Dan, the two piece exhaust valve retainers were designed to help the valve
rotate while in operation. This was believed to help prevent valve face to
seat hot spots from forming. I may or may not be correct with respect to the
spitfire engines. I do know that rotating valves were used on some passenger
car engines, most big truck engines and off road equipment engines.
Bill G
-----Original Message-----
From: DANMAS@aol.com <DANMAS@aol.com>
To: spitfires@autox.team.net <spitfires@autox.team.net>;
triumphs@autox.team.net <triumphs@autox.team.net>; GuyotLeonF@aol.com
<GuyotLeonF@aol.com>
Date: Monday, November 23, 1998 9:42 PM
Subject: TR6 restoration - update report
>Listers
>
>First of all, a great big thank you to the members of the list who
contributed
>so generously to the restoration fund, to Leon for covering the cost of the
>repairs to the hood, and to the rest of you for your moral support. I won't
>mention every one by name, because I'm not sure every one would want me to
>(some of the contributions were sent anonimously), and I have tried to
thank
>every one individually, either by e-mail, or by snail mail. If I didn't
thank
>anyone, please excuse me, because e-mail is often lost, and accept my
thanks
>now.
>
>Now, on to the gory details:
>
>Firstly, when I removed the nuts holding the intake/exhaust manifolds on, I
>found NONE of the nuts were much more than finger tight. The "soft" gasket
>material had squeezed out from the metal "sandwich" around the first two
and
>the last two cylinders. For the most part, there was nothing but the metal
>left in place. On the intake ports for cylinders 1, 2, 5, & 6, the gasket
>material had squeezed into the port area, and had blocked off about 1/3 of
>each port.
>
>Secondly, the head is warped a bit between cylinders 2 & 3. I could slip a
>0.0025" feeler gauge under a straight edge in this area. Everywhere else,
the
>head was in good shape. I thought I would find a blown head gasket, but
this
>was not the case - the leakage I was getting between these two cylinders
>during the leak-down test was from the warped cylinder head.
>
>Thirdly, and this is really puzzling, I found some exhaust valve recession.
>Valves for cylinders 1 & 2 had recessed about 0.010", while the valve for
>cylinder 3 had recessed a whopping 0.040" (these are all approximate
numbers,
>as I have no precision method of measuring the recession). Just to
confuse
>the issue, the other three valves were in PERFECT condition - no sign at
all
>of valve recession! This is after 20,000 miles of unleaded, regular gas.
>Obviously, the gas was not the problem, or all six exhaust valves would
have
>shown recession.
>
>As I reported earlier, the car was idleing and running fairly well when I
left
>Blacksburg, with a slight "put-put" from the exhaust, indicating a possible
>burned valve. By the time I got home, 250 miles later, the car would barely
>idle. It still ran well enough at speed, but not at idle (you must
remember, I
>had been driving the MGB for the previous two weeks, so even running
poorly,
>the TR6 seemed to be running strong by comparison, so I was not as
sensitive
>to any performance degradation as I normally would have been). When I
checked
>the valve clearance the next morning, I found zero lash on some of the
valves.
>Unfortunately, I didn't make a record of which valves had zero clearance,
but
>all of them were on the low side.
>
>I know what I need to do, and the head will go into the shop for truing and
>valve seat repairs, but I haven't a clue as to what caused the problems.
>Anybody?
>
>I'll be digging into the lower end next, and will post another report when
>that is done. I will check the cam lobes for any excessive wear, as well as
>the other routine checks.
>
>One quick question while I have your attention: The upper retaining collars
on
>the exhaust valves are two piece, while on the intakes, they are one piece.
>Anybody know why? Just curious.
>
>Thanks again to every one - your interest and support means a lot to me.
>
>Dan Masters,
>Alcoa, TN
>
>'71 TR6---------3000mile/year driver, fully restored
>'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion -
see:
> http://www.sky.net/~boballen/mg/Masters/index.html
>'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
>'68 MGBGT---organ donor for the '74
>
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