News:



Advertise Here

  • August 19, 2019, 08:01:55 PM

Login with username, password and session length

Author Topic: A wealth of engines  (Read 502 times)

Online Mark Mc

  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 466
A wealth of engines
« on: January 19, 2019, 11:15:04 PM »
I was cleaning my workroom this evening and consolidating engines into bins.  It seems that I have three Norvel .074s, three helicopter .061s, three standard CL .061s, and an R/C BigMig .061.  The only difference I can see physically between the heli engine and the standard CL engine is that the standard engine NVA is angled and the bosses are shaped a little different.  Does anyone know of any differences in the performance of these two engines?

Mark


Offline kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1211
Re: A wealth of engines
« Reply #1 on: January 20, 2019, 07:47:44 AM »
             Mark, there's been many many renditions of the Norvel engines. Cylinder differences,piston differences,  porting differences, venturi differences. There's also crank shaft differences where the web of the shaft has been lightened on the perimeter of the crank web while others are solid. Deck heights of the case are all over the place with these so you could own two identical engines and they perform differently. I have seen a lot more differences with older versions than the latest versions.

  So to ask a question in regards to performance, it's not exactly fair to offer rpm mentions unless one knows exactly what you have. Just looking at the top view of the two engines shown, I can tell you there's a immediate difference between the two needle valves. They both operate differently due to needle shape. I have had good success with the version on the left but the version on the right has been questionable at times depending on when it was made. As soon as the needle gets the engine leaning up, it cuts off fuel supply and falls off rapidly as if the taper is too aggressive. Some work, some don't work .

            The other is what you desire to use the engines for. You can't assume that the engine is what came in the box or packaging. Norvel was notorious for mixing this up especially the Revlite versions that came in the red. white boxing. It was so bad, that they were selling these engines at $20 a piece to get rid of them, units that came in damaged boxes were $5 cheaper. I acquired 10 of them at these prices and as mentioned, incorrect instruction manuals, parts were mix matched, AME's were in Big Mig boxing. You need to remove the glow plug and count the port holes in the cylinder. 5 small ports for a Big Mig, 3 larger ports for a AME.

 A HUGE problem with the AME is the wrist pin. If one had a used engine it might not be fair to assess the engine unless one is insured that it doesn't have a score in the cylinder.  The wrist pins are staked on these engines. When the piston wears, the staking is compromised and the wrist pin slides fore and aft. The wrist pin hole on the AME version lines up with the porting hole in the cylinder. This can score the cylinder and it can get caught in the port hole if it slides into it. This can't happen on the Big Mig as the cylinder holes don't line up.

        AME engines are not going to run properly on suction, the venturi is too large, and it will run best on bladder however many successfully ran them on muffler pressure. Norvel did make a backplate for crank pressure but the hole in the pressure nipple was  too large for it too work like it should. The screen cap on top of the ventui is difficult to remove on the  older versions which makes it difficult to determine venturi sizing. The older Norvel's like you pictured on the left also have their ventui glued into the case. This is a area that needs to be addressed or problems will occur. Removing it,cleaning it, and gluing it neatly back in with JB weld resolves any problems. The Revlite versions mainly had their venturi's bolted in with a oval shaped o-ring under it.  All of this is relevant because one can't offer performance statistics until these issues are not a issue. Don't tear it apart, just insure that it's tight and the venturi is not wiggling. If the venturi is wiggling it's sucking air and  it will become looser and the threads on the through bolt will chew the case up in short order.

         I have found the left engine with the squarish cylinder head style which I believe is ABN to be a very pleasing  engine. I really appreciate the right cylindrical style Revlite versions but they require some techniques in breaking that unless followed  can determine a short  lifespan if one is not familiar with them.

       I have two heli .061's, the differences on mine are quite different as the heli .061 had a bronze bushing in the case which was fit quite tight and requires lots of break in time to loosen things up. The venturi in my opinion was also quite small and I have opened that up a bit. I'm starting to see rpm numbers that are more in my favor for what I'm using them for. I also had the case honed to eliminate running the engine a bazillion times to run it in.

