combatpigg

My Feedback: (3)

I have tried to get the 1cc NORVEL AME to give good performance and life expectancy, but always end up with a run away piston growth problem. I have adapted the COX/KK needle which improved things for running on bladder, and I top off every fresh gallon of fuel with 8 or 9 ounces of caster. I believe the problem is from piston swelling, is there away to heat treat the piston?

fastlash

My Feedback: (7)

So what running syptoms are you having, aan or revlite, and how much run'in time on the engine? are you using the 1.2 volt plug or the 1.5V, what percentage of nitro? how many head shims? check the back cover for leaks witch was a real headache on the early ones, 5.7x3 apc?? I only add about 4 oz. of castor to an 18% based fuel,is your tank on center with the fuel jet, my AME's were always very hard to get consistant runs, but they will run very hard when right, I would like to see the needle change over, the needle was always my biggest complaint with the AME under fuel pressure

combatpigg

My Feedback: (3)

FASTLASH! thanks for the reply. The running symptoms were as follows , send plane off slightly rich and on first down wind past the motor would unload into a perfect setting and run until the bladder was empty. The second run would usually be like the first, except I would experience over leanness towards the end of the run. Changing bladders didn't usually help. subsequent runs would just get worse and worse. You could inspect the liner and piston [AAN]magnified and see the beginnings of material transfer from the piston to the liner. The back plate was suspected and sealed off by wicking CA into the threads [ don't worry I have never seen the glue go any where it wasn't supposed to] I have run 15% or 30% nitro, I have run several different combos of fuel and compression, and I have owned 3 of these engines, not to mention that I fly CL combat with a half dozen or so guys with the same problem. The engine has potential but I think there are some basic metallurgical problems with the pistons' dimensional stability.. I don't know which glow plug I was using, I assume 1.2V. The prop was an APC 5.7*3 or a COX 5*3. My knowledge about this stuff you could put on the head of a pin, but I do know that aluminum alloys with very high silicon contents were developed to combat[there's that word again] this problem. Fox uses this stuff for their pistons. The first generation of these[AME type] engines were sold to combat guys[before NORVEL] and they didn"t have this problem

Jeff Leavitt

Hi Guy's

Interesting problem you have here combat dude. I'm having trouble with the idea that the piston swelling is the main fault here. If that were the problem, you wouldn't have gotten the first flawless run. I have noticed the galling on the pistons sometimes though, but usually when run very hard without sufficient break in time. Fastlash is right about the added castor. One oz. added to a quart of fuel will raise the oil content slightly over 3%. 20% castor oil is totally safe. Piston fit for these engines is a black art. Just a smidge to much lapping and you'll have a poor runner. Light machines has a needle they developed for their helicopter. Long sloping needle, about 80tpi as I recall, best needle for the AME's that I've found. I suggest you call Larry Driskill at Kitting It Together and get some of his combat props. You'll be smoking your buddies butts with them. And IMHO your over propped for combat. Be sure your head is sealing. Check it for compression leaks. Don't use that really small ID fuel tubing. I have really good luck with Aerotrend small. Make absoutley sure your needle is free of foreign matter. Strain your fuel through a coffee filter! This is sooo important. Your adaptation of the KK needle sounds interesting. How'd you d it? Rgds, Jeff.....

combatpigg

My Feedback: (3)

HI JEFF! The norvel needle housing can be pulled out with pliers, then match up a tap with the COX velocity stack threads. Tap the NORVEL case dry, then install the COX parts with a dab of JB weld on the threads, because if I remember right you don't get an ideal thread engagement but if you glue the threads it will work great. My problems were in a RC delta that needed the bigger props, and I was running a bladder feed, so fuel delivery was never to blame. The COX/KK set up helped with consistency. I would do the factory break in routine and run it on the bench till the squeekyness was gone at TDC. Pistons do grow, but in such a tiny bore it should be easy to control with fuel mixture and oil. 8 ounces of caster added to 128 ounces of brand X fuel gives that added security because you know are running at least as much caster and oil content as the mail order fuels. I have run those props that you are talking about and they are great, but I would rather still run cut down COX props[when I'm flying CL combat]. From what I gather , JEFF, you are having good success with your AMEs and is it mainly because you lap them first?

Jeff Leavitt

Combatpigg,

I have about six ame/Norvels that are all pretty good. maybe one or two are stronger than the rest. IMHO a ame that will turn a 4.7x3 28-29,000 is about as good as they get and still be reliable enough to race with. If the motors will get there and show no evidence of galling I leave them alone. If the skirt appears too tight, I chuck the piston head first in the lathe, and carefully dress the skirt i.e. 1/8" from the top with 2000 paper. (gives georgous finish) Run the engine again. Look at the piston with 10x glass. (you'll learn a lot if you look close) Still tight? dress it again, repeat till no evidence of galling. Be careful as you can't go back! It's amazing how much time you can get in one of these little motors, right A.J.? generally I race my VA's instead of the AME's they're 2,000 + stronger than the AME's. I've done several for friends and they are flown very successfully albeit not quite as strong as the VA's. Rgds, Jeff

combatpigg

My Feedback: (3)

Thanks JEFF! . That was real informative. You are right about what close inspections reveal.I'm encouraged now to try and bring a couple of mine back to life. Thanks again!