tonight (this morning?) at 3am i was making the 15 mile trek home from work in the Nova, and kind of got on it a little bit at a stop sign- no big deal, tach never saw the high side of 4000 rpm. get up to cruising speed around 60 mph, and all of a sudden the car kind of starts running crappy and making an awful thunk thunk thunk sound. first thought- "****E , i blew it up!!" pull over, and it idles really rough, and all of a sudden the noise stops and the idle smoothes out. nothing seems wrong, figured it was the Gods playing mind games with me in the middle of nowhere, and i leave. it kind of misses under load, but no big deal for the 6 miles to my house. good oil pressure and temp stayed at 185 like always, and no knocking noises. get it in the shop and run a compression test- 180-195 on every cylinder but #1, which was zero. pull that valve cover off and see the #1 exhaust rocker kind of sitting on the stud, and no pushrods in sight on either intake or exhaust on that cylinder. pull the intake, and the intake pushrod is laying under the roller lifter "spider" thing in a nice lightning bolt shape, and the exhaust pushrod is kind of sticking up thru the hole a litle bit and still straight to the naked eye.
my theory- the exhaust rocker poly lock let loose, and the nut spun off (intake poly lock was still tight, but the pushrod was all mangled in the valley). the exhaust pushrod went flying and took out the intake pushrod and sent it into the valley- that was the noise- a pushrod getting banged around and screwed up. damage is minimal- 2 pushrods and rockers, and a new set of intake gaskets. about $100 thru my GM connection, i think. could have been MUCH worse- could have trashed my $3500 engine (after only 3 years and about 30,000 miles) and i could have had to walk home...
i took pics of the carnage, but need to upload them to my webshots page yet. maybe around noonish or so after i get some sleep.

Sorry to hear of the trouble. I know it was probably the last thing you wanted to see/hear at 4 AM. Sticking valve? Weak valve spring?

Sorry to hear about your misfortune. Sounds to me like a broken lifter or valve spring may have started the whole mess.

Good luck . . .

it was the exhaust rocker arm that came loose- the poly lock didn't hold for some reason. i came to this conclusion when i went to wiggle the rocker arm and it lifter right off the stud- the nut was sitting on top of it and looked like it was screwed down, but it wasn't. ordered new rocker arms and pushrods, but have to wait til wednesday or so to get them. no dealers withing 1000 miles stock single 1.6 LT4 style roller rocker arms. my local dealer ordered from Pace Chev. $100 fix- but it could have been worse.