My 481x Dropped a Valve?

every thing in the head was New less then 15 passes. never over reved it. made a pass it had some smoke about 500ft checked the valve's and every thing seemed fine. did the burn out then it smoked like a train? got a single other guy broke after the burn out hit the 2 step white smoke pored out then 700ft you couldnt even see the top end. pulled the heads today No Piston left Cracked the block and Main cap. what do you think made it do it. we only spin it to 8900

 

Do you think the piston broke first? How many runs where on the pistons. Have the heads been serviced since put together. I take my 481X heads apart ever 2-4 runs and check everything.

 

pistons 15 runs. heads 15 runs. we never pull the heads intill rod change but they only had 15 runs. we check are valve's every run

 

2-4 races are runs?

 

What kind of springs,retainers,locks what spring pressure did the head break or stem. i am building a set of heads now got the pac duel springs 525# on seat ,super 7 recessed retainers and bead loc Ti locks that AJ sells

 

How do you monitor spring pressure just pulling the heads when you change rods. At what rpm are you shifting. What springs and retainers.

 

I have see over the years several..valve tips to like shear off

 

Mine dropped a new-zero run Stealth valve during a warmup, new springs valves.
Was a non beadlock, broke at the groove. Went to the locks and never had another failure.