          Seeing that you have so many of them, I would run them all and document their engine rpm's between all of them and determine which of what you have starts the easiest. This will certainly ease making a choice of which one to use later on.


          Just another note, the engine on the right is using a Merlin plug. Different head styles can offer a 500-800 rpm increase over the stock unit.  I personally haven't had a real positive experience using the Merlin plugs in the Norvel. Many have, but not me. That plug requires 4-5 additional head gaskets to work. I have had that plug do funny things that I don't care for. I have had it start without the battery connected and I have had it backfire instantly when the battery was connected to it. It's a very hot plug in my opinion too hot. I never understood why Merlin offered a hot plug for the standard 1/2A drop in element. I contacted Al in regards to this as he offered the blue insulated version for 1/2A r/c. Too me, the colors are backwards. The blue being cooler in my opinion would be associated with high nitro fuel where the red indicates hotter for lower nitro fuels and better idling characteristics. I strictly use Nelson plugs in these engines and have no reason to try anything else, they're the most inexpensive plug not to mention the most durable and reliable.




Online Mark Mc

  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 466
Re: A wealth of engines
« Reply #2 on: January 21, 2019, 12:01:24 PM »
Kenneth,

Thanks for taking the time to write out such an informative post.  I greatly appreciate it.  I have a vague understanding of the various iterations of the Norvel.  What I have is what I've picked up over time from various sources.  I've never bought a .061 new.  When the weather dries out, I'll do a proper break-n on these, even though half are already used.  The venturis and screen housings feel tight, but I haven't really tried to pull them off.  I'll check them to ensure they're all on tight.  I wasn't sure if the heli versions would be great for airplanes, but was ready to give them the benefit of the doubt.  Hopefully this year I'll have planes for five of the engines.  See my thread on my long term build of all five Little Legends.  The three dedicated plane engines will get the first attention. 

I'll see how the needles fit and work.  On the heli engines, I was playing with the idea of installing fine needle valve assemblies to see how they run, so your statement that they may not needle well works with that idea.  I was thinking about going bladder fed on these engines to avoid messing with trying to find the best suction feed set-up.  Not necessarily to get the max RPM out of them, just the most consistent feed.

Hmmm...  I didn't know about the wrist pins.  I'll take a look.  In fact, I guess I should take them all apart and ensure they're clean and defect free.

As for the plugs, what came with them is what's on them now.  I was kind of thinking about ordering Nelson heads to outfit 5 of them and going that route, but we'll see.

Thanks for your time and help,
Mark

Offline kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1211
Re: A wealth of engines
« Reply #3 on: January 21, 2019, 02:41:44 PM »
          Mark, the Big Mig engines run terrific on suction and no need for muffler or bladder pressure. However, if you do use the muffler, you will be happy with both the power and noise reduction. The Big Mig runs well on 10% fuel which is a very nice feature over a Cox engine. Wrist pin concerns would be only the AME 3 ported engines and this doesn't happen within a few runs. If you do happen to have one and you take it apart, just note any funny business on the staked area. If your venturi's are all tight, your good to go. The newer Revlite with the bolted venturi is the one that can get loose and the o-ring under it is specific as a standard round one is a no go.

       My heli engines as I mentioned differ from what I see in your pic. Mine had the large finned head and very tall venturi stack. Mine didn't come with a drive washer for a propeller. I had to have them fabricated and I did this using a round hole and a set screw which bottoms on the flat of the crank. These are great little engines and they won't dissapoint.

           Mark, if your not familiar with these engine, the  APC 5.5x2, 5.5x 2.5, 6x2, 5x3, 5.7x3 are all good choices each one offers a lot of difference and they don't break the bank buying them. I have successfully used the older Grish white tornado props in various pitches even some that were 4 pitch and I feel they worked well due to narrow blade area over a Cox prop.


Advertise Here
Tags:
 


Advertise Here