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Norvel .061 Diesel Conversion?

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Norvel .061 Diesel Conversion?

Old 04-04-2003, 03:42 AM
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PeterH
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Default Norvel .061 Diesel Conversion?

I have an earlier-series (small fin) Big Mig r/c .061 engine and a RJL Diesel conversion head. Both are NIB at the moment.

Does anyone have any experience with this conversion? I am tempted so that I can run the Norvel at less than mosquito-noise-level rpm with decently-sized propellers. I'm curious as to whether this is a 'friendly' conversion or something that needs constant fussing over to keep working. I'm also concerned about connecting rod life.

I've run Cippola Diesels in the past, but not extensively, and nearby Old Flying Buddy has vast Diesel experience.

Many thanks.
Old 04-04-2003, 05:06 AM
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goldguy
 
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Default Norvel .061 Diesel Conversion?

Many moons ago when AME first came into the North American market, they were in fact diesels. The glow version came later.

I have used the combination you have, the RJL diesel conversion and the "older" AME with good success. I don't know if the rod is the same in both versions, so I would suggest that you break in the engine on glow, as you would if converting a Cox engine.
Old 04-04-2003, 05:49 AM
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PeterH
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Default Norvel diesel conversion

Frank, that sounds like I might have a possibility here. And seeing as already own the stuff, all the better. I had notions of peddling off the engine somewhere, but the Diesel conversion keeps it in sight. Any criticality to the number of head shims, suggestions about prop sizes? Any idea if the Norvel tank-mount is Diesel-fuel resistant? Is the original carburetor choke oversize for Diesel use?

Thanks again.
Old 04-04-2003, 03:06 PM
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AndyW
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Default Norvel .061 Diesel Conversion?

Peter,

I did a Novel conversion last year. I couldn't get it to run. This was a well run in engine,, on glow and it had adequate compression seal and ran well, and strongly, as a glow. However, as a diesel, the compression seal was inadequate and would only pop,, all day. However, I happened to have a few spare pistons and mixing and matching, found one that was an extremely tight fit. Normally you'd say it was TOO tight and not use it. But, I was determined to eliminate the possibility that compression was the problem.

I used a heat gun to free up the piston enough to get the engine started and limbered up as a glow. After that, the engine had that nice snap over feeling when flipped even after just shutting down. Compression seal was excellent. The result was an engine that would start, by hand, without the need to adjust the needle or compression screw. The first two or three prime runs would warm up the cylinder to the point where the engine would catch. Thereafter, a minute of burrp, burrp and it would transition into a nice growl and steady run. Throttling is virtually perfect, as good as glow. However, this engine has a bolt on muffler and an adjustable airbleed has been added. Prerequisites, to my mind, for good throttling. Also, this engine was the early AAN construction, NOT Revlite.

And, the round rod is not as strong as the one with the rectangular profile. Depending on how easy yours will be to start, keep that in mind if and when you're tempted to use an electric starter.

The tank has no fuel sensitive parts so you should be OK except for the line that goes to the throttle. Use black neoprene tubing. Head shims not an issue because you are adjusting compression with the head. A 7 X 3 should be ideal even with the barrel as is. If you go to a larger prop, the science dictates that you'll want to bush down the barrel. But, you never know till you try.

One last thing about throttling. If you're engine has three by-pass ports, you may not get good throttling no matter what you do. You need the engine with the five by-pass ports if throttling is a concern,, along with an adjustable airbleed.

All of the preceding is just my experience. Please don't let it discourage you. Unfortunately, I have a knack for doing that. Sorry if that's the case. Just try the thing and see what you get. If you run into problems, let me know and I'll try to help.

Having a diesel buddy nearby is a HUGE help. You'll see what I mean when you try to start the *%#@% thing. All our glow experience will hinder, not help.
Old 04-04-2003, 11:03 PM
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PeterH
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Default More experience....

Andy, that's a great collection of comments and advice.

The piston-seal experience suggests to me that running on glow enough to verify that the piston isn't squeaking to a halt at the top, and then going to the Diesel conversion, might be a valid choice. Especially since the operating temperatures of glow and Diesel (I think) vary so much from one to the other.

1I don't have the luxury of a pile of pistons and liners to mix and match, and I don't see that I want to. That alone makes the conversion to make a useless engine do some valid work seriously uneconomic. Run-what-ya-brung is fine, but there's limits.

And you're sure right about an experienced eye hanging around. That's how I got the little Diesel experience I have.
Old 04-05-2003, 04:30 AM
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AndyW
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Default Norvel .061 Diesel Conversion?

Peter,

In my enthusiasm to share my experience and to help, I may have inadvertently discouraged you. This is just my one and only experience. You MAY have an unusually well fit engine and manufacturing tolerances may have put the throttle spot on for your particular engine. Seeing as you have the engine, the head and diesel experience nearby, why not just give it a go? After all, Frank had better luck than I did and it could have been my relative lack of experience with diesel. I can guarantee that the experience will be informative and entertaining.

You can always convert back to glow.
Old 04-06-2003, 02:39 AM
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PeterH
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Default No worries

Andy,

You're very gracious to be concerned, thank you. I think I might have set off some misunderstanding. I didn't get discouraged by your comments. I'd noted your experimenting with pistons thought that perhaps I'd be better served trying to keep as sharp a piston seal as I could by running the engine 'just enough' on glow that it could be persuaded to fire after a toot from a heat gun on the cylinder. The idea being to let the engine seat itself at Diesel running temperatures as opposed to glow temps, all the while not trying to wear out the piston seal (in Diesel terms) by lengthy glow breakin runs.

This sounds like one of those experiments I'm going to have to do soon's the weather cooperates.
Old 04-07-2003, 01:50 PM
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AndyW
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Default Norvel .061 Diesel Conversion?

Peter,

Am glad to hear that you're going to give it a go. Good strategy to preserve compression seal as much as possible. I'd be very curious to know how you make out, RPM numbers, throttling etc.
Sometimes I get so wrapped up in my own results, I tend to get a bit too dogmatic. Need to hear other points of view and experiences to maintain perspective.

Good luck.

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