Your pushrods are not strong enough. Any time you can’t keep the adjuster tight the first thing I look at is the pushrods. IMO they need to be at a minimum 7/16-3/8 single taper. 3/8-7/16 double taper would be even better.
Norris rockers have the same oil hole clocking that Chrysler uses. That means the adjuster needs to be 9/32 out (thats ~.287) plus .050 minus zero. You don’t have much room and to do it right the intake pushrods need to be .050-.060 longer than the exhaust pushrods because of the offset.
Every pushrod manufacturer in the country will tell you their 3/8 thick wall dong beater pushrod is more than good enough and they are all wrong.