SharpProp

My first plane a few years ago was an AT - 6 Texan kit with a Big Mig .061 engine. I started building it and I almost completed it ( up to just about the covering stage of the build. I stopped because I got frustrated when I couldn't get the .061 to fire up. I was green and didn't know much about the hobby and tuning engines and such. I have a few questions about the engine because I am concerned that I may have ruined it. When i first started working with the engine I couldn't get the motor to turn at all. It was frozen up horribly. My dad suggested that maybe it wasn't machined properly so used some kind of sand paper and carefully used it on the inside of the cylinder and finally freed it up enough that I could do the 100 turns and finally it loosened up. I never got the engine to fire by flipping it with my finger.
Well the other day I got the plane out and decided that after learning to fly and tinkering with engines on some normal trainers, I would finish this plane and get it going. I put the .061 on a make - shift test stand, added some 25% norvel fuel, used an electric starter......And SHE RAN! only for a few seconds. I didn't have time to tune her out or anything but tonight I will give it a shot and see if I can keep her going. OK so here are my concerns:
1: what are the odds I ruined the compression in this little guy? It has a little bit of compression but I don't have another 1/2 a engine to compare it to. it still sucks up gas ....and I did get it to run for a bit.
2: is there any kind of low end needle setting or is it all on one needle.
3: will the size of the fuel line make a difference? I'm using the standard stuff that I use on my .40 plus size engines.

Thanks for the input!!!! any other advice would be greatly appreciated!

Jburry

I'm afraid you've probably ruined that engine. The Norvels were very tight when new, and standard procedure for the tighter ones was to heat the cylinder head with a heat gun for the first few startups. The piston and cylinders were ceramic coated, this gave them the longevity and power they were known for.

I guess there's a chance that it's not dead, so some experimenting may be worthwhile. Newbies have very little luck hand propping 1/2a engines, they can be very frustrating. There is no low-end needle. Instead, the main needle tunes the entire RPM range, so it must be tweaked until a reliable idle is obtained. It needs a few tanks of fuel (2 oz each or so) run thru it first though, until they're broken in they will not hold a reliable idle. It should be fired up full throttle, and the mixture set somewhat rich, but by no means 4 stroking rich. Just let it burn thru a couple tanks.

Standard fuel line is fine.

Read the Norvel Engine Faq at the top of this forum for a whole lot of info on breaking in, running and tuning these little gems. I hope it's not dead, since they are no longer in production and the currently available replacements (mostly AP Wasp .061) aren't nearly of the same high quality.

They are much easier to run than most 1/2a engines, and actually have a decent functioning throttle. I'm happy if my idle rpm's are 1/3rd of WOT, so in my 21,000rpm (6x2) Big Mig, I'm pretty content with a 7000rpm idle. Slow enough to land.

Good luck,

J

SharpProp

I really hop I didn't mess up the engine. Any signs I can look for to tell if I have. Also does anybody know where I can get a new cylinder if I have?

Jburry

With a drop or 2 of oil (30wt or so) in the engine, turn it so the piston is at top dead centre. Do it reasonably quickly, and stop at tdc. 10 seconds or so later, push the prop over, and the cylinder should have retained the pressure (ie should not make a big sucking pop noise when the exhaust port is uncovered). This can be a bit tricky with the Revlites because they have so much "pinch" at TDC, ie the piston sorta seems to seize there...

If the engine's well lubed with light oil (after run, or 30wt) (the oil residue from the fuel can make them turn sluggishly by hand, feeling sorta stiff), and you hand prop the engine, it after compression the prop should oscillate back and forth a couple times making a sorta "budda-bump" sound.

If the cylinder pinch is still good, turning the engine slowly should result in the piston sorta hanging up at TDC, and needing to be pulled down slightly to free it again, if you follow my drift.

Read that Norvel thread at the top. Try to follow the breakin procedure they list. Try several times, if at first you fail. This is not quite the friendly beast the .40's your used to are, more finnicky and taking more patience and subtlty than you're used to. Adjust the needle 1 or 2 clicks at a time, releasing it each time. Just touching the needle will cause a drastic change in the engine's performance, so after each click in the direction you think you must go, let go and observe, then make the next tiny change.

If you get it running Ok at WOT, then begin to throttle it back, and evaluate wether the idle is rich or lean, go back to WOT, adjust 1 click in the direction you think is needed, then try the idle again. The 400rpm slow of peak rule does not apply here!

