If stock LT1 springs are installed at 1.78", and Cranes 10308-1 springs are installed at 1.875", where does the extra height get assimilated? Do I need to get longer valves (and pushrods and valve covers), or does the head get machined for deeper spring seats, or what? I'm planning on putting the Crane springs on Lt1 heads if it isn't going to be too much work/cost.

 

You could use a retainer that gives you the .100 increase in installed height. That some times reduces rocker to retainer clearence.

 

The retainers in the 10308-1 kit give you more installed height.

 

AH ok...I'm still learning the valvetrain geometry stuff, thanks alot guys