Dan,

I've had my Norvel .074 dieselized for several years now and did it similar to AJ's. Andrew has a better idea though with the locking bar. My first contra piston was very tight (by way of the O-ring) and needed nothing to hold it in place. However, as the ring wore in (or out) the contra tended to drift. So, I installed a heavy spring and that seemed to cure the problem. Till lately. I'll be adding the locking lever soon.

Regarding performance. This depends greatly on the prop. See the thread at http://wwwrcuinverse.com/forum/m_247..._2/key_/tm.htm

As you'll see, the 8 X 4 Cox grey did best on the ground (at 12K) and in the air. The APC was the worst.

My fuel is home brew, 40x40x20x2. The oil was Sig castor.

Martin (DieselDan) had consulted me privately with his starting problems and my advice was to use a 1/2A starter with the caution that the stock rod was going to be in jeopardy if he wasn't careful. In the end, Martin got his going by hand. Mine would start by hand occasionally but only if it was gummed up with lots of oil and only on the first start of the day.

The trick is to find the compression setting with no fuel in the tank. Then, only two or three drops of prime into the intake is sufficient to fire off the engine with a starter. Quite often the .074 will start with no prime required. I just fill the tank and apply the starter. After 10 to 15 seconds, enough fumes are drawn up the fuel line to fire off the engine, and it keeps running.

As a matter of course, for my dieselized Norvels and BECAUSE I use a starter, and ONLY because, I routinely make up a beefier rod. Also pictured and posted earlier are my first ideas as to dieselizing the .074. Concerned that the crank was going to break, I installed a Cox .09 crank. Power was way down and this turned out to be a failed experiment. Note the rod. This was overkill and the rods, lately, have been trimmed down a bit.

However, I've been running the same stock crank for nearly three years with many, many tanks of fuel through it and that crank just keeps on taking a licking. And it hasn't been babied, it's been whacked with a starter many times.

Also pictured is a dieselized Norvel .061 done up in a similar fashion. My first attempts at dieselizing Norvels were with the original AAN engines and what it took was a mixing and matching of components to get a super tight fit at TDC. This was then VERY carefully run in on glow. As a diesel, all it took was two to three drops of prime and it would fire off, by hand, after two or three tries. NO adjustment was needed to be made to the contra piston to start. What would happen was that each prime run would bring the cylinder up to near proper temperature until at one point, it would keep running with a neat, burrp, burrp sound. Then it would smooth out into a solid run. At the time, I happened to use a Wasp crank for the experiment and eventually the crank broke when I went to an 8 X 4 prop, just to see what would happen. I concluded that an 8 X 4 was just way too much load and never did it again. Till recently that is. I've run the Norvel .061 with all its proper pieces, including the crank and had a good full tank run with nary a blip on the crank. So far. For some reason, on the 8 X 4 prop, some days it'll run, some days it won't. I've got a video clip I can send you if you're interested. RPM was 8K plus on that day on my mix. It was surging a bit, don't know why, still working on it.

The upshot of all of that is that the Norvel cranks are TOUGH. Not to worry about them when dieselized. Norvel got it EXACTLY right in this area and I, for one, am grateful.

Just for the interest of all, there's another way to avoid having to cut metric threads when dieselizing a Norvel. This involves making a complete new head. The entire head is simply bolted in place with much longer screws. Pictured is the one I did for my Norvel .15. Like the smaller ones, the Norvel .15 dieselizes just great. Starts easily with a starter without having to touch the compression. Again, this is with my 40/40 mix. Lots of ether really helps.

For anyone interested, I've got a 15 minute video of the starting procedure I use and some flying of my sport design. This was taken last year. I've also got one flying off of skis using the ski design I published in Flying Models a few years ago. Dieselized Norvels are just incredible. With the starter, no problems starting in the winter, again, without ever having to touch the compression screw. It's always very close for starting and only the occasional tweaking is needed to suit the weather of the day.

The beauty of a dieselized Norvel is that you can break it in as glow and even find the needle setting on glow fuel. It'll be very close to that required as a diesel. Saves a LOT of hassle and wear and tear on the engine AND you.

Finally, it must be said that just as with glow, the dieselized Norvel .074 throttles virtually perfectly, right out of the box. As in the glow version, it must be kept in mind that the high speed needle has a broad range and is actually used to dial in the low speed. Keep tweaking in the high speed needle (at idle) till it holds on advancement and no more, and that'll be about perfect. I generally do additional tweaking while test flying.