Totally Dissapointed!!!!!

Breaking in an engine beyond the first few minutes is mostly ring seating. If moly (faced) rings are used, and the bores are finished correctly, this is nearly instant, but can take up to a couple hundred miles. Lycoming and Continental advise high power first flights for new cylinders on aircraft engines. We baby ours, go figure.

Now, repeat after me: "Clearances never wear in, they only wear out." Right up there with "Measure twice and cut once." And in engine building, they are related. Heres the point I am driving at; if the top ring gap wasn't sufficient, they could have gone solid and either fluttered or broke. Not good. Al leakdown will show this.

So, what is a leakdown and how is it done? The cylinder is placed at TDC (usually), the crank locked in position, and compressed air applied. Next the air is switched off and the rate of leakdown is measured over a fixed period of time. Drop in pressure divided by the original pressure gives you a leakdown percent. Even better, you can generally hear where the air is leaking (crankcase, intake or exhaust port). This test is a really good indicator of engine health (as far as power potential goes) and that is why airplane engine compression checks are done this way. Besides recruiting your friendly neighborhood A&P, any "performance" machine shop should have this capability. Also, leakdown testers are available through Racer Wholesale, Summit and the other usual suspects, but not super cheap.