Little history, 1976 CJ-5 with a 304. The vehicle had sat for about 10 years before it was given to me. I found it had a bent push rod when I fired it up in #3 cyl. Replaced, now ran good. Jeep sat idle for another 2 years while I upgraded the running gear and other stuff. I took it out on it's maiden voyage last Saturday to run in the new gears. Ran it up and down a long gravel hill for about 30 mins. just to warm up the diffs. Took it home to park it. It ran beautifully all during this time.
Tonight (two days later) I fired it up again and it ran awful. Narrowed down to a cylinder, found bent push rod.(#4 intake). Checked the rest on that bank, also found #8 intake bent. I checked to see that the valves were free by bumping with the butt of a 3 lb sludge. I could feel good spring rebound so I'm assuming they are free. I don't know if the P/O changed a cam or springs. I didn't see anything obvious that performance work had been done. Because it was running perfectly when I shut it off on Saturday I'm assuming this happen when I again restarted it tonight. If anyone has any clues as to what might be going on I'd be anxious to hear.