I have a Brodak 40 that was broken in on the bench per Brodak's instructions and ran great. They state break in w/o muffler.  I now have it mounted on a Sig Force, powermaster 10/22, zinger 11x4, plastic tank set up on uniflow, stock muffler. (Have not flown yet do to following problem)

 No problem starting, runs rich and then runs away, cannot meter with needle. May take three turns to richen back up and then quits.  As the needle is richened....counterclockwise....it seems to lean and then richen and quit.

 Reset needle, will hot start with no problem but as soon as you pinch the line or point nose up it runs away.

 Tank height about 1/8 above venturi and  I have lowered.  I have changed to a metal uniflow,  a metal standard vent, replaced nva with a kustom kraftsmanship nva, changed plugs from fox std, k&b 1L, os #3 and 8, fireball hot.

Tank has 1/4 foam backing and I have not noticed any foaming in lines. Changed to a Big Art Tongue muffler, fuel line has been replaced, prop is balanced.

The fuel runs great in a reworked OS 40 FP that I am flying in an original TF Tutor , running uniflow tank...... It runs a 4-2-4 break and never misses through the complete tank.......

All of these changes and same result. 

What am I missing with the Brodak set up?  Help!

Alan

I checked the bolts, will put back on stand as soon as it is returned...loaned to friend......have not checked shims.

Thanks!

Alan

Sorry Jim........yes it is a Sig Primary Force ARF.  I will give the Pro Zinger a try next.  I did notice some vibration but did not think it would cause that much of a problem.  I have built and flown off and on for the past 40 years and this is my first ARF and it has me scratching my head.

Thanks   

Alan

Couldn't agree more about profiles generally - The few hours you save by not building a simple box fuse is generally lost by 3 to 1 or better in fighting with the profile nose to get a motor run.  So clean the filters, both on your fuel jug and plane, pull the needle apart and get the smallest bits of stuff out, and run it on the ground.  If you get runaway, have helper hold the plane while you reach in and hold the tank firmly.  If the problem is  fuel foaming, it will be obvious at once.  Or try a separate tank hand held, off the airplane.  Tom H.

Alan, one more thought:  the early Brodak 40's had mufflers that were a little too restrictive.  We've added additional exhaust holes at the rear of the muffler for better runs. 

I trust that you've checked the usual suspect - dirt in the tank/fuel line/needle valve?

I had a sort of similar problem recently, that was brought about by the venturi being too large/needle valve being too narrow/air leakage around needle valve. Fitting a wider diameter needle valve appears to have sorted that particular problem out, at least now the motor needles positively.