Steve and I ran some of our diesels on the weekend, with mostly good results bar one engine.

I managed to get 3 cans of JD quickstart from the local John Deere dealer, so did the "invert the can and spray the propellant out" thing. Made up about 800ml of 45% kero / 30% ether / 25% castor fuel.

First engine on was Steve's Oliver Tiger replica (not a CS). The first run was ragged, possibly due to some remaining propane propellant in the ether. We let the fuel bottle vent for a bit and later runs were fine. With the fuel settled down the Olly clone settled down to a solid 11,600-11,800 on APC 9x4, with 12,000 obtained by fiddling further with the needle & compression. The next time we run his Olly it'll be in a plane.

Next engine up was my original PAW 19DS that I've owned since 1981. This was a disaster. More on that - see below.

We then went to a PAW 19DS-3 that I bought on eBay. Easy starting & adjustment, turned a Master Airscrew 9x6 at about 9,200. I had doubts about the merits of the Master Airscrew, and expected more thrust, so tried a Bolly Clubman 9.5x6. Much better - 9,600-9,700, a happier sounding engine, and more thrust than with the master airscrew. The Bolly 9.5x6 is a really good match for the PAW 19, and will be the first prop I try for flying when I get it into a plane.

The final engine we ran was my NIB early serial number MARZ 2.5D. Taipan 9x4 prop. Initial starting was challenging, as it turned out we had the compression in a turn too far. Steve was able to get it to a start, and we gave it a nice rich under compressed run, then peaked it for the last minute or so. It responded beautifully with a lovely smooth powerful run, lots of thrust, and sounded like it was doing just under 11,000 (it was too dark for my tacho to work). Not quite as strong as the Olly, but I think it'll get within 500 rpm when fully broken in. It was definitely still improving. After running it felt very much different to before - much smoother bearings and superb compression that does not leak away at all. I'm quite impressed with the MARZ for such a cheap Soviet era engine - its easily as powerful as a PAW 15, and will do nicely for sports flying in some kind of profile stunter. It was a good thing that I opened & cleaned it before running though - there were quite a few metal filings inside the crankcase.

Now, to my original PAW 19DS that I mentioned before. After mounting & priming we were on the verge of getting it to run (a few pops) when there was an almighty crack and the tommy bar popped out a millimetre or so and would not screw back in. When I took it out I found that the thread in the cylinder head had neatly shelled itself into a helical coil around the thread of the compression screw. I'm just glad that a PAW 19 head is an easy item to replace. I'm a bit bummed out about it because this particular engine was my original "big" engine and the only one that I have a sentimental attachment to. Steve's taking it back to Wollongong with him to hand on to David Owen for evaluation.

cheers,
Colin