DeviousDave

I took a trip out to the Chicago area this weekend with a friend to pick up a bandsaw he 'won' on FeEbay-it was a good excuse to visit GKamysz and his family. I asked him about bringing some engines along to run if we had time as he has a nice test stand and a place the neighbors mind less than mine do. Took a handful, we got to run 3 and one of his converted 4 strokes. I didn't bother to get video of the Schlosser .25 as I posted some of that before here, and ran out of time to beat traffic (no such luck...) out of Chicago on the way home so some of what I brought didn't get bolted down to the stand.


http://s29.photobucket.com/albums/c2...cture003-1.mp4
First up is an MVVS .15. This is one of three I have, and was purchased used-I haven't run any of them so I figured I might as well give this one a go since it was probably broken in. After it was freed up it was apparent that it was a very low time engine and likely only had one or two runs on it. The settings weren't too far off, and we ran into a few snags but once Greg figured out what was what the engine was very easy to start. The first problem was that the muffler pressure was too great to lean the low end enough that it would transition well from idle. The air-bleed was all the way out and it still stumbled when opening the carb. The engine responded immediately to removing the muffler line and adjusting the air screw back to a more reasonable position.

This engine turned out to be a real sweetheart-I bought them because they are alleged to be powerful. I figured that the agricultural design of the casting and 'beefy' build would be indicative of what the engine would run like any time it wasn't running wide open-I was completely wrong about that. Instead of being a finicky, hard to set, or loud, it turned out to be easy to tune, powerful, and had a crisp and quiet exhaust note. You will note in the video that I had a hard time doing a one-hand restart, between the heat flashing off the prime and the engine not drawing much prime with the air bleed exposed, this was the only 'trouble' the engine gave. You just have to flip it fast while covering the intake and it fires right up. General handling qualities after being given 5-10 seconds to warm up were better than any glow .15 I have ever used. The prop we had mounted on it was a 9-4 APC, which is much larger than what I had envisioned putting on it, but it still turned a respectable RPM. I wish now that I hadn't waited to run the motor for so long-it's going to be a very competent sport motor.

http://s29.photobucket.com/albums/c2...cture004-1.mp4
The other engine was a well worn Norvel .061 Big Mig I picked up for a song at a swap show and put one of the new Norvel diesel heads on it. The engine looked like it had some time on it and happened to be the first I grabbed out of a box of 30 or so. Turns out the piston/liner is a little past it's prime, but that wasn't much of a factor. What was a factor was that the Norvel heads have a problem with thread interference. There is no relief at the bottom of the threads in the cylinder, and no chamfer/shoulder on the threads for the head so when you tighten either of the two heads I recieved, they would bind in the last thread and not seat the head. I knew something wasn't right when I installed the head and fired it a few times at home because the contrapiston had to be adjusted so far it was mechanically bound up before it would develop enough compression to fire on prime. I also had leaking. Prior to this weekend I had read in a test here that the solution to fix the leaking was to add another head gasket so I did that before I left. When I got to Chicago, it still leaked so I pulled the head and looked inside and saw aluminum shavings in the cylinder. Fortunately, Greg has a pretty well equipped machine shop at home and he was able to fix the heads in just a few minutes.

As for how the engine ran, quite well! Despite the cylinder/liner being past it's prime, the engine made good power and idled great. The prop was a Cox 6-4 grey competition, and I suspect the numbers in the video will be even better once on a new engine because what the video doesn't show is the subsequent starts where the engine made even better power for a few seconds until the liner heated up, and the carb was open considerably at a very low idle. What was remarkable to me was that the RPM and prop on this tired engine turn about the same speed as my glow Norvel .074 turns a similar prop on my JMG Penetrator. I'm going to shoot the Norvel importer an email about the head problem, they look to be pretty good performers once the clearance/interference problem is sorted.

Diesels are Fun!

123Cat

Nice video , thanks , looks like some strong running units , what planes do you plan ?

DeviousDave

I think the Norvel head will go on a new engine, and that will go in a RainDave SureShark. The MVVS, will go in a sport plane of some kind, probably a low wing with a high aspect ratio tapered wing. I'd like to do a fun/fast sport plane with a bagged balsa/foam wing, nothing fancy just something that will shake the fat with a 7-5 or so prop.

gkamysz

My Feedback: (19)

Yes, the MVVS 2.5D brought back some memories. I sure was lucky to experience it as one of my first diesels. The first was the MVVS 1.5D. Shoot, I should have dug it out and run it.

