Calling all Triumph devotees! I need some help here, and sorry for so many
questions in this email.
I'm doing the valve clearance on my TR7for the first time. Engine is stone
cold, spark plugs out. I put the car in gear and move it to rotate the cam.
Initial valve clearances, starting at the front of the engine and working
back are as follows:
#1
.012
.005
#2
.005
.012
#3
.012
.007
#4
.007
.012
All too low, assuming I want specs of .018 exhaust and .008 intake. And
judging from the sequence, I assume the valve order, starting in front, is:
#1
exhaust
intake
#2
intake
exhaust
#3
exhaust
intake
#4
intake
exhaust
Is that correct for a TR7?
Now, the problem. #2 cylinder exhaust shim is .091. Valve clearance needs
to be increased by .006, so I need a .085 shim. Same problem for #4 cylinder
exhaust shim, but as far as I know, .090 is the smallest shim I have seen
sold by Moss, RTF, Victoria British, etc.
So, what could be the problem? I checked the valve clearances twice, and the
micrometer readings a billion times, but I guess I could have done something
wrong.
Is it possible a previous owner milled the head and didn't use a thicker head
gasket? Or a valve job was done and the seats were ground too deeply? Or
could there be a special setup with the valves that need less clearance?
So, does anyone sell thinner shims? I hear rumors that other shims might fit,
maybe from a Saab 99, Lotus Elite, and others that have shims thinner than
.090. Anybody done this, and is there a good place to buy them?
And for my worst exhaust valve, we're only talking .005, so couldn''t I buy
some extra extra-fine wet sandpaper and use a circular rubbing motion to sand
the shims down a bit? Do I have to polish them afterwards? Maybe better to
take to a machine shop?
And I have seen comments about keeping the exhaust valves at .012. Won't
they burn if they're too tight? Someone suggested my cam might not be
standard, and the closer tolerances correct. Since I bought the car used,
how would I tell?
And finally, should I even be worrying about all this? Again, I always
thought that tight valves could be a problem.
Any/all advice appreciated. And as always, thanks!
Bruce
1980 Inca Yellow TR7 5-speed convertible
Chapel Hill, NC
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