How To Measure Valve Guide Clearances

[revilla]

The Rover K Series Overhaul Manual gives instructions on measuring the valve to guide clearances as follows:

Should I be measuring these as A or B in the diagrams below?

I kind of assumed method A (so carefully pushing both top and bottom of the valve to each side to keep it flat against opposite sides of the guide) as this measures the actual running clearance between the valve and the guide. But videos on the internet always seem to show method B (so rocking the valve head as far as it will go to each side, which typically gives about 3 to 4 times the measurement of method A).

If it is method B, my guides have had it - but so have the brand new valve and guide I bought from Rimmer to compare  

[oilyhands]

In my experience even new heads (especially VHPD ones) often exceed the stated clearance when measured as recommended. There is a certain amount of 'feel required when assessing guide wear and it would be wise to measure the movement across at lest two axes.

Oily

[revilla]

PS: Suggestions on the Internet seem to be that you measure A with internal and external micrometers, or measure B and divide by 2. But by my reasoning below, assuming that in the position at which you measure it the valve head protrudes throug the the guide by an amount approximately equal to the length of the guide, the factor is 3. And in reality I think by the time you have 10mm lift as described the head is more than one guide length out of the guide, so the factor is close to 4.

[revilla]

Thanks Dave. I'm measuring about 3 times the specified limit using method B. Is this correct?