Katech Mike - very helpful - appreciate the post. We will install the valves as is into the LT1 heads knowing we have 30K miles on them already (likely a bit more clearance than when new!).
Adding more detail on the LT4 intake valves - starting with OEM LT1 valve weight:
New OEM LT4 Ti valves:
Even though the LT1 valves are carboned - at least a 20 gram drop in weight which is impressive!
My next question is the valves spring height. The OEM LT4 intake valve lock groove is ~.200 lower than the LT1 valve. So all else equal, the spring pressure is much higher. For the 1516 springs at 409 pounds an inch = 82# increase. Seems excessive. It appears the OEM LT4 retainers are same for intake and exhaust. Likely I'm doing something wrong...
Comments?