Are those FoMoCo rockers?

I am running the same cam in my 292 with flat top pistons.  I have stock 1957 "G" heads and rockers with stock valve springs and tubular push rods.  I set my valves at .018" hot and never had a problem.  It would take a lot of force to break those rockers.

a friends 56 sat for the winter and done the same thing.broke a rocker.no other damage and it didnt do it again.i didnt think they would break that easy.

Isky 301333 cam. .448 lift. They both appear to be exhaust valves. It's the 5th rocker from the rear on the passenger side and the 4th rocker from the rear on the driver side. The sour gas is certainly a possibility. The fuel in the tank is approximately 6 months old now, maybe a little bit older than that. 

The rocker arms are reasonably robust so they don’t break without a reason.  Can you identify exactly which rockers and pushrods (intake/exhaust) had the problems?  What kind of valve lift numbers are you running?  Assuming you have ruled out old or sour gasoline, a couple of things to look at would be valve spring coil bind or retainer to guide interference.

Lorena, Texas (South of Waco)

It would be interesting to see the two broken off pieces with adjusters as you found them just for comparison purposes. I wish you the best, like, hope nothing else is bent.


64F100 57FAIRLANE500

I said it was tinny, not tiny. It's been suggested that due to the vehicle not running for approximately 6 months now that it's possible the aging fuel caused a temporary valve sticking issue, which bent the pushrods. With the pushrods being a hardened chrome moly, could have caused the rocker arm breakage. 

Yikes!   That's not a tiny popping noise.  You most likely have bent valves and maybe a bad piston or two.  I doubt the rockers broke due to fatigue. Look for the guy with the size 20 shoe...  

So here's what I found when I removed the valve covers. Two broken rockers and 3 bent pushrods. Valves do not seem to be stuck. Rockers were on new shafts with plenty of oil getting to them. Is it possible that the arms just failed from years and years of use?

I'm going to start there and work my way out. I've watched The YBlockGuy's adjustment video about 5 times now.