.... stock L92 or LS3 style head casting? I'm wanting to put a 1.550 dia. roller spring on a stock casting but don't know how thick/thin the casting is at the port roof. The idea was to use a shim stack of about .040 on the stock spring seat and then to cut for the big spring and then use a locator (about .060 thick) under the spring. Then use a +.100-length valve and use a spring set up at the stock height of 1.800in. The math says it should work but I don't want to cut through the port roof, and I don't have a junk head to experiment on.

If this would work on a stock casting, then what about on a CNC ported casting? One from GMPP or SDPC is what I had in mind. Thanks.

 

Stock head will need to be cut for sure

Since they accept a 1.300 diameter

Most aftermarket heads have the bigger spring pocket.

 

Pac has a 1.3 diameter spring that will work with the stock valves and 1.8 installed height. Might be a better option. Pac-1335