Ford 2000 OHC /advice/help

wanting more,we decided to modify our 2000 OHC, kent high lift cam,double valve springs,twin webers,48 IDFs,took a while got it chassis dynoed running great,from about 3500-7000--
to the track one lap and it all went to s*** . Thought we had a broken valve spring or the belt jumped,took off the cover today and found the locking nut on the connecting rod bolts on 4 of the valves had shaken loose had about 3/16' gap between rocker arm and cam.
Anybody had this before? Ideas,sugestions on how to lock the locking nut,I know on the 1600 they have undercut nuts so they dont move on the threads.

thanks John

They dont use a lock nut. You just need to make them tighter.

You are not alone having rocker stud lock nuts come loose .CAUSE. the mating face of the locknut is not at right angles to the thread so no matter how much you tighten it you only bugger the thread further the locknut seems too thin ie not enough thread being really only a half nut . I had one come loose on a brand new alloy head,the nuts come loose and the stud wound itself in. The rocker jumped off the stud wrecking the whole engine. to correct the problem I have made new nuts similar to a K nut in shape with a larger mating. surface and 4 more threads, better material, and with a mating face square to the thread. I would be happy to supply you a drawing or we can make you a set if you can supply me an E mail . sloanedogon@xtra.co.nz