After all that was discussed here in the topic ‘‘mildly
erratic engine response’’, I’m planning to soon adjust the
valve clearances of my engine. I know this might sound as a
simple work for most of you, but pls consider that in my
country a Jaguar is a strange thing and that I’ve never seen
the innards of a Jag V12 engine (though I’ve successfully
rebuilt a BMW V12 engine). When I say that, what I mean is
that I’ve supervised a mechanic (who knew nothing about that
particular engine) doing it. I’m a mechanical engineer in
the business of motorcycle engine repair and rebuild.
So far I’ve read Kirby’s book related pages and also looked
at Bernard Embden’s www site explaining how the timing chain
tensioner works. BTW, tks to both of them! Anyway, and
though my English might seem quite OK (it’s my 3rd
language), I always fear to misunderstand something. So here
a couple of questions:
Brittle tensioners tend to break when fully retracted
(straight position), that’s a fact. After explaining all
possible precautions to avoid it breaking, Kirby’s book
tells you NOT to retract it and just let the sprockets
engaged in the chain and hanging from hooks in the housing.
When re-installing camshafts just rock the latch to release
the extra chain tension. IS THIS SO? Or did I understand
Cam cover oil leaks are no news, especially the moon
seals. Did I understand correctly that one solution is to
put new half moons, but NOT to put ANY gasket and use
‘‘gasket maker’’ cement all the way and especially above and
below the new half moon??? (BTW I’ve used in the past a very
good German made ‘‘Victor Reinz’’ brand gasket maker that I
can easily buy locally). This would allow me not to need to
import the gaskets, with the big risk of them being nicked
(destroyed) in transit or customs.
As most probably I’ll have to enlarge the valve clearance
gaps, I’m tempted to lower the existing shims, also to avoid
the complicated freight and customs bureaucracy involved in
importing new finer shims. I know a guy with the proper
tooling (a magnetic bench) to do such work. Does anyone see
a problem here? Or should I better go for thinner original
Additionally, I’d appreciate any kind of advice from you
experts regarding this work.
Tks in advance & rgds, Luis.
PS The saga ‘‘in search of a more stable idle’’ will follow…–
Luis Gasperini / '91 V12 XJ-S conv. 5sp
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