Ed, the rod doesn't seem to be manufactured any cheaper than the old rods that were bushed top and bottom. Even though the ends are larger, they kept the crank end bushed.

I quit work early today (shouldn't have!) and put it back together... Earlier I forgot to note the rocker arms are beefier in almost every dimension, did not get a chance to see if they would be a straight swap if someone wanted to upgrade, but they do look like real nice units without being too heavy.

Also when putting it all back together today I noticed that the piston ring is really stiff, didn't notice if it was any taller or deeper than normal, but right away it was very obvious how stiff it was.

You know, I get the impression with the bigger rod ends, stiffer springs, stout rocker arms etc. that O.S. has built an engine relating to how we are running them these days... the trend is to use low pitch props and high rpm for 3D type flying. Nice to see a manufacturer realize how the consumer is beating on their products! I think those changes are great, now let me tell you how it ran...

I used the same fuel blend as Hobbsy, and ran three 16 ounce tanks. Had a Zinger 12x6-10 for the first tank and a half then an APC 12.5x6 just to keep the load light. Kept the RPM below 7,000 for the first two tanks. Was able to get the idle down to 1,800-1,900. I really like the muffler, the adjustability is great, and might even be used with the old style 15 degree header if needed for more options in installation. You might want to keep a few of the o-rings as spares, or if you pull the baffle out just remove it entirely and smear some high temp permatex in it's place.

After the first tank and a half I pulled the valve cover off to check the valves, the intake only needed a tiny adjustment. What I was really interested in was how much oil was in there! The new lube path seemed to be doing it's job very very well. It's obvious that the cam, and followers get a lot of oil as it travels past and then up the pushrod tubes. I blew all the excess oil out of the head then put the cover on and ran it again for two minutes, pulled the cover and it was drenched again. It was impressive. Never seen that much oil in the top of a head before, not even in my ys-63s. (It has 4 holes around the intake valve guide)

Now here's what I didn't expect, I slowly started leaning things out a bit and playing with the throttle, at times it was running really well, but mostly I wasn't happy at all. So I kept tuning and playing and things got better, but worse at the same time. Idle was awesome for having such little time on it, but the midrange was pure crap, very rough and smokey. The top end was knocking and detonating like crazy so I richened it up and it blubbers, lean it out anything less than blubbery and it pings like mad again.

It was time for me to stop for the day, but as I was cleaning up I decided to try a quick compression test... 105 psi!!!! My jaw dropped, I said a few words that made my son gasp and I cranked on it again, yup, it was 105 psi. Normally everything I have runs from 60 to 75, sometimes 80, the exception being my FA-60t (I have three!) which always gets 40 psi no matter what I've done to it.

So my powers of deduction went to work again and this is what I came up with, let me know if I'm going in the right direction here... I've been reading for some months about piston ring design and function as well as how to make them. If a ring doesn't provide a good seal yes compression will be low no matter what the combustion chamber volume is (too much blow-by), but a good seal is also needed to provide ample vacuum to suck in the next intake charge, the better the seal then more vacuum is created, that's a good thing.

Just a few of the factors of an efficient ring design are...

1. The pressure the ring exerts on the cylinder wall, must be high and equal around the bore, but too high creates too much friction and that means too much heat, more heat means expansion of the material. Drastic examples of expansion would be end gap closing and touching, or ring thickness expanding and taking up all the clearance in the ring groove.

2. Clearance in the ring groove on top and bottom as well as the depth of the ring in the groove.

3. It's actually a good thing to have pressure go back across the top of the ring towards the bottom of the ring groove and get behind the ring during compression, and the theory is less leaks around that last corner at the bottom of the ring groove. That's what I've been reading but don't know how to explain very well.

I'm guessing the stiffness of the alpha ring is creating all this compression, it surely isn't the end gap, that measured somewhere between .007" and .008" which is huge for such a small bore. All that oil up in the head all over the rockers and an 1/8th of an inch deep in the "galley" means plenty of oil is blowing past the end gap. Maybe O.S. found that they needed high ring to cylinder wall pressure to create a larger vacuum in order to suck in the fresh intake charge as well as the oil returning from prior blow-by. I could be completely wrong about all this, would like to hear what you all think. If someone else out there has an alpha let us know what you experience!

I don't have any lower nitro fuel than 15% on hand to see if it runs better/smoother. Maybe if I can find the time in the next week or so I'll make up a thicker head gasket and try that, wouldn't that prove if my thinking is right or not? Maybe it's my thinking that is over compressed! hehe

Could it be early on in the production run that the ring just happened to turn out this way? My experience in trying to make my own rings has been a futile one, the tolerances, the heat treating/annealing, gap... it's crazy.

I've read elsewhere on this site that some think 100% recirculation of oil could be cause for pre-mature wear in the engine, after seeing how it works in the alpha, I tend to think if there is a problem in an engine creating alot of metal, that's a bigger problem than any lube path type could ever fix. If that's the case, any engine won't last long enough to worry about any recirculation of material through out the engine.

So for now dear Hobbs the only # I have for you is 9400 with that 12.5x6 knocking and rocking the whole time, it peaked at 9650. I'll have more later!