props, my B .40's like the newer 11 X 4 Pro Zingers and the 11 X 4 MAS. Of course balancing is highly suggested!

Phil Spillman