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xflow valves
MkII - 23/4/10 at 09:19 PM

Ive had the valve guides replaced and bought new valves,collets and retainers for my 1600 crossflow but if you assemble the valves,collets and retainers off the head and without the springs there is some play between the valve stem and the collets, one of the reasons ive replaced the parts is that when I stripped the head I found 2 broken collets, do you think the play between valve and collet is going to cause the same problem again? .thanks .m.

MakeEverything - 23/4/10 at 11:18 PM

quote:
Originally posted by MkII
Ive had the valve guides replaced and bought new valves,collets and retainers for my 1600 crossflow but if you assemble the valves,collets and retainers off the head and without the springs there is some play between the valve stem and the collets, one of the reasons ive replaced the parts is that when I stripped the head I found 2 broken collets, do you think the play between valve and collet is going to cause the same problem again? .thanks .m.


The collets are pressed against the top of the valve and the spring seat, so as long as they fit into the recess it should be ok? For the sake of a few quid, is it worth getting new valves and lapping them in?

snapper - 24/4/10 at 05:21 AM

Collets are designed to be a loose fit, this allows the valve to rotate. On high performance Pinto's some builders rub the collets on wet & dry so they are atight fit, this is to prevent the locating grooves on the valve stem from burring.

[Edited on 24/4/10 by snapper]

[Edited on 24/4/10 by snapper]

richardlee237 - 24/4/10 at 06:16 AM

With normal manufacturing, it is impossible to ensure that the centre of the hole in the spring carrier will stay on the centre line of the valve as the valve is depressed. Hence there is some clearance between the collets and the valve stem to allow the 2 components to align. Without this there would be a side load imparted into the valve stem causing excessive wear of the guide or even failure of the valve stem.