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I really like the idea of using 7mm stemmed valves, but would need to fit new guides to my heads, but unfortunatly, I can't see them listed. Is this the case?!

http://www.aircooledtechnology.com/stor ... hp?cat=280

Yes, you will need a full 7mm set up from the guides to the valves and retainers.

7mm set ups are custom order and not shelved.

Jake, going from a 9mm to a 7mm setup would add *about* how
much rpm potential with the *same* parts, i.e., the 9mm setup
would be good for 6500RPMs, where the 7mm setup would be
good for 7500 RPMS, resulting in a 1000 RPM increase in capability?

Not looking for total accuracy, just wanting to try to gauge the
$$ per RPM increase, when going to 7mm.

And yes, I understand that the reason to *go* to 7mm would
normally be because the combo dictates it, but some folks just
want to have all the bling, weither it is needed or not.......


Don

To shorthen the answer, whats the approximate (to the g) mass of say a 42mm x 7,8,9mm stem ?

Also how do the corresponding retainers vary in mass?
Collets I guess are ligher the samller you go (8mm weigh in at 2.5gramm a pair).