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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [xj-s] Valve Stem Seals
Hi, I had a head re-worked by specialist over here, including valve seat inserts, The engineering shop I used also didnt use the Jaguar items, preferring to use a speacialist supplier of hardened seats. That car has since done 35k miles without incident. David Low ---------- > From: Kirbert <palmk@mailer.gadcomm.net> > To: xj-s@jag-lovers.org > Subject: Re: [xj-s] Valve Stem Seals > Date: 29 July 1998 14:17 > > > From: John Napoli <jgn@li.net> > > > Unrelated. We're talking about overheating the head after shutdown > > > causing the valve seats to drop. > > > > Has anyone contacted the valve seat insert manufactureres to hear what > > they have to say about what makes these things drop out? > > Not I. Interesting issue, since I learned a bit getting a new seat > installed. First off, the OD needs to be some sort of standard since > the recess itself is cut with a bit. I didn't expect this, I thought > they'd be cutting the recess with a tool with a variable diameter and > could make it whatever size they wanted. > > Anyhow, in concert with this, they couldn't care less that Jag > offered oversize valve seats, they were providing their own -- in the > proper OD, of course. These reportedly are thicker-walled than the > Jag items, so AFTER installation they then had to machine the ID of > the seat to the same diameter as the other intake seats. Of course, > they cut a new seating surface, using the other intake seats as a > pattern, and -- get this -- making sure that the valve sat as close > as possible to the original height, so adjustment would be in the > same vicinity and compression ratio would be minimally affected. > > As far as asking the manufacturers why the things fall out, I am > pessimistic. I am getting frustrated asking Bywater such questions; > everything is the owner's fault, Jaguar never did anything wrong. > The centrifugal advance mechanisms seize because owners didn't lube > them properly; pointing out that many (most?) owners were paying the > Jag dealers exorbitant amounts for scheduled maintenance AND that no > OTHER makes of cars had similar distributor seizings despite > undoubtedly comparable lack of maintenance doesn't faze him. The > valve seats fall because owners overheat the cars; pointing out that > my Hondas also have sintered iron valve seats in aluminum heads and > that a falling seat is unheard of, overheating or not, likewise > doesn't elicit any admission that Jaguar did anything untoward. > > -- Kirbert | If anything is to be accomplished, > | some rules must be broken. > | - Palm's Postulate
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