my 408 build

racerbob said

I bought the cam with the complete Comp cams kit (K-231-4) and found out they include valve springs that require a higher installed height than what is available with stock mopar valves in the J heads. Comp Cams 986 springs came with kit have an installed height 1.75" , stock heads are good for 1.65" or so. Sort of Pissed me off, that they sell a cam kit for a mopar engine with the wrong springs in it!!

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They sold the right springs to you...lol You just ran stock length valves...lol. It's common to cut the spring seats down, or use .110" longer valves, or a combination of those with tall retainers to get the required installed hieght. I always consider it a mild risk not using what the manufacturer spec'd, but, going slightly heavier should not hurt it so long as you break it in properly (without the inners) and use a good oil. These will definately be able to run way into the 12s in a street A body with these setups and properly matched drvielines.