It's been said that the North American roller head's valvesprings are only good for 7000 or so RPM. This confuses me, because Primeras with SR20DE roller heads don't stop untill 7200 RPM. These two facts may be neither here nor there, depending on the answers to these questions ;) :
Are the springs from roller and earlier models interchangable (same static height, compressed height, coil breadth, and so on)? If yes, has anyone tried doing this, esp. with JUN or JWT valve springs? If no, are springs available (even non-US vendors), or can springs be custom made?
3 is a pretty tall order, but I gotta' ask. :) It seems to me that doing the standard I/H/E and S3 cams on a roller SR20DE is not a wise investment if we can't get past the 6700 RPM point...

Looks like we're all b13/b14 people here, huh? I guess we don't have enough experience with the newer head yet.

Wll, Andreas has mentioned once or twice that he's had a roller head on-hand. I'd be pretty happy with some rough measurements to start off with, like barrel diameter and height. :D

As for not having enough experience with the new head, you seem quite right about that. It's almost as if the SR20DE was retired two years ago. I suppose for a couple of years low-port owners were left in the dark, too, so I'm not upset, I just wish that somebody (with more time and money than me) would start harvesting real information on my block and head. :(

Talk to Chris at SR20development he was doing alot of research on the roller motor

What is a roller cylinder head?

Roller cylinder heads are used in '00+ Sentra SE 2.0s, I believe '99+ G20s, and I have no idea how many non-US models. It's much like a low-port head, except that instead of using flat lifters against the camshaft, they have a small roller, which reduces friction and allows for cam proviles never possible with flat lifters. It presents an engineering challenge on many fronts, because a roller lifter has to be aligned with the camshaft, whereas flat lifters can rotate freely. I just want to know what all does fit from the older Low-Port cylinder head.