Porpoising can be a pain. One situation that I think Buddy has mentioned before is where the car dead hooks & winds-up the sidewall, then can't keep the pressure applied as the car tries to get "up on the tire". The car then "falls off" the sidewall, and then re-winds the sidewall all over again, in a continous cycle.
Another is more of a "skipping" tire shake, where the car winds-up the sidewall, then spins, then re-winds again in a continous cycle.
And as you said a over sprung car can do this too, as it tries to use the sidewalls as a makeshift spring.
I think the Santhuff's top shock window has around 18 sweeps from full tight before you can't get a tool in the window anymore, & the bottom knob is at least 20 clicks from full tight. But I doubt that most people will really need any settings looser than 10 sweeps (or clicks) from full tight. Going past 10 from full tight might not have any real effect anyway, only a shock dyno could tell you for sure.
There's a few people on here that are around the D/FW area, I'm in Kennedale. Duane & Glenn are also in the D/FW area, but I seem to recall that others on this site are also in the larger general north Texas area.
460 street '66 Ranchero.......................finished someday.
460 race '70 Maverick..........................finished someday.
All 'glass Top Sportsman '69 Mustang......ummm, check back when I win big playing the Texas Lotto, or online poker.
page. Some ancient & newer local race video.
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