BTW, your MPJ is still here. i guess you'll have to come back for it.

DeviousDave

Doh-Go ahead and play with it!

Mr Cox

Thanks for sharing, I have one of those MVVS engines too but haven't run it yet. I was planning on putting one in a mustang but when I looked at the weight of the engine I was discouraged and the project was put away. They do sound nice though on their little pipe.

Also, I have to ask, which one of you is taking Diesel intravenously...?

gkamysz

My Feedback: (19)

A few milliliters a day keeps the psychotherapist away!

DeviousDave

Intravenously? Ha! They teach you in Survival School the best way to rehydrate a person is rectally![X(]

mylamo

My Feedback: (1)

Warm root beer

forsakenrider

Gross.

Did you hear back from Norvel about fixing the diesel heads? I would love to try one of those conversions!

DeviousDave

They asked what we did so I told him and he said they would make the changes to future heads. I just feel sorry for the folks who have them already...

forsakenrider

It is too bad for the heads that have gone out to people, but it sounds like this new group running norvel dont have thick skulls and thats great.

AMB

Use the Davis conversion no issue fits the 061 Norvel NOT THE 74 MARTIN

DeviousDave

I suspect the .074 will be the next head size Norvel makes-once the last threads are relieved on the heads they seem to be fine runners on the .061.

I'd certainly rather relieve a head once (Remember, Norvel has been made aware of the problem and will fix it) than buy a lifetime's worth of 'diesel discs'. I have several of Davis's heads, all bought second hand, new, and cheap. I just can't wrap my head around being held hostage to the teflon discs, even though I could make my own. Probably be better off with the Mecoa head.

steve111

Sorry Martin, I know you've keen on Davis stuff, but I've seen a Norvel 061 run with both the Davis head and the new NV one, and I'm afraid the NV won hands-down (didn't have any thread issues either). I've got nothing either for or against either product, and the Davis head was fine on a Cox 049 - it just didn't seem to suit the Norvel.

Mr Cox

The teflon disks are a bit ridiculous, and you risk to set the compression too high since they leak so easily...

DeviousDave

You might not have had any thread issues because you were probably running a larger prop. I could get mine to seal well enough to fire on the prime with a 6-4, and it probably would have been able to be tuned to get a clean running state, but I'm fairly certain that it would not have made the power it did and smaller props would not have been a possibility. With an 8-4 you'd probably never notice the thread problem....

earlwb

We have had a number of alcoholics die from alcohol poisoning because they ingest the alcohol rectally. The intestines absorb fluids much faster than drinking the stuff.So they get a high much faster and stronger that way. I think it takes the fun out of it if you can't taste the stuff. But then I am not a alcoholic though.


Anyway, back on subject, I haven't had any problems with the DDD teflon seals. But then I never tried one on a Norvel engine. One issue though is many guys are trying to crank up the compression too much to get more power, more speed, etc. In that case the excess compression stresses the teflon seal too much and they start to fail prematurely.

DeviousDave

I'd imagine that on a high RPM engine like a Norvel a teflon disc head would be less than ideal. Yes, you can bolt an 8-4 on a Big Mig but that's not really what the engines are for. A 6-4 or 5-5 is more like it-The problem is, that with the 6-4, the compression setting was pretty narrow (and this was with a dodgy piston/liner fit....) so smaller props than a 6-4 will be difficult to tune without blowing teflon seals.

Mr Cox

If you run a DDD head with a metal disk instead of a teflon disk you will get a much better seal and results. I've even had to trim down the counter piston because the seal was that much better with a metallic gasket and the counter piston bottomed out. That means that should the teflon disk had sealed properly the engine would have run overcompressed.

I really cannot see any good coming from using teflon. I have never had one fail due to a too high temperature, and a too high compression cannot "blow" the gasket in the traditional sense as a disk gasket is a continuous piece of material. The gaskets only fail because they get pinched off at the sealing surface, for me at least.

Traditional counter pistons work much better, and it is nice to see them offered for the little engines again.

Bill Adair

My Feedback: (1)

I tried one of the NV heads, but couldn't get a good compression seal even with four head gaskets installed. A friend fixed the problem by turning down a couple of the NV head threads on his lathe, using a 3mm screw to replace the compression screw so he could chuck it in his lathe.

Have not tried to run it since, but will report back as soon as I do.

Bill