am I correct, the valve doesn't rotate generally?

this is my question, do the valves rotate in the guide? i mean unlike that of old flat tappet car engine but even that just spins the lifters and not the valves, correct?

I can’t see where there is a spin induced but nor is there anything that would stop some rotational movement.Guess you have to be there.

agree, but surely someone knows whether it'd be considered common or not. 
maybe i smoked one eye closed and couldn't see outta the other LOL

Like rings they will rotate but not very much. 
Steve

Valves do rotate in normal operation. There are some vids online showing this .

As I understand it, the compression of the spring tends to turn the valve in one direction, and the decompression turns it back. But since it's under more force during compression due to inertia, the compression rotation 'wins out'. I've also read that the rocker arms can be set slightly off-centre on the valve to turn the valve as it pushes down, but I've never measured. But don't quote me on this. Suffice to say - the valves will rotate in normal operation on most engines.

Some engines use a mechanism to ensure rotation using a ball and ramp system, similar to a starter clutch. I would guess this is to introduce more rotation than is exerted by the springs.

Valves can rotate - usually at higher rpm.
over the years some engines have been designed to ensure the exhaust valves rotate to keep the seats clean.
if you do some research on Youtube you can find some interesting stuff - especially videos inside an engine of the valve train at high rpm - it looks really scary !

Valves do rotate on higher rpm!

wrote:

Valves do rotate on higher rpm!

+1

yes sir that's the information I was seeking. 
and the double springs are to thwart floating the valves at high rpm?
what's the best tool for measuring when checking your valve tipping length (for the DIY's) I have a 6" dial caliper but not sure if that'll suffice or maybe there is something better?
 

wrote:

yes sir that's the information I was seeking. 
and the double springs are to thwart floating the valves at high rpm?
what's the best tool for measuring when checking your valve tipping length (for the DIY's) I have a 6" dial caliper but not sure if that'll suffice or maybe there is something better?



 

You need to take the installed height measurement from the valve tip to the bare head with the steel spring seat removed.
If the valve is stock then you can take off 0.30 mm .
Any more and you can trim the collets and retainers if they are shim on top by a max of 1mm.
A vernier depth gauge can be used but that is tricky and can give inconsitent results even for the non diy-er.
A height gauge as in the pic of the correct minimum length is the only way to get reliable readings.



 

i do believe that .010" was taken off the valve, so from .11mm clearance with a 2.00 shim, so i'm thinking this should put my shimming in the 2.35 or 2.40 range?

The cam lobe is not centered on the bucket/shim, so there is a little rotational force going on.  The offset is to spread the wear on the shim/bucket.