In reply to a message from ricasso sent Thu 28 Jun 2007:
Mike
The ‘rounded stem’ of the bad valve almost certainly means a
replacement is called for.
But that sets another puzzle. How on earth did the stem on
that one valve become ‘rounded’??? One of the beauties of
the Jag cam follower ‘bucket’ arrangement is that the valve
stem gets only direct axial force via the shim to push it
down, the ‘bucket’ absorbing the side thrust as the cam
slides over it.
Is that valve guide badly worn by any chance, causing the
valve to ‘chatter’?
Whatever the answer, I guess you have to get a new valve for
that #5 cylinder position and assemble it and the camshaft
to the head to measure the new valve’s clearance before
deciding on the shim thickness required to bring that within
spec. Don’t forget that when you measure the valve cleances
with the head on the bench, they will become perhaps 1 to 1�
thou tighter when you have finally bolted the head to the
block and torqued the head bolts down fully.–
The original message included these comments:
this was when I discovered the bad valve was exhaust no 9 [counting
from the front ie camchain end.
on inspection the valve was strait but stem end rounded over in
comparison to the other valves[a good reason to replace the valve?]
–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !