Varying compression numbers, same cyl

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Finally got it all up and running. Took it for a water test, idled out of wake about 45seconds....Ran it for about 45 seconds....saw the warning light, let off throttle, heard the horn, and engine stalled as I let off throttle. No starting again.

Try to start the engine with plugs in, and it will turn over maybe 1 or 2 cylinders, then stop (can hear bendix freespinning). Take all the plugs out and engine turns over strong.

Put a compression tester on it, and I hit 150 right off the bat on cylinders, except number 2 was a bit lower at 100/125 (forget). I could keep cranking it over a little and got at least 1 and 3 to 180ish. I had trouble getting the starter to continously engage on 2 cylinder with comp test in.

After I took a compression on each cylinder I went to double check. My numbers were vastly different. Sometimes I would just get like 50-75 and that was all. Sometimes I would get 150, then the next one 75.

Pretty soon I noticed that anytime I did a cylinder, I would get like 150, then 75, then 50, then as low as 20. With the starter engaging.

I was not cranking on them long, maybe 2-3 seconds each time. I've done plenty of compression test. I also check battery voltage and it was 12.8-13.1 (had a charger on it) at the starter relay going to starter. I felt the starter and it was NOT hot. It has a brand new battery and even brand new battery cables.

Any ideas?
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After thinking about it...The only thing that can cause various compression like that, is the camshaft. Pulled the valve cover and found the timing chain was broken.

Is this a common issue?
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Im starting to guess that I didn't actually overheat the engine. I think it just had enough time to snap the timing chain and then the alarm was the cam gear being out of timing.

I'm guessing there's a decent chance I didn't bend valves since the camshaft gear was not moving with the engine, so most of the valves probably just closed.
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