Cranking and running Norvel engines

daddyo wrote:Thanks fredvon4, very interesting technique. Is it possible for some reason the Norvels have a problem starting like that, maybe the prime blows out the intake?

fredvon4 wrote:daddyo

welcome to the forum

Rusty was doing a starting technique we call compression bump starting and works fairly well on many high compression engines. You are correct normal rotation is counter clockwise for most engines and propellers.

Turning the prop clockwise (backwards) the piston will come up on compression and try to fire early and send it back in the right rotation much faster then you can hand flip it. Most of the time it will start right off.

I have two SuperTiger engines a .61 and a .90 that I prime the carb with four turns of prop with finger over venturi, put glow clip on, grab the spinner and flip clockwise and they fire counterclockwise almost every time in warm Texas weather. On a cold morning I electric start

If you are referring to the quote above, it's not specifically a Norvel thing, it's a high compression thing.
If you try to crank it in the normal running direction, you are pushing it relatively slowly through the compression stroke, and if it doesn't fire, it has no momentum to approach TDC on the next turn because there is too much pinch and compression. But if you bump it backwards it has enough momentum to compress the prime enough to ignite right before TDC. It blows it back down in the other direction and it's off to the races. Once it begins to warm up, the cylinder expands and relieves the cold-pinch, freeing the piston up even more.

That cold-pinch is why you do not want to flip the prop over unnecessarily on a brand new engine or piston/liner. The castor oil an cold spinning recommendation that NV proposes to help first cranking probably helps some, and so does heating. But I was a complete novice with flipping off a tight new engine and ended up looking like a frustrated moron trying to get my first cranks out of the way.

I had only been running Tee Dees for less than a year at that time and I was almost as stupified by them at first. Now that I got the hang of knowing when a Tee Dee is flooded and when it needs a prime, I can't imagine needing a spring any more, and I still flip them in the direction of normal rotation to crank. The Big Mig that started this whole thread still hasn't had a chance to loosen up completely so it still has a spring on it, awaiting it's first ride, which is almost ready(the Re-Fried Bean). Before I mount the old greaser(my new old broken-in Big Mig) on it's Baby Flite Streak, I will practice flip starting it, and I expect I'll similarly be thinking, What was all that ridiculous fuss about.

Thanks all for humoring my slight hijack of Rusty's thread. I learned a lot and have a new Big Mig 061 from NV on the way for my stocking.

FYI to Surfer_kris and please do not take this as a snotty shot. Here in America most (not all) of the time the secondary supplier of many items buys in bulk and has significantly lower prices than buying directly from the "source".

As I could not find information anywhere on the NV site about exactly where they ship from I had an additional concern. I buy quite a bit of foreign sourced items for several of my interests and hobbies. Finding the USA outlet usually ends up less expensive just in shipping costs.

Years ago Super Tiger sold directly and through licensed distributers. Buying one each G90 from ST for $149 was dumb as the same item frequently went on sale at Tower Hobbies for $109. Tower could do this as they bought in bulk.

All that said I could not find a USA hobbie outlet that has any stock of NV engines so I pulled the trigger and PayPal a new engien that is already shipped...

Thanks to all for the excellent advise and information, I love this site and members

fredvon4 wrote:Thanks all for humoring my slight hijack of Rusty's thread. I learned a lot and have a new Big Mig 061 from NV on the way for my stocking.

No problem, Fred, it's not a hijack. I even changed the title so it's not "Rusty" centric anymore. Since more of us are interested in Norvels, it can be our general Norvel information sharing thread.

Earlier I said I was going to practice flip starting the ol' Greaser before I mount it on Flite Streak II. It was still on the stand from the post cleaning run last weekend. I took off the APC for my own safety, and also to see what speed it turns for my flying setup with a MA 6x3. I fueled it up, primed the exhaust and gave it one whack with a chicken stick and it was off and running. Okay then, no spring needed. So that confirms what everyone has been telling me; when a Norvel is broken in, it is actually very friendly to crank. Since I have a spare spring, I'll install it anyway just to help clear floods. I think I'll feed the engine with a party balloon for the maiden voyage. If it isn't happy with that I'll fit it with an NV for pressure later.

