I have a SBC 400 engine with Edelbrock RPM Aluminum heads,Comp Cams Hyd cam(.469" lift),Comp Cams 1.6 Magnum roller rockers with polylocks,about every 4-6 months a couple of rocker arms will come loose and I will have to readjust them,I get 0 lash on them and tighten to about a quarter turn after 0 lash,do I need to tighten them to about half a turn or what,ANY HELP?THANKS