In a message dated 30/12/97 15:58:17, you write:
<< Hopefully, by the time you read this the discussion of unleaded fuel and
Triumph engines will have slowed down - a bit. But I need to air my two
cents worth.
I see three possible scenarios:
1. You have a car, you drive it.
2. You have a car, the power is down a bit and you decide to "freshen" the
engine.
3. You have a car, the power is way down and you to a leak-down and
discover that the head has problems (blow-by on one or more valves).
In each scenario, the owner has to make choices about how to fix things up
given that unleaded fuel is the only fuel available. Now, the folks in
Europe are repidly approaching the situation that we've had hear in the
states for over ten years - the phasing out of lead in fuel.
In all three scenarios above, you do not need to replace your valve seats
UNLESS YOU HAVE MEASURABLE VALVE RECESSION.
Take my advice: don't waste your money on hardened seats unless the valve
faces are flush with the combustion chamber. By installing hardened seats,
you are doing several things: one you are doing unnecessary work on your
head. You are adding a potential failure point (ref. Mr Guyot's valve seat
failure) and you are spending money that you don't need to spend.
As for driving at 55 m MPH, I have news for you. I've put close to 60,000
miles on my TR6 since they stopped allowing lead in the US. I have had no
problems with valve recession in my car. I've had the engine apart several
times and measured everything and there is no appreciable wear. Oh, I drove
over 5000 miles round trip to Ft. Worth, TX for the VTR at considerably
over 55 the whole time - more like 70 mph or more as that is the posted
speed limit on the other side of the Mighty Mississippi. Well, I admit - I
drove like I was in Texas the whole trip. Shucks. Less than 24 hours
driving on the trip home.
And I drive my car pretty hard. Come for a ride with me some day and I'll
show you some twisty little New England Roads at appreciably more than the
posted speed. And I race my car in local Autocross events at least 10 times
a year (more if my car is not torn apart). So, it would be safe to say that
I represent the upper threshold of applied engine stress...
Now, don't get me wrong - if there is valve recession, there is not a lot
of choice about new valve seats. But if you don't need them - why bother?
As for valve guides - that's another thing that you don't need. The stock
cast iron valve guides are plenty servicable for a long time. If you have
the head off the engine and you do a valve job, if the valve guides are
worn - then replace them. If you do a lot of FULL THROTTLE driving, then
you should consider the silicon-bronze replacements. If you drive more like
your grandmother (well, not like my grandmother - I'd have put the
silicon-bronze valve guides in her car) then the cast iron stock valve
guides are plenty adequate for a long service life - maybe over 100k miles.
I'll let you know when I finally replace mine - they only have 98,000 miles
on them and they are still okay.
Bottom line: Triumphs work fine with no-lead - really. And I'm not some
tree-hugging, save-the-whales type. If you really beat on your car, then
you might need the "full treatment (silicon-bronze valve guides and
stellite seats)", but for most of us, the stock setup is just fine for a
long life.
And, keep in mind that a lot of folks with these cars only drive them 2k
miles a year. That's 50 years of service on a standard valve job. Why pay
more money when there will be no return on investment??? I put over 9k
miles on my car this year and at that rate I shouldn't need another valve
job for about ten years.
Food for thought.
regards,
rml
>>
Bob,Thank you very much indeed for your considered response.
Basically,I agree with just about all you've said,and hope to goodness that my
Triumphs will indeed work just fine with unleaded fuel.
As I took 13 