Anyone broken a rocker before on a 1600? (exhaust)
Just happened, snapped clean in half, bent pushrod on its first run around the block :(
any idea of the cause? incorrect timing? tappets not adjusted correctly?
anyhelp would be great.

Spanner,
 
Possibly the piston has come in contact with the valve.  If so, may also have bent the valve (is valve sitting the same height as the others).
 
Camshaft timing maybe retarded, if you installed a camshaft with more lift and duration timing is critical.
 
Bring the piston up to about 25mm from the top and look in spark plug hole and try and determine any marks on the piston under exhaust valve to confirm.
 
I would remove the head and if piston /valve contact has occurred, then check bigend bearing also. Check camshaft timing.
 
Goodluck
John

Have you had the head skimmed/ block decked? Might have to get push rods shortened, had it happen on a precrossflow- tappets sat up too high and gouged out the inside of the rocker cover!

Any more information, new built engine? Or new cam in engine? Or just an old engine? New rocker arm or 40 year old? So many variables / reasons.

I think i know what the problem was. I have a suspicion that it got spring bind as it has double valve springs.
Sorta makes sense as there is no way the piston can come that high on the exhaust stroke as the valve is closing at the same time. I have a set of single double strenth springs that i will throw in. Should be plenty for the street.
Engine was rebuilt a while ago and was run in a cortina until he sold it to the guy i bought the engine from.
The rockers look standard and have steel posts and spacers between the rockers. Ive decided to give it to a guy that knows what hes doing a give it the once over.

Interesting. I have doubles in my engine, and because the wires are , they don't bind as soon as single springs (with thicker wires) would.