Agreed, but we also need to recognise the damage a public badmouthing can do to a small company. (I'm talking in general terms here, not having a go at anyone involved with this thread). There is also the danger of people complaining publicly when they haven't operated the thing correctly in the first place. It's not as if we're overburdened with people turning out good stuff like Norvels, Enyas, and the like, and we need to be a bit careful or we'll all find ourselves using Chinese electric motors.

My policy is that if I have a problem, I'll give the manufacturer the chance to sort it out. If it's handled properly, then great - end of story. If not, that's when I won't mind going public with it.

Alex, do you need help fixing the heads you have on hand?

Yes, and when Sig was handling Norvel, you could not ask for better service and unquestioned replacement. When Sig was getting out of Norvel, I had the chance to buy all of their returns just for the good parts I could salvage. Again, this was to be a labour of love enterprise to provide parts to those who would need them. That's before Alex came along. But anyway, you would not believe the abuse some of the engines got and still, Sig honoured warranties just to keep the good name of Sig and Norvel.

I must have enough parts to make a half dozen .15s and a few .40s. In any case, I hope to get back to tinkering this winter. First up will be the on the fly, adjustable compression, glow .15 that will be used to investigate a hybrid fuel that I hope can contribute to eliminating ether. I hear that some one, (Enya?) has come up with a glow plug engine that will run on gasoline, so there's room for some real experimental fun here.

Magnum announced a .52 glow type engine that runs on gas and spark, but they have missed a few release dates and aren't talking about it much anymore. One or two went out for testing, but other than a few YouTube vids nothing has been said about it for 2 years. They probably have run into problems they weren't anticipating and are having a hard time getting past them.

We figured out what was wrong with these heads when Dave was here while testing the heads a couple months ago. It's a easy fix, if you have the right tools. To me the issue is the the seeming lack of testing of the parts at the factory and the lack of familiarity of the designer with the components. The recommended fixes and and fixes performed at the distributor also show the same problems. The fact that you have to register to look at a product the company wants to sell to me, has turned me away from the beginning.

Small business should be more aware than anyone that sending defective product will result in their demise. Sure we are in the same boat, but one of use is reaping the benefits and the other has take what we get. If not spending my money avoids aggravation, so be it. I'll stay on shore and watch the boat sink. Having worked in the hobby industry and watched companies make poor decisions, it's really nothing new.

Quite honestly, I ran into the same issue when I made my first Norvel diesel head. I knew I needed a relief on the nose of the thread, but I didn't know exactly how much and was short by a few 0.1mm. Fortunately, proper testing lead me to the issue. If it were my engine design things would be different, but that's not relevant.

Here, http://www.rcuniverse.com/forum/m_10...m.htm#10741432 I've started a thread about the Enya that uses a glow plug and gasoline for fuel with no methanol in sight. We know that gasoline can be used with a glow plug as long as there's some methanol in it to let the catalytic reaction to take place. The gasser guys have been doing this for years. They also run the usual 40 to 1 and even 100 to one oil because gassers have bearings on the rod.

This Enya has the usual bushings so it appears that the oil is the key in that respect. This MAY allow us to mix a methanol based fuel at very low oil percentages. That will mean more power and mileage.

I have the glow plugs and fuel on the way and will get started immediately and report back. I will also, naturally, try the oil in a diesel mix. Perhaps 20% ether, 70% kerosene, 2% CB and just 8% oil.

Norvels are notorious for having better mileage than any other engine due to the nature of the unique metallurgy. Diesels on their own are not thirsty engines and add to that this special mix and who knows?

http://www.nvengines.com/index.php?o...mart&Itemid=67

I had to smile at the advertising copy under the diesel conversion head photograph.

"High maintenance "O" rings" ?

Some of us like "O" ring sealed contra pistons. Some of us prefer traditonal lapped set ups. Most of us probably don't care. One thing though - I've never heard of "O" ring sealed contra pistons described as "high maintenance"; at least not the viton "O" ring type which has been preferred for decades.

Somewhere I read of early, O-ringed contra-pistons that used silicone O-rings. Perhaps mistakenly assuming that the high heat resistance of silicone was necessary. Viton and even Buna-N O-rings are plenty heat resistant in diesel operation. Perhaps this is what they are using.


Silicone swells in the presence of diesel fuel. That would explain the high maintenance.

Andy,

My first diesel engine was a McCoy .049, purchased soon after they were introduced.

I taught myself how to start and run that diesel engine, on fuel I mixed in the basement. While I was teaching myself, and several friends to fly control line with a Walker Firebaby, I noticed the engine was getting harder to start. When I pulled the screw on head muff, I found a mess of rubber pulp gumming up the top of the contra piston. Pulled the contra piston out, and discovered that the O ring was worn flat on the outside! It was a soft white material back when silicone rubber was still a dream, so I'm pretty sure it was rubber.

I wrote the McCoy company, and asked if replacements rings were available. The response I got was a nice letter, and a small bag of new O rings at no charge! Never did use them all, and sent them to an English pen pal along with the engine shortly after.

My pen pal was a master machinist, and made a new metal contra for the McCoy, and was very pleased with it.

I now have three McCoy .049 diesels to replace the one I gave away, and the two I've run with Bunna-N O rings from ACE Hardware run fine, and the rings seem to last a long time. The third is a newer model with beam mounts, and is still new.

Some day I may try Viton O rings, but so far have not had reason to switch.

Bill