New cylinders and pistons aren't available anymore. The auction sites are a source, as are those who hoarded the engines when Norvel began to go away. Ask around your club, you may find someone who put one away after running outta patience. Once you get'em sorted (and it's worth the work!), you'll love'm

Here's my Big Mig powered 1/2a Herr Aquastar flying boat:

J

makoman1860

My Feedback: (1)

EEEEk,
I have the feeling you ruined the engine. Norvel used an aluminum oxide treatement on the cylinder, its only about .0015" thick. Unfortunately if you touched it with an abrasive you most likely wore through the oxide layer....and its kaput. New cylinders and pistons are like hens teeth, your better off buying a new engine I hate to say it. Even if you get this running, im guessing it wont for long.
sorry bud, if the parts need a good home ill give you a fair price as I have spare cylinder sets and can always use bottom ends.
-Aaron

Mr. Mugen

I just picked up 2 newin box big migs off the bay for 60 bucks a piece. just looked and there are some cylinders, pistons, etc available there now.

gcb

First, which version Big Mig .061 do you have. Early ones had metal colored fins and a venturi or carb that was epoxied in place. Later versions had black fins and the carb was bolted on.

The first ones were aluminum pistons in a chromed cylinder. The later ones had an aluminum piston and an aluminum oxide hard anodized cylinder.

The only way you can tell if you damaged the engine is to run it. Start it (preferably by hand) and run it for a few tanks of fuel to get used to it.

If it flys your plane, it's good. If it keeps gaining power for a few flights, it was not damaged.

Mishandling an engine can ruin it, but it can also just take away some of its useful life. It may well serve you well for a long time, even if you damaged it enough to be "over the hill". Also remember that an "over the hill" Big Mig may still produce more power than most other engines of its size.

Good luck with it.

George

old git

Hi J,

I bought an Aquastar kit a while back. It looked so good to me that I bought another kit without having built the first. Not long after there was a long exchange of posts about how the Aquastar would not take off without mods to the front end of the hull. Did yours work OK, did you have to modify the hull? My kits remain unbuilt.



old git - - - - aka John L.

makoman1860

My Feedback: (1)

Hey George,
Ive got 2 BigMigs, an early one with the "golden" color cylinder, and a later "grey" colored one. Both are actually aluminum oxide on mine. The only chrome version I saw had a brass cylinder. How many versions of these dang things are there??

longdan

Read the Norvel FAQ at the top of this forum. There's lots of good info in there.

gcb

The oldest I have is the AME Zeus. It has no muffler and has a large intake. I believe this was for CL Combat and should be run on pressure.

My next has metal (steel?) fins with a muffler that runs straight back. Mine are Big Migs (.049 and .061) from the time frame when NORVEL was switching to the "Freedom" plug.

The next version that I have of Big Migs (.049 and .061) have metal fins and mufflers with a rotatable side outlet. I also have an AME .049, same thing.

The final versions that I have of Big Migs (.049, .061, .074) are with anodized aluminum fins and a bolt-on intake.

All of mine before the anodized aluminum fins appear to be chromed (shiney) in the bore. The aluminum finned version has a gray bore, just a bit lighter than the outside.

Of course they made lots of changes so there are probably versions that I do not have.

AFAIK, the anodizing process (Revlite) is only used on the aluminum finned version. Hard anodizing actually combines the aluminum and aluminum oxide, it is not just a coating.

I THINK NORVEL introduced the Revlite process on the .15 AME and Big Mig. When they introduced the .25, it was Revlite.

George

ProBroJoe

FWIW, I just picked up a couple Norvel .061s off the infamous auction site. (Apparently they were also used in Bolink Legends RC cars.) Athough these have the big heatsink heads and throttle muffler, a lot of the other parts should exchange with the Big Migs. It's interesting to note, the cranks are threaded #5-40 like the Coxes....

Oh not bad for $24 NIP, huh? (I just looked and there's at least two still available - Item number: 160244220461)

injunnut1

Hey ProBroJoe,
Thanks a bunch for the great CLUE ..... I just ordered three of the available ten that were still left!

Thanks Again, Donald Garry

Mr. Mugen

Roger that! I took 2 also. Thanks. These are just like the heli versions from what I can tell.

VGE Hobbies

My Feedback: (9)

Yeah I picked up 4 of them and just got them in today. Pretty nice for $24 bucks. How do you remove the velocity stack on these engines?[:@] Other than the velocity stack and head looks just like the Big Mig .061.

Falco250

Are these engines supplied with a Norvel plug?
Falco250

ProBroJoe

Yes...

Everything you see in the picture is included (except the prop screw and washer).

Jburry

Hey there Old Git!

The Aquastar is a great flying little plane, and I have flown it off water. I don't like following directions to the letter so a number of things got changed in my build:

1) I added chine rails. There was an addendum to the manual about this, but my rails extend a bit further forward than they showed. Started an inch behind the nose, and ran to about 1/2" ahead of the step.

