Yep matching springs with cam change. I checked timing at the track. 18 initial 34 total. I did use a new dial back light. Going to double check with my old light to make sure it reads the same
Could it be that the "matching springs" were not set at the recommended installed height? like using longer valves than stock(gm .100 longer valves) and spring install height was designed for standard height?
Valve starts to float, top rpm lost, slower mph.