The valves normally get TIGHTER over time (in my experience). This
is because the valve face and seat wear more than the pushrod, rocker arm, etc.
This causes the valve to rise higher, thus reducing the clearance.
If the clearance goes to zero it is bad, because the valve may not seat
fully, and the hot exhaust gas leaking out will wear it even more.
Doug Braun
'72 Spit
At 10:58 PM 6/5/2003 +0200, Emiel Rorije wrote:
>Today was a nice spitfire-preparation day, this weekend we will be cruising
>up the Costa Brava and along the French south coast. While doing my check of
>the rocker valve clearances I was thinking about the necessity of this
>procedure. I have always reasoned that due to wear the clearances can only
>become bigger, thereby producing a decrease in performance of the motor, and
>ultimately rattling of the rocker gear, but it wouldn't do any harm to the
>valves or the head.
>However if due to I don't know what reasons the clearance can also change in
>the direction of getting smaller that would cause trouble with overheating
>outlet valves etc. And make the rocker clearance check up all the more
>important.
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