Soon this old .061 will be flying the Streak II. The only problems with this plane are the elevator doesn't move far enough down before the bellcrank hits the rib. That leaves me with two options. One is to use the closest hole in the horn and solder a stop on the rod where it passes through a guide eyelet(which it also needs) to restrict the Up throw. That might make it too twitchy for my taste. The other option is to cut open the covering and cut a relief in the rib that's the real problem. I'll just have to put a different colored patch on the wing.

Its other problem is some of the sealer, or whatever it is, is separating along the fillets on the wing root. I hope the glue inside is not falling apart. I'll just paint some thin epoxy along the fillet and call it done. I have no idea how old this model is. It appears to have only flown a maiden, crashed and then was stored. Probably because it didn't fly worth a crap with the wonky elevator.

My Big Mig arrived. Without scanning back through ten pages can someone tell me the dia, thread, and length I need for longer Head/Cylinder bolts and a source please

I know Andrew or Fit90Bob knows. Ken probably does too. I'm about to go on the NV site to find out what size the venturi nut is because I just shot mine across the shop this afternoon. So I'll see if I can find that too.

Dubro 2mmx4 socket head screws part# DUB2111. They can more than likely be found at any hobby shop carrying r/c cars. Ken

I prefer to use 2x8 mm socket head screws. Standard pitch is 0.4mm .

The additional length allows the screw to extend below the mounting flange at the top of the case. If you ever snap a screw off flush with the top of the flange, they can be almost impossible to get out. By allowing them to extend below the flange, you can grasp it with long nose pliers and turn it out the bottom of the flange.

I buy mine in bulk thru McMaster-Carr. Black alloy is $8.76/100 count. Most folks don't need that many, but for me, it's less expensive in the long run.

andrew

Anyone know the size of the venturi retaining bolt and nut? Maybe the same threads as the head bolts.

Rusty --

The retainer nut is 2mm, same as the cylinder screws.

Thanks Andrew. I'm going to get down on the floor with a magnet. It's down there somewhere. But I better get some spares. The venturi is stuck so tightly on the old engine that I borrowed one from, it would probably stay on without it if I just block the screw holes. It's like someone glued it on, but I don't think it's one of the old ones that came that way.

I finally got my new Big Mig loosened up to where it flip starts easily without the spring. It's mounted and ready to maiden on the Refried Bean now. Sunday's forecast is for 70F and no wind at all. That's rare. I can't wait. Hopefully I'll have a fun flight report with video.

Just a comment on the prop size, I find that a 6x3 is the max prop load they can handle/like. it should do +18000rpm on that prop but they are much happier on a smaller prop load. It is at +20000 rpm that they come alive. There is a 5x4 from cox, not the large area one but a softer one with a smaller area, that works well. For CL you could also try with a 6x2 prop.

RknRusty wrote:...The venturi is stuck so tightly on the old engine that I borrowed one from, it would probably stay on without it if I just block the screw holes. It's like someone glued it on, but I don't think it's one of the old ones that came that way.

All of mine that are epoxied-on do not have screw holes. My Revlite venturies are held on with screws.

George

gcb wrote:
All of mine that are epoxied-on do not have screw holes. My Revlite venturies are held on with screws.
George

George --
I have had some engines with carb screws that seemed to have some kind of sealant -- it was almost like a lacquer, very thin, but did require some effort to pop the throttle body off the case.

The venturi on my newer engine is loose. I've replaced the gasket with a new one from NV, and made a thicker one from fuel tube with no luck. In preparation for today's flight, I Permatexed it with a Norvel gasket. It ran good for a while but after a few flights it was leaking again. The screw holes in the venturi must be too big to pinch it down on the gasket. I'm going to JB Weld it on before I fly again.

