Possible cam install

What comp cams is referring to is the clearance needed for the spring to work.They are giving you the minimum clearance at full compression.
To use the old valve springs over, you have to check them for strenth first with a spring tester.
Valve springs wear out unevenly and have to be checked ,and then set up on the heads with valve spring shims.You need so much installed height for the correct spring presures.
BUY NEW SPRINGS AND THIS IS WHY!!!!!
New valve springs are tested for strenth and put into a matched set.
This keeps all the valves on the engine at a even amount of closed presure,creating a more even amount of power per cylinder.
Also you want to know your valves won't float at high rpm ,due to old valve springs that where ment for a differant cam.
Thats like running a old set of rings in a new motor cause they worked before.
Rings and valves are what seals the motor.
It could kill your power during higher rpm use and also kill your motor by floating a valve.
They are one of the cheapest parts to replace,so why take a chance.
The motor will make better power and be ok during high rpm use.
GOOD LUCK :-\"