Inliners International Forums General Discussion Engines GMC SBC valve swap

The Jummy head is cast with a 1/8" deep valve pocket the width of the valve spring to locate the spring so no locaters are necessary. Everywhere I have read says to use a SBC valve spring +0.100" in length ... which is half the 0.21" it seems to be too long. If I had used a SBC spring at -.100" I would be right on the installed height. I have reinstalled and measured the old valve and spring and it is about the same as the new ones. I am wondering if the previous owned ran into the same issue and just went with what it was. My concern is the spring pressure at 2.030" height may be way too low. The mfgr. spec is 120# at the valve closed height of 1.850" and 320# at 1.200" but it would never get that high. It will be much lower at 2.030". The free uncompressed length of the spring is 2.33" so it is only compressed 0.30" as it is installed.