detonation and valve to piston clearance

hey guys
I run a 451ci bae5 hemi, in a dragster, i have made a bunch of passes with this engine and never had any real problems, i had a detonation problem on the weekend caused bye excessive timing, hurt some bearings and threw 2 rods, when i disassembled the motor every valve has hit the piston in every cyl, i have never had any valves ever touch before, we turn the engine to 10300 but this is no different to any other run, i had new springs on the heads ( it threw the rods after 3 runs), i had the heads off after our first run and no valves had hit, nothing had changed except that it detonated, i understand that the cyl's that hurt bearings would touch because the piston would get closer to the head with all that extra clearance on the crank but not every rod bearing was damaged, after last meeting i went from a .040" gasket to a .060" so i have actually increased the clearance from what i usually run, cam timing is the same, there were no runs were it reved up quicky or anything like that i just cant see why the valves have hit all of a sudden, does detonation cause some kind of harmonic problem that stops the valve springs doing there job or is there another reason
any help much appreciated
aaron

 

yep every intake and exhaust valve, i havnt got the clearances in front of me and i cant remember, i wrote them down somewere, but they were ok when i checked them, the cam does have two dowell's the only thing i didnt check was to see if the cam gear has moved, i will check this on monday when im back at the shop, only 4 of the rods hurt the upper and lower bearings not all of them, the other 4 were fine

 

You say you had new rods in it, we have sometimes run into the problem of getting the wrong length of rods from what we ordered. Did you check the length of them in comparison to the rods you took out? If you were close to begin with, then even a small amount longer rod might cause some issues. Just something simple to check.