After posting on various threads enquiries about Aurora engines, I thought I would start one of my own.

The reason is - today the postman delivered an Aurora K 600 BB R/C (.35 cu). A sardonic joke at my own expense perhaps?

A week ago I went onto Carlson Engine Imports site and ordered a K 650. Mr Carlson emailed me back and politely said unfortunately he was out of stock. A K 600 R/C was offered in substitution. As it was on special ($90-) I accepted.

I will not post pics of the engine here. My digital camera is of poor quality. Here is a link to images of the K 500. By clicking on "baja" the images will be blown up. The K 600 engine looks essentially similar to the K 500 in all respects. Cosmetically, the engine I have differs ... for the better in my opinion.

http://www.rojobcn.com/technic/avion/aurorak500.htm

I will report my findings over a period of time, ending up with a bench report when carrying out running in. I have no aircraft to put it in at the moment.

Initial Impressions:

The engine is delivered in a stout, well made plain white box. The cardboard is thick and of a strength that has not seen for packaging of mainstream engines in decades.

Inside, the engine sits in an inner protective casing of cushioning polystyrene pieces. The engine itself is packed in a ziplock plastic bag. Padding in the form of crumpled paper that looks like old fashioned butcher's paper is used to ensure the contents as packed cannot move about.

Instructions are "quaint" and are printed on a folded sheet of A4 gloss buff paper, in a type set reminiscent of the 1940's. The english is a little convoluted but far, far better in grammar and syntax than many far eastern instructions.

As one would expect from a pukka manufacturer in a former British colony. Pip pip!

Prop and fuel recommendations (olde english brew of course!) are given, no surprises with the recommendations, however there is no schematic or parts list.

The engine is assembled with an R/C carb attached, but the main needle is seperate and is to be installed. You screw it on

Things that I notice that really stand out:

1. The all metal carb is finished in satin black, which is very nicely done .. very similar to a black metal bodied Irvine carb.

2. The cooling fins are nicely finished in satin black, looks good though a little sparse in application in places.

3. The head is separate, and is bolted on by three short slot head bolts. It seems to be turned from solid and is finished in a high grade gold anodise. Looks very attractive, and matches well with ...

4. The included round base spinner nut and prop washer, both of which are gold anodised, and finely finished. The spinner is of a pleasing contour. It's not unlike the items Du-Bro sell but not quite as pointy, and its diameter matches that of the prop driver, which appears to be well turned; free of any marks, and which sits on a split collet. A standard prop nut is included as an alternative to the spinner. A tommy bar is also included for tightening the spinner up. Very thoughtful.

5. Nice fine finished aluminium screw-in backplate, a-la PAW again, with milled slots for removal / refitting. "India" is stamped in the recess ... the only identification on the engine. A fibre gasket seals it where the flange meets the back of the crankcase.

Case Casting

The block is unitary construction. The finish is of a rough dull grey bead blast. The cylinder is that ... cylindrical. Die marks are clean with no evidence of hand filing to finish. There are no pock marks or signs of slumping in the alloy. There are a couple of minor nicks on the outer surface of the mounting lugs, however these are not at all deep and I suspect relate to "mounting" at the factory for assembly purposes. Oddly, there are no serial numbers anywhere, or any marking noting the name of the manufacturer or model/ displacement. PAW - like in that regard. Some waxy residue has stained it in places.

The exhaust collector is a clamp-on ring device, again quite PAW like, with a stubby muffler attached pointing away from the head. This has an internal baffle of the "pepper pot" style (like the holes in a colander) through which exhaust gases eventually exit. A short stinger finishes it off, to which a diverter or coupler could be attached, if so desired. The muffler is angled at 45 degrees from the crankshaft, on the usual side. There is no pressure nipple. None would be required.

The carb appears to be held in place by an English Irvine / PAW type of set - up. That is, two grub screws holding the inlet shank. Commendably, the bosses are thick, and are raised proud of the inlet, so there is plenty of "meat" for the threads of the securing screws.

Here is when we see what to me is poor looking hardware ... two slot head screws, one of which has the head very chewed up by the screwdriver used to set it home. I have not yet backed these out.

Carb

Nice looking black rectangular solid metal unit, of the fuel metering twin needle type. Main needle is finely tapered and the needle body is held by a firm and effective ratchet clip, it looks PAW like except for the knurling on the body that interacts with the spring clip to hold the setting. It screws a long way over the inlet needle ... nice, there are no "O" rings to wear and leak here! The inlet nipple is hand made and silver soldered onto the main needle. Frankly, it looks agricultural but is nicely done and the solder is smooth. it just looks ... hand made?

Idle needle screws into the Carb from the other side and is easily accessable as it is well proud of the carb, held under firm tension by a well made spring. This idle screw will not wander! I like it. A barrel retaining screw, also under spring tension, holds the barrel in place and sits on top of the carb, angled slightly backwards. The angled groove for the barrel is well ground, no burrs. Barrel is tensioned by a wide circular spring which sits in the carb body on the inlet side and pushes the barrel up nicely against the retaining screw ... so tha barrel will not move side-to side. Why do PAW not make twin needle carbs like this?
The fit of barrel to body is adequate ... like most engines. Choke diameter is about 5 mm. I did not measure it.

Throttle arm, as delivered, is steel and is on the upper side of Carb (?) ... Why? so, I remove the idle needle and spring, release the securing nut, and I turn it round to the more usual position. I nip it up (using a 5/26" hex socket), replace idle needle and spring ... all good!

Carb is sealed to the intake by the usual black "O" ring. It is firmly compressed, so air leaks are unlikely.

OVERALL IMPRESSION .... NOT TOO BAD at all!

Don't like the prop washer for use with the prop nut though, its just an anodised flat washer - for use only with the spinner. Being flat, if you use the nut, please use a contoured proper prop washer, preferably steel, though alloy would do. I will find one in my box of bits for use with the prop nut.

OK, now for the bad (?) news!

Problem / Challenge

1. The carb barrel is locked solid .. I cannot move it with the throttle arm. Hmmm ... think

* Apply spray oil (WD 40) liberally into carb. Wait 2 hours.

* Not budge .. so I remove idle needle, spring, nut, throttle lever.

* replace nut, screw all the way down on to barrel

* remove barrel retaining screw and spring on top of Carb

And keep turning the screw with the socket drive ... as it hit the bottom of the thread, finally, the barrel slowly gives up and gradually moves! It was held fast by congealed preservative that has hardened to a dark brown tar like substance. I spin the barrel a few times and pull it out of the carb body, a few sprays of WD 40 and some wiping and the gum is gone, reassemble carb, and it moves smoothly once I adjust the barrel retaining screw. Phew! the gamble paid off!

2. The crankshaft is locked solid! Won't turn! Don't panic, it is no doubt a victim of the gummed up preservative again. I place a prop on it (usual 1/4 diameter fitting) (11x6 Graupner), nip up the spinner and try to turn it over ... no luck! Still locked solid. I will soak the engine in petrol for a few days to get it to loosen up. Prop tips move 2~3 mm ... ok.

I will report back further once the engine has had a soak.

I may remove the backplate and inspect inside the case ... if only to remove the gummed up preservative [>:] ... Once I get the thing turning!

I have to say, the bling factor on this engine is superb ... if you like that sort of thing .... similar to a Saito gold knight ... the gold head and spinner really sets off the black carb and fins !!!