Re: Pre-revlite Norvel/ Ame 049 problem

fredvon4 Sat Jul 06, 2013 1:44 pm

Not sure on the RC carbed versions how fast they will spin, but of my three (all non RC) the .049 AERO out of the box is a high RPM evil little bit of engine.
The .061s (one Big Mig and one AME porting) require a lot of tinkering with head shims, Nitro, Prop size and pitch, glow plug type (I have NV, Merlin, Cox, and Nelson plugs to experiment with.

Then there is the break in duration.... The .049 AERO hit consistent max RPM with about 8 oz of bench running and I expect won't get much better.

Both .061s are all showing no difference from 1st oz til the current 16oz total fuel run. Ken and others do note that some of these engines do not come to life until a LOT of high heat time is on the Cyl/ Piston set.

FWIIW I did not polish the cranks or lap in the piston skirts as some do... just running 25% Nitro and straight sig castor at 22% right now

Just my opinion here: Seems to me the NV (Norvel) engines below .074 were engineered for WOT high RPM control line use and I suspect the RC carb is an after thought to expand sales.

My observation of the RC version .061 a club member flies sounds like he mostly is at 3/4 to WOT for most of his flight and many times when he turns final for the approach to land and chops throttle it just dies. He is very good RC pilot, so he just floats it in like nothing is wrong.

He has another pylon plane that has the NV .074 RC and it runs and flies his same style flawlessly

Listening to the two engines pull his aircraft, the .061 always seems to bog or stutter as he adds throttle. The .074 sounds perfect in any attitude and throttle position, just like the other well tuned larger engines flying at our field.

tru168 Sat Jul 06, 2013 9:47 pm

I try to search the entire web in the past whole week, I found someone successfully flown a Big Mig Revlite 061 RC with satisfied result, but no successful story about AME 061 pre-revlite RC . I found several AME RC users facing the same problem as mine, they can't throttle well.
The AME perform really well only when its on full throttle, with constant high speed. (needle setting only 1 1/2 turn)

I've heard that earlier day in Russia , their RC engine designed to run on 0% fuel, I'm not quite sure that little AME can perform more stable if using FAI fuel, but I think it will run even worse with non- nitro fuel.

I called up my club mate yesterday, who just bought another Norvel 074, and he show me his 074 this morning, I compare the 074 with AME carefully, the carb. design looks pretty much the same , I can see a little air bleed hole on the AME carb, but no air breed on 074. AME using shorter brass needle, and 074 come with longer aluminum needle. I think its true that AME add throttled carb. just for marketing reason.

I will try to experiment with others glow head, prop, and fuel combination, as for back plate pressure cover, I'm not going to order from NV right now, I'm in Asia ,the shipping cost will be far more higher than the back plate cover. Its actually fun to experiment with AME, I learnt quite a lot IC knowledge from this little engine, and from you all. Thanks !

Ken Cook Sun Jul 07, 2013 7:05 am

I agree with your findings on the nitro.I couldn't achieve satisfactory runs on 10% fuel and the engine would just quit until I poured some vitamin N into it. I run mine with high nitro 40%-50%. I also found that too high of oil content causes the plug to cool. I won't get into what oil percentage I use but I can tell you I never wore a piston liner out but I have one engine now on it's second case. The engine runs better when it develops severe play in the crankshaft, that's until it starts wobbling under high rpm's and resonates. It becomes apparent that you need to replace the case then. Ken

tru168 Sun Jul 07, 2013 7:51 am

Hi Ken,

That's interesting to hear that the piston liner need a new case , then a case need new set of piston liner.
I've seen somewhere on web, mentioned that Big mig using bushing and AME came with ball bearing, don't know how true, I need to check mine to confirm that statement.

Ken Cook Sun Jul 07, 2013 8:42 am

None of these engines use a bearing or a bushed crankcase for that matter.The Norvel .15 Big Mig does use a bushing while the AME .15 is ball bearing but that's not the situation with the .049-.061's. It's just the crank riding directly on the aluminum. What I've discovered in my experience is that not just some, but almost all of them come with too tight of a fit. The Aero and also the AME's are all out combat engines. The cases are shorter and they're designed to run out of the box with very little break in time. What happens is that towards the front of the case, the crank begins to pickup aluminum on the shaft and it will gall the case. I have several new in the box versions and when I'm ready to take them out to begin running them, I have a friend of mine do a little work on the case. I've had some of my old cases bushed with bronze, but they never seemed to run like they did prior to replacing the bushing. I contribute that to many factors as I believe the one major factor is that the case now is thinner due to the area the bushing now accommodates.

