thanks for the input guys.
So to summarize "correct when wrong"
It is safe to use a valve spring with the od of 1.26"
on a alloy cylinder head that has a spring pocket diameter of say 1.54"
However At the least I will need hardened shims to stop gailing of the head, or preferably spring locators or cups.
Installed spring height obviously needs checking.
I cant help but feel that there should be something stopping the bottom of the spring from moving.... A spring locator will obviously do this, however I cant find any listing on summits site of a shouldered locator that has the correct od for pocket & spring fitment.
any ideas lads?