Cranking and running Norvel engines

Rusty, Larry doesn't have anymore complete assemblies. I do believe he has a few needles. I would really like some more of them. Ken

Ken Cook wrote: Rusty, Larry doesn't have anymore complete assemblies. I do believe he has a few needles. I would really like some more of them. Ken

Needles are all I need. I hope he has some. I have an old Cox FT needle valve from a product backplate I can use to make one for my other Big MIg.

I don't know of any other source at this time outside of Larry and Texas Timers. Larry's NV bodies were nice since they could be bolted on; TT's are all press fit.

Larry found a needle that looks like mine and is mailing it to me. He said if it works, to send him a couple of bucks and a postage stamp. He's a good helpful gent. I get the idea he had to rummage around for it, so I'll send him more than he asked for. I'm going to cut the one I have short and thread a nut on top of the stub to grip it by. That should keep it clear of the ground.

I also cut a piece of latex bladder tube about 3/16" long and tried it as a gasket. It squished tightly into the joint, prevents the wobble and stops the air leak. The engine ran better than it ever has like this. I don't mind changing it for a fresh one every time I go fly. It only takes 2 minutes to change out to a fresh bladder. Another 2 minutes for the latex seal isn't a problem until I think of a better idea.

Oh, and the tiny retaining nut I lost, finally turned up in the dust pan when I was probing it with a magnet. I felt like I was panning for gold, about to give up hope when it arose gleaming from the dust. It's now back in place on the donor engine. Time to bolt it to the new Flite Streak!

The needle Larry sent works fine, identical to the old one, just not bent. I'll try not to do that. I'll look into making remote NVs for the Norvels too. On the TD you can snug the needle and lean it back so it just unscrews a bit in a minor impact, so it's not a problem. I can also shorten the Norvel needles too, as Ken explained how to do. That's well within my abilities.

I opened up the engine that crashed on the ReFried Bean and boy was it dirty inside. I'm glad I made sure not to rotate what was left of the prop. Judging by the marks in the prop's tip paint, it spun a lot of times kicking up dirt before the engine quit, and the cylinder was full of dirt and grass, but no scratches that I can see. I've never seen a Cox ingest that much garbage.

It's all taken apart for cleaning now . When I removed the piston, the wrist pin almost fell completely out. It passes freely through either side. I remember discussing that earlier in this thread about how to use a piece of 1/16" music wire to swage the opening and secure the pin a little better. There are no marks from it touching the cylinder wall though. I'll be gentle and careful with that. I want to get it back in the air soon. The other Flite Streak is waiting for it. I will NOT wreck that plane. Now that I better appreciate what a Big Mig can do, I'll be more prepared.

I also have a big 30 something inch slat winged plane that was given to me, with another of these engines on it. I don't know if it has a name or not. He said he built it from magazine plans. I'll post a picture of it. That engine turns freely. He said it did loops pretty good but not much else. It might make a good trainer, which I've been wanting, for friends to fly, since the old Stuntman is pretty much worn out. Friends and family have beat it down to glue and splinters.

What is wrong with the stock needle on the Norvel?
If it is too long, just cut it off. Some also came without the extra piece of wire.

Neither needles work correctly using a bladder. Even the AME that comes without the wire doesn't have a fine enough adjustment to get a decent run from a bladder. On the other hand, the needle works terrific using crank pressure. Ken

Yeah, that.^^ I use bladders Kris.
Here's the one I am referring to. It sticks up into the danger zone.



I'm going to cut it to a stub and thread or solder a nut onto the tip.

Okey, I've only used the RC versions myself and if/when the carbs are properly sealed there are no problems finding a stable needle setting.

It's been a while since I updated this thread, or messed with a Norvel but I've been meaning to update one thing. My first Big Mig, which I got new and un-run had a wrist pin that would slide freely out of one side of the piston. I was worried about it galling the cylinder wall but ran it anyway, flying the ReFried Bean, and it ran really smooth and fast. But since I busted the wing and buried the engine in the dirt I had to take it apart to clean it. This was an opportunity to fix the sliding wrist pin. I followed the instructions that either Fit90-Bob or Andrew(or both) gave me and locked it in place.

I cut a short piece of 1/16" music wire and laid the piston on a block of pine. I placed the music wire in the groove on the side of the piston where the original swaged dent that retained the pin was hammered into the skirt. I used a tack hammer and lightly tapped the wire two times and checked it. The pin would no longer pass through the hole and there was no raised ridge that could gall the cylinder wall. I cranked and ran it. There was no evidence of scratching on the cylinder and now I'm happy to have one more successful thing in my list of Norvel things to know.

It's nice when things come together. Thanks for the update Rusty.

Yesterday I was test running a Big Mig using Sig 35 and a 5" MA prop. This one isn't completely broken in yet so it's not quite up to full speed, running at about 22.5k RPMs(I have another that runs at 28.8k with a 5.5x2.5 APC). I wanted to see how much different fuel affected the needle setting, so I filled it with Glowplugboy 24%. Maybe closer to 22% since I had spiked it with extra oil, but it ran at 23.5K RPMs. I had 3 shims with the stock Norvel head and plug. It needed a slightly richer setting, and wavered a bit when the bladder got down to the last quarter full, which the 35% didn't do. That was completely unexpected considering the higher nitro of the Sig and the fact that the 50% synthetic is slicker than the pure castor in the GPB fuel.

