340 xhead spring shimming, height and pocket question(s)

4spdragtop said

Heres a screen shot of Summits PSI recommendations for SFT cams.
Agree? Disagree?

View attachment 1716052191

Click to expand...

I think that is pretty much the spring you get plus or minus a few pounds, if you buy a set of ProMaxx or other heads that is setup from the factory for a FT cam. That doesn't mean that they are optimum for every FT lobe. I'm sure there are agressive lobes that would want more spring.
I'm going through this as well. I think the Comp tech is covering his rear end recommending a spring that is 140-ish on the seat and 390 at .550" lift. For a standard length valve, there aren't any springs that can support that, but I'm sure that guys have been running similar cams on OEM heads for decades.