Andrew, you are right about the 6x3 prop. It ran pretty good but not the blinding speed I expected. It wouldn't let me launch rich at all and cut off in the air once when I tried to. With a higher RPM prop, I bet that wouldn't be a problem. If I launched at full RPM it flew strong and didn't bog at all in the loops until the venturi started leaking.

Rusty, I wouldn't JB weld that in there. Double the gasket if needed. JB weld is tough to remove if you need to. I had one of the epoxied ones come loose and I cleaned it an JB welded it back in. Recently I wanted to remove it entirely and do the mod like I pictured a little while ago of having the Cox spray bar pressed in. It won't come out. I had the heat gun on it for a while. I'm sure a torch will remove it. I just left it as is for now. Ken

RknRusty wrote:The venturi on my newer engine is loose. I've replaced the gasket with a new one from NV, and made a thicker one from fuel tube with no luck. In preparation for today's flight, I Permatexed it with a Norvel gasket. It ran good for a while but after a few flights it was leaking again. The screw holes in the venturi must be too big to pinch it down on the gasket. I'm going to JB Weld it on before I fly again.

Rusty -
I'm in agreement with Ken about JB Weld. Done correctly, it's amost impossible to break loose. Make your tubing gaskets a little thicker; I'm not a real fan of the NV gaskets. Sometimes they are hard and if you have any excess play, they may not be thick enough. If NV is still selling off old stock, their Orings may be older and have hardened or oxidized over time.

If you can get your hands on some 1/4" surgical tubing, you can cut a piece large enough to fit over the carb mounting screw -- that should help seal any leaks. Also, be sure you have a piece of fuel tubing over the NV --- the NORVEL is not too prone to leaking, but I add one out of general principals.

A MA 6x3 cut back to 5.25 or 5.5 will ready be better. The NORVELs are ported to wind up to be really happy. They are also not very sensitive to the needle. I try to launch on the rich side of full RPM.

Are you running muffler pressure on the tank? One other thing, be sure the check the muffler/stinger cap. I've had them rotate and, in one case, had the cap pop loose in flight. Usually, I decide the direction i want the stinger to point, then I do use JB Weld to hold it in place. If the cap does come loose in flight, you can lose it or the muffler body.

I also found that only certain forms of Permatex are NOT fuel proof to alcohol. I found that Ultra Blue held up fair while Ultra Black almost immediately dissolved. I posted this before, Permatex Anaerobic gasket maker is formulated to be used with aluminum and doesn't dissolve in alcohol. It only dries in an enclosed environment. Anything on the outside will never dry and will wipe clean with a rag. If applied around the perimeter of the venturi it will solidify but, it does come apart as it was designed to be service removeable . In addition, this material doesn't give off acetic acid like some of the RTV gasket makers so it will not corrode aluminum or steel. Ken

Okay, thanks for the tips. No JB. I'll try making a thicker gasket.

Andrew I have a fine thread NV on it with a lock nut to hold it in the position, but just loose enough to tweak. Now that it's bent I'll have to find another one that will work with the lock nut. It's one of the stubby black L shaped needles. Fit90 gave it to me, so I'll see where he got it. I'm not running a tank. I'm using a pressurized surgical tubing bladder, same as on the Tee Dees on my Streak, Li'l Satan, and Stuntman23.

Also I have an APC 6x2 and a 5.5x2, as well as a 2.5" pitch on one of those sizes. I might try one of those. I keep a spare MA 5.5x3, 5.25x3, and 5x3 in my box too.

Ken Cook wrote: I also found that only certain forms of Permatex are NOT fuel proof to alcohol. I found that Ultra Blue held up fair while Ultra Black almost immediately dissolved. I posted this before, Permatex Anaerobic gasket maker is formulated to be used with aluminum and doesn't dissolve in alcohol. It only dries in an enclosed environment. Anything on the outside will never dry and will wipe clean with a rag. If applied around the perimeter of the venturi it will solidify but, it does come apart as it was designed to be service removeable . In addition, this material doesn't give off acetic acid like some of the RTV gasket makers so it will not corrode aluminum or steel. Ken

I wish I remembered having read that before, but... too much nitromethane absorption, you know. Anyway, you're sure right about that. My engine was drinking a slurry of melted RTV on Sunday. That might explain why the engine ran so damn good on the first flight, and fell off after that. I was not embellishing my story(in the Refried Bean thread) when I said the engine didn't bog in the loops on the maiden flight. It was hot and tight and made me smile.

