I just picked up a Bluebird N.S. 51 from eBaaaaaaa at a very good price but imagine my surprise when it arrived and turned out to be absolutely brand new! I took off the backplate and found two pieces of swarf about the size of dust but flushed it out anyway. There was however a LOT of swarf between the carb and housing. But the moment I realised it was new I decided to use it to find out once and for all what happens to an ABC if it's run in rich (see above about "very good price"...read "cheap"). We all know the horror stories...it'll be junked...the rod will fall to pieces...etc etc. I've never totally believed in that but I've only ever run in one ABC and that was too valuable to go experimenting with.

So onto the test stand with it. Now one thing I go along with is using a smaller than normal prop so I found a 9x6 wood. Fill the 8 ounce tank with fuel (zero nitro, 24% oil with 1/3rd being castor), give it a bit of prime and in one flick it was running. Nice. But so rich it couldn't keep running so close the needle a little. Another flick and it's running again. It sat there in a solid 4 stroke turning 11.7K with a head temp of 175F. I let it run for about 2 minutes then pulled the fuel line off...let it cool then restart (one flick again). I did 3 runs like this on the first tank and called it quits for the day (I think my neighbour was getting irritated ).

The pinch still felt exactly the same as before I ran it, meaning that you could feel the piston start to tighten up when the prop got to the same position as before so I removed the muffler to check the piston. There wasn't a mark on it (even using a magnifying glass), nothing to indicate that the top portion below the crown had been subjected to any torture whatsoever.

Today I ran two more tanks through it (at 3 runs per tank as before) but this time I went even richer. The first tank it ran at 10.3 K with a head temp of 160F then the second tank at 8.7K and a temp of 145F. Total time so far is a bit over 18 minutes. Once again I took off the muffler and used the magnifying glass on the piston. It still looks brand new. No signs of scuffing near the crown, the pinch still starts in the same position.

As for the rod wearing out, there's no signs of that either. The way I check is to slowly turn the prop until the piston is tight enough to lock in place then see how much movement there is at the prop tip. Any movement is the combined clearances of both ends of the rod plus any piston boss clearance. It's unchanged from new.

It's early days yet and I intend putting several more tank fulls through it before I even consider letting it 2 stroke but so far I'd have to say that not only has it not destroyed itself but I'd go so far as to say it doesn't even appear to be running in. Mythbusters anyone???