I have a brand new Brodak .25 that I'm trying to break in on my bench. I'm using 10 percent nitro fuel with 22 percent oil content. The prop is a 9/4 APC.The problem I'm having is that the engine would rather run backwards than forewords. Could some of you engine experts help me out?  I don't have enough experience to figure it out on my own.  Thanks very much,  Blaine

 i find that by bringing the fuel up to the needle and giving it an exhaust prime ,it is a lot less likely to case flood

I've only owned one of these engines so take this with a grain of sand. I've been successfully dealing with AAC ever since they first came out on racing engines so I know the idiosyncrasies of the technology. The B25 I had was poorly fitted from the start and got only slightly better with run time then, after several flying days, became so bad it would flame out for no reason other than a lack of compression. Pistons from that part of the world have a higher silicon content and must be fitted tighter. I looked into buying another piston/sleeve assembly and I see the vendor was selling pistons and sleeves separately which seems suspect. At any rate check for a healthy pinch at top dead center. I've had better luck and more power with the OS LA25.


MM

Thank you Mr. Buck. I would like to use this engine in a ARF  Nobler if I could get the airplane light enought..I'm 71 years old but never learned the entire stunt pattern. I figured the Brodak .25 is probably as strong as the fox .35 that I used in a green box Nobler in the early 60. I would very much to learn the pattern before my time runs out. 

   MR!  Finally, someone give the respect I am not due!

    I don't have any personal experience with the Brodak 25, and have only seen a few of them, so I don't know whether that is a good idea or not. What little I have suggests that it might be asking a lot of the engine. I know the approach will work with the 25FP and the 25LA (having seen multiple examples of the former, and with knowledge that the 25LA is even better, at least in the RPM range we are going to use). The difference is that the 25FP and LA will easily spin fast enough to fly with a 10-4 or similar. Most people I have discussed it with (like several threads here) talk about 9-5s and 9-6s on the Brodak. That suggests substantially less power in the air.  I would suggest going ahead (barring any contrary information from anyone else that knows more about it), but make sure you can put a 25LA in it if necessary.

      I have also heard a few stories and seen a bit of evidence of cases like Motorman's, where there is some manufacturing defect.  Of course, if everything works, it's not particularly notable, but failures or problems are. So problems tend to get over-reported. Brodak has outstanding customer service so if there is some QA problem I am sure that it will get taken care of.

    That's the best advice I have, but I hope some Brodak 25 owners can add to or correct it, if necessary.

     Brett

  I had a Brodak .25 in a Ringmaster that I bought complete from a local guy. Airplane and engine were almost new, the engine broken in per instructions. When I went to fly the airplane, the engine didn't have enough power to pull your hat off your head. It would seem to run fine. It would hold a needle anywhere I put it. I tried all the props I could lay my hands on. It ran like, as I usually describe this symptom, like it had a potato in it's tail pipe! A switch to an LA.25 saved the day.
   I have told this story here on the forum several times, and got an email from Tom Hampshire, who asked me to send him the engine. He sent it back with a modified muffler that had a straight out the back "stinger" and a larger diameter. I put the engine back on the airplane, and what a difference! I was much more acceptable, but it still didn't quite match up to the LA.25 in my opinion. The exhaust is just too restrictive. I tried the modified exhaust on the Brodak .40 I have in a modified Twister and man what a big difference in the 4-2 break it made on that airplane! Way too much break, almost uncontrollable. Switching back to the stock exhaust made it nice and docile, but still plenty of power.    Funny thing that Motorman mentioned the flame out issue. The last time I flew the airplane with that engine, that is exactly what happened to me, and at the wrong time! Crashed the airplane, but it was repairable. I thought it might be the tank I had just put on it, but I changed engines anyway, and the LA.25 runs fine on the new tank. The B-.25 looks fine at close inspection. It isn't hardly showing any blow by. I know guys down under in OZ like them for some club racing that they do, and maybe it is best suited for that. I have another one new in box and will have to try them on another airplane sometime, or maybe swap them to someone for OS .25's or something.
   As far as for your ARF Nobler, I would think an LA.25  will turn the trick, but try to keep weight below 40 ounces. The model size is an important issue. Full fuselage, and lots of drag on the design. I have LA.25s on a Twister, and have flown them on my P-Force that weighs in the 42 to 43 ounce range, but they have less drag in my opinion, and are right on the edge of the power band. This is a short coming when flying in any appreciable wind, especially with a model like a Nobler. But for simple sport flying and learning the pattern in better conditions, it may fill the bill. If I ever get around to putting one of mine together, it will have a older OS.35s in it. I built a Nobler year ago with one in it and liked that a lot. The OS.35s are available out there, are user friendly and make plenty of power, you just need to run proper oil in it as it has an iron piston and liner in it like the Foxes and McCoys. I'm talking about 25% oil at least and 10% nitro. Under heavy use, the rods can become worn but I don't think you would be putting that much strain on it sport flying. I have had good luck running the FP.35 and .40 in the inverted mounting position stock out of the box with an extra head gasket, smaller venturi (like the FP.25), tube type muffler, and 10-4 to 11-4 pitch prop. The neat thing about the Nobler ARF is you can leave the cowling off while you are trimming the airplane, and it also makes it easier to change to a different engine. Make sure you epoxy in some gussets or braces on the motor mounts to stiffen them up to dampen vibration. Some guys cut them off, epoxy on another layer of 1/8" plywood, and use a plastic R/C mount. Use bolts and blind nuts to attach the R/C mount, and if you are careful with the mounting holes, you can have different engines attached to multiple engine mounts and it makes swapping out much easier, if you like to experiment.
 There is lots and lots of stuff here on the list, and over on the engine set up section on this specific subject. I'll bet the ARF has been flown with just about any engine combination you can think of by now.
   Good luck with it and have fun,
    Dan McEntee

Yep, Brodak 25s are nothing but trouble, please send me all you have, this applies to all who have them. My B-25s (about seven or eight of them) have all kinds of problems. Also, I'll be happy to trade an LA25 for any Brodak 25, (nib or used, it don't matta').  I've a few LA 25s. Also a TT25. And, a real bonus, you can keep your mufflers. No, really! No need to thank me, it's just the kind of guy I am. 

For an act of kindness of this magnitude, I would think it a given that shipping costs would be picked up by the lucky person unloading his recalcitrant B-25(s),
dg

In my case customer service was N/A since they had no parts to fix it. I intend to get the sleeve pinched by RayAracing and see how it goes. I guess if I had 7-8 of these engines chances are a few of them would run good. One thing I did that helped the power allot was to open up the venturi and muffler hole a small amount. I think the trick to this engine is to let it build heat but it needs to have a better piston fit to run hot or it will just expand the sleeve and lose compression. So there's a narrow window of getting it hot while maintaining piston seal.

MM

On the super slow rat racers we use about a .315" venturi.   On the pit stops we tip the airplane to dump excess fuel out of the venturi to prevent flooding the motor.   The first time I flew a brodak 25 on a ringmaster I thought my, that is a bit weeney.  The stock venturi is just a little small.  Nothing a drill can't fix.