I can't figure it out, maybe you can?

Broke two rocker arms on my 1973 Dart Sport 340 bracket car.
Pulled the heads and replaced the valve springs, hyd lifters, rocker arms.
Went out and it wouldn't rev past 5200 rpm.
I replaced the orange spark box with a chrome one and went out last night.
Better, but still won't rev past 5500 rpm. "



How did the pushrods look? Which rockers are you running?

Sure the springs are rated for the cam?


Strange you broke 2 rockers with a Hyd cam....... are they clearing the retainers?


I would look at the timing chain / gears , also and verify everything is good at TDC.

my old Orange box went to 6200 all day long--i doubt its the ignition---

just throwing some ideas out there...


try a leakdown test for the valves

??