The rest of the story
I was flying along at about 3500FT. (2500agl) at 2450 rpm when it let go. Immediate power drop and a lot of vibration (insert foul language here) I quickly went through the standard sick engine drill, mixture rich, fuel pump on, switched tanks, checked mags etc.... nothing doing no change. The closest airport was about 7miles off to my left, I headed that way and made a quick call on the UNICOM freq. about my problem requesting priority. The FBO responded with no know traffic. Engine was still make some power about 1800 rpm but the way it was shaking I was expecting parts to start coming through the cowl any second.
Made the airport no problem, flew a tight base, final, landed and rolled up in front the maintenance shop. They were standing out front wondering what all the banging was about!!
Great couple of guys, dropped what they were doing immediately started trying to sort out my problems. (a good mechanic can't resist tearing into a sick engine)
#1 definitely cooler than the rest so that gave us a good clue where to start. Getting ready to pull the jug, but when we valve cover came off close inspection revealed the spring problem. They had replacement springs in stock and in short order had them installed, compression checked all cylinders and inspected the engine. I ran it up and it was all good. I took off, circled the airport a time or two to make sure things were OK and flew home.
I feel very lucky this happened when and where it did. It would have been a pretty sketchy situation had the springs broken just after take off. I was also fortunate to land at an airport with such a accommodating maintenance shop.
The only real downside is that I'd just installed my new interior from DJ at Cleveland Tools. I think I might have bitten a hole in the seat!!!!