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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