Just shows that synthetic oils and more nitro isn't the solution to everything.

I only use full castor in non-ballbearing engines. Norvel engines can also be a bit on the tight side for the fit between the crank and crankcase when new, so they improve with running time. An improtant factor is the compression setting for each fuel, ideally you should optimise the the compression setting for each fuel before comparing the performance numbers. Both the Nitro level and oil contents will affect the optimum number of shims. Ideally we should have had adjustable compression abilities on glow engines, just we have on diesel...

Ah Utopia

Shangri La

and

The Playboy Mansion

Just a teaser then while you are looking for those other places;

I took the new BFS out to fly today. I'll detail those antics in another thread with videos. Also videoed the Lil Satan with a really good running Tee Dee.

But here's something about the Big Mig. I got a bunch of flights. Each one needed a tiny bit different needle setting but all ran well except one. It leaned out in the air and ran slow. All the time I was worried about overheating it, but it stayed steady for the full flight. My worry is that it was a really long run, almost 5 minutes. I was afraid I had damaged it, but it ran fine after I cranked and needled it for the next flight. I haven't had a chance to look at the piston top and cylinder yet. Are they as easy to damage by running lean as a Cox, or do you think I didn't hurt it? This is the one that is still pretty new, only bench run and about 10 or 12 flights on it.

I don't know what happens with synthetic oils but with castor oil they can take a lean run without any problems.

Surfer_kris wrote:I don't know what happens with synthetic oils but with castor oil they can take a lean run without any problems.

Today I'll open the head and see if the piston top looks scorched. Not much I can do about it now except just be more careful. I'm learning that when you change the needle setting on a Norvel(maybe just on bladder pressure?) it gradually changes and you have to wait to see how it settles down before re-adjusting or launching. Or if flooded it takes a long time for the excess fuel to burn off. On Coxes the result of an adjustment is instant and obvious.

I think Norvel engines are less sensitive to a lean setting, compared most other engines, and that also gives them an excellent milage. It also means that they give less clear signals to a lean setting, you could try using a tach to check max revs and back of from there. Otherwise, small adjustments and flight-tests are the key.

RknRusty wrote:

Surfer_kris wrote:I don't know what happens with synthetic oils but with castor oil they can take a lean run without any problems.

Today I'll open the head and see if the piston top looks scorched. Not much I can do about it now except just be more careful. .........

Rusty -
Below is an excerpt from the original NORVEL fuel FAQ. Note that the NORVELs are actually designed to run on lower nitro levels (typical of most European engines) and that 15% is sufficient. They don't necessarily recommend 35% unless you're going for higher performance. I run 22.5% N; 21.25% oil with a total castor content of 17%. With the extended fin area on the Revlites, you have a lot of cooling capacity, so lean runs with a good castor content fuel are not as critical. Realistically, the fin area/displacement ratio on the Revlite engines is likely one of the highest among model engines.

Fuel FAQ:

The ideal nitromethane content is somewhat difficult to nail down. Lower nitro content fuel can run very fast, but finding the correct needle setting is more difficult, and a higher compression ratio is needed. The NORVEL engines were designed in Russia where nitromethane is extremely difficult (and illegal) to buy. As a result, the engines run perfectly well with no nitro at all or very little nitro.
Nitro gives you ease of starting, especially in cold weather, and generally, a broader range of acceptable needle valve settings. For racing situations, there is no question that more Nitro means more power. Generally, 10% to 15% nitro is good for sport flying and general purposes.

As your applications become more critical, the nitro content should be raised. As a practical limit, stay below 35% Nitro, or the wear rate and potential for damage to the engine become excessive. We know that competitors use up to 65% nitro fuels, but they are willing to replace an engine each flight if that is what is needed to win.

Thanks for the replies. I looked inside and the top of the piston looks normal and the pinch feels tight and normal. When I run out of Sig 35 I will probably run Glowplugboy with lower nitro. It runs faster with that than the Sig anyway. Funny how I try other fuels and always come back to GPB. I have an old bottle of Norvel fuel with 15% nitro and 18% castor. I have no idea how old, maybe decades, so I'll probably leave it alone. If I use it I'll filter it first.

RknRusty wrote: I have an old bottle of Norvel fuel with 15% nitro and 18% castor. I have no idea how old, maybe decades, so I'll probably leave it alone. If I use it I'll filter it first.

If the cap is on tight it should be OK.

George

I tore down an old Big Mig .061 to clean and inspect it. This is the cruddiest looking of the three I own and the piston top was blue like maybe it had been overheated. It has a really tight pinch and the compression feels just fine to me, but a couple of things bother me that I want to ask about.

First off, other than the discoloration, what's wrong with this picture?

Shouldn't the oil hole be on the other side? If not, I need to open up my current runner and change this.

Here's the top of the piston and the liner. The liner looks okay, but I don't know if you can judge it by sight or not.


Here's the liner.(oops made it too big, click the thumbnail)


Just curious. After I get a reply about the oil hole in the con rod, I'll put it back together and run it. It'll probably be fine for my uses.
Thanks,
Rusty