Hi,first time here: Sorry if this is common knowledge, but I could use some advice. My old stock 49 chev 1 ton has always run great when I've needed it too. I only use it rarely, for hauling firewood a few times a year.I have owned it for 25 years, or more.It never miss's a beat. I started it up the other day,and it knocked like never B4, then wouldn't start again. Long story short, I removed the valve cover, and push rod cover, and found 3 bent push rods, and 3 stuck valves. I freed up the valves with WD40, replaced the bent rods,and put it back together.It ran great for a good 1/2 hour.Thought it was fixed. Next day,I tried to start it again and the same thing happened, only this time it was 5 bent push rods, 5 intake valves where siezed up. Very Unhappy. The exhaust is rusted out, and I have been using unleaded gas forever.It has clean oil. Any Ideas..? Thanks,