The only known small mill engine that I know of that uses a bushed case is the AP Wasp .061. This is more than likely due to the choice of aluminum used in the casting wasn't suitable for bearing useage. My experience with the AP was not favorable and the bronze bushing wore out in less than 50 flights. The crank wobbling was causing such violent vibrations that it would just take out a glow plug everytime I ran it. I spent more money on plugs than I did on the engine rendering it a paper weight currently. I always wanted to revisit the AP Wasp. I was running the engine above it's claimed or stated rpm numbers. As a stunt engine it might of worked terrifically but in my search for a inexpensive combat engine, it did work at least for a short period of time. Ken

tru168 Sun Jul 07, 2013 8:52 am

Hi Ken,
Thanks for your info about the wrong bushing/bearing info that I've heard.
Its a shame that AP WASP can perform well, but with real short lifespan .
I just post another topics on Cox discussion, I might keep this small engine for others speedy plane, and choose Cox engine for the trainer. Most Cox engine can take heavier load than AME, I think. Cox reedie's sweet spot rev up at 14,000-17,000 rpm but AME seems need to be above 22,000 rpm.

andrew Sun Jul 07, 2013 9:24 am

tru168 wrote:I try to search the entire web in the past whole week, I found someone successfully flown a Big Mig Revlite 061 RC with satisfied result, but no successful story about AME 061 pre-revlite RC . I found several AME RC users facing the same problem as mine, they can't throttle well.
The AME perform really well only when its on full throttle, with constant high speed. (needle setting only 1 1/2 turn)

The timing and port design of the AME does not lend itself to good throttling. These engines are set up to run competitive events and to run wide open. I don't think you will ever have good mid or low range performance with yours. As is many times the case, once the NORVELs became readily available to the general public, there was a demand for a throttled version. The AME can be cantankerous and outside of the combat and speed community (folks who understood how to manage high performance engines) it was found to be difficult to run and to tune correctly. Keep in mind that the AME was a major step up from a COX .049. The Big Mig was developed to give the market a kinder and gentler engine that performed better than the COX, but had running characteristics similar to the engines most folks had been used to. It was not the horse the AME was, but was easier to tune, ran fairly well with a throttle and met the needs of the majority of users. If you only want to go fast, get an AME. If you want a sport flyer, the Big Mig is likely your best choice.

gcb Sun Jul 07, 2013 11:32 am

tru168 wrote: Read quite a lot about AME recently, Ame don't like big heavy prop.

MA 6 X 3 - 15,100 rpm
Cox 5 X 3 rubber duckie, - 17,400 rpm.
APC 6 X 2 - 19,600 rpm. (easier needling)

These are probably quotes for an .061. I believe you have an .049. YOU NEED SMALLER PROPS.

Yes, the AME is high performance and needs a good venturi (throttle/carb) velocity to pull fuel. Yes the AME is more suited for racing.

For your purposes a Big Mig .061 would better serve you. The favorite props for an RC Big Mig .061 are the APC 6x2 and the APC 5.7x3. I do not yet have any NV's but I do have pre-Revlite and Revlite NORVELs.

You may find that CL and RC prop recommendations are a little different because the USE is a little different. You may also find that recommendation are usually for .061's because there are a LOT more of them in use than the .049's. I have a NIB AME .049 (no, it's not for sale). The .061 has more power per displacement (and more raw power) plus the Big Mig has better handling so from what I understand the Big Mig .061 outsold all of the others.

You can still use your AME .049 on an RC trainer as long as you know and accept its running characteristics.

Oh, one more point...early on it was discovered that the NORVEL engines run a little cooler so impurities such as rubber from fueling devices were contaminating plugs, especially the ones used before the "Freedom" plug came out. Contaminates would coat the plug and prevent the catalytic action with alcohol giving the same symptoms you described...slow down or stop when the booster power is removed. There were recommended fuels and fuelers at the time. That problem went away with newer plugs.

Hope this helps a bit.

George

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