But later I could see bubbling around the joint and the venturi was gradually back to its old loose self, and it looks like air wasn't the only thing affecting it. I took it apart today and there were black streaks of goo in the throat and a foreign bump hardened on the glow element. The element looked otherwise clean, but I think I slightly traumatized it trying to pick the bump off of the coil. It still lights with electrical current, even the zit glows, but I bet the methanol catalyst doesn't light it up in that spot. So I swapped it with the better looking one from my other engine.

While I was at it I compared it to the Merlin drop-ins that Bernie sells. To my eyes, the combustion chamber is identical, and so is the size of the hole that surrounds the element. But the Merlin coil is thinner and smaller. It's advertised as Medium, so it looks like the Norvel is a colder plug with a big fat coil. Since I run about 20-25% nitro I suppose a medium will be fine if I have to start using Bernie's plugs. On the other hand, my full bore style of flying demands a hot engine run, so I'll have to decide what holds up best. But I digress...

I used acetone to clean the Permatex off and clean out the throat. I'll do as Andrew suggests and wrap a section of latex tube around the whole outside of the venturi joint. I put a good thick silicone washer back in it and squeezed it back together and installed the screw. It'll run fine like that, even though the thing still wobbles when I'm adjusting the needle. It's tightened down with the lock nut now at the position it ran best with, so I won't have to fiddle with it much.

The only thing I need an answer for at this point is, where do I get some spare fine thread needles like the one that's in it? The KK needles don't fit. I haven't measured the diameter yet. I'll do that next time I go out to the shop. When I get some spares, I'll do what Ken described to shorten it. It needs to be very short to be clear of the ground in case of another upside down landing.

Here's what the needle looks like. This one has been bent 90 degrees and straightened back out, so it's weak now, but still works.

Rusty,

Glad to hear it is flying. Sorry I haven't been aound in a while. That NVA came from kittingittogether.com. Great place to deal with.

Bob

RknRusty wrote:
While I was at it I compared it to the Merlin drop-ins that Bernie sells. To my eyes, the combustion chamber is identical, and so is the size of the hole that surrounds the element. But the Merlin coil is thinner and smaller. It's advertised as Medium, so it looks like the Norvel is a colder plug with a big fat coil. Since I run about 20-25% nitro I suppose a medium will be fine if I have to start using Bernie's plugs. On the other hand, my full bore style of flying demands a hot engine run, so I'll have to decide what holds up best. But I digress...

Rusty --
You might consider a Galbreath head/NELSON plug combo. Generally, this combo will perform better than the original NORVEL plug; the drop-ins are a little down on performance and a standard plug will cost you even more RPM's. The NELSON plug is tough and long lasting and it's design was created for the Formula 1 and Q40 pylon racers. Doug Galbreath designed the head for Tee Dee .049's and .051's used in free flight competitions. The idea in these contests is to get as high as possible on a timed run, so you want every RPM the engine can produce. The higher you are, the longer you have to glide down.

The head and plugs are available from Larry Driskill (his 1/2A C/L combat design won in 3 separate NATS) at http://kittingittogether.com/glow-plugs/ He is a top notch guy to deal with; he was also a U-2 pilot.

You will want the NELSON HD, not the NELSON hot. BTW, the Galbreath head fits both the NORVEL and COX engines. On occasion, you may need additional head shims/gaskets. These are also available on Larry's site. Adding a pack or two won't change shipping.

fit90 wrote:Rusty,

Glad to hear it is flying. Sorry I haven't been aound in a while. That NVA came from kittingittogether.com. Great place to deal with.

Bob

Excellent! I'm on it.
Thanks Bob, and Andrew too. I have a Galbreath head and a couple of the Nelson plugs too. I'll give them a try.