2) Build it with UP thrust, not Down thrust as it's shipped. I put about 3 degrees upthrust in. Downthrust is inappropriate for high engined planes. Up thrust also puts the elevator into the prop's slipstream, making rotation possible.

3) Bolt on wing.... Elastic bands make it too hard to adequately seal the airplane watertight.

4) Ailerons and less dihedral - More fun flying. Halved the dihedral.

5) Moved the tip floats in one rib bay. Had to improvise a mounting method since the ailerons are now in the way...

6) Moved the tail pushrods to the top of the fuse. Aquastars float LOW in the water, pushrods under the stab were a bad idea.

7) Built in the fuel tank. Hated the look of the engine pylon as per the kit, so I cut the pylon former to fit the 2oz sulli slant tank inside, and planked around it, with an access hatch.

I was flying it last week at the field, hand launch. Really nice flying plane. We have a float fly in Mactaquac this coming weekend, I'll go to ensure 1/2a representation.

I've only flown off water once yet. Faced with 3-4" waves, take-off into the wind was impossible because the waves would break over the fore-deck and into the prop. I turned side on to the wind, and was off in 30' or so. Landing is a breeze, slow down, fly into the water.

Very tough little bird. Keep the tail light, mine's got almost 1/2oz lead in the nose.

J

old git

Hi J,

Thanks very much for the info and pics of your Aquastar, looking good.

I may get around to building one now, the previous posts, thoughts and modification didn't appeal. I've never flown off water since a rubber job in the early 50s.

It sounds as if it may be worth the trouble now someone has sorted out the problems. I sometimes wonder if all models are flown before they are kitted. If I were making a scratch build it is to be expected but kits are a short cut to avoid problems, I thought.




old git - - - - aka John L.

SharpProp

well in case anybody is interested I got her to run. And she runs quite nicely, Transitions fine....although I in the next couple of runs I would like to really push the time I let her idle. Just to seen how she transitions out of a long idle. I kept running into problems keeping the fuel lines on. what size fuel lines do you guys use with these engines.....or what method do you use to keep them attached? Maybe it was just the vibration of my "test stand" that was causing them to come off. I'm not 100% convinced that this engine is perfectly fine but I was feeling pretty good after the test run this weekend. I tried to put the tach on her but the florescent light in my garage was messing with the reading. So i guess i'll run through a couple more tanks then I'll put her on the plane and take her outside to get the rpm range. I'm guessing the RPMs should be between 6,000 and 20,000....?.?.?. Anyway now on to my next challenge. Covering the Texan. it's proving to be more difficult than I anticipated to keep the wing smooth. ug

Jburry

Well, Hey, where there's noise there's hope!

I've no idea what fuel or prop you're running, but that Aquastar above there is turning an APC 6x2 at 21,000rpm give or take, with a flight idle set at about 7000 RPM. It'll hold a bit lower, but I sacrifice low rpm's for reliability. I wanna boat back in under power. It's burning Sig Champion 25% fuel. It took alot of messing with the engine to understand how to hold an idle below about 10K.

For the fuel lines, I'm using standard medium line. I wasn't thrilled with it's holding power either, so I made small brass sleeves from brass tubing who's ID matched the OD of the tubing. Just a little 1/4" long piece of brass tube over the silicon, and it holds the nipple much better. I wish the carb inlet had a 2 barb nipple instead of a 1 barb one. On the test stand, I didn't bother, and never had problems, but I decided not to take the chance with it in the air.

I'm really glad you got'er running, hopefully it's got a life at least as long as the Texan's (may it too grow long in the tooth). Makes me sad to hear of any of these little marvels destroyed (unless it's being made into one of those cool radials...)

J

Falco250

The Bolink or actually Cmax .061 Revlite engine muffler requires two 1-inch long 4-40 bolts, and the crank requires a 5/8-inch long 5-40 bolt for propellor mounting as on a .049 COX. The Cmax muffler could also be replaced with a spare .061 AP or Norvel muffler and spring wire assembly.

The tall Cmax glow head can be replaced by any .049 COX compatible glow head such as AP, Norvel, Nelson, Turbo, etc. However the genuine COX glow head will require extra glow head gaskets to seat and seal properly inside the cylinder on account of interference from the higher neck on top of the Cmax cylinder head. The Cmax glow head could also be sawed between the 3rd and 4th fins, and the resulting top fin chopped to fit a suitable wrench.

The Cmax needle valve assembly could be replaced with a .061 Norvel C/L needle valve assembly or just the needle screw as they are completally interchangeable; that is if you prefer a longer needle screw, although I find the shorter Cmax one acceptable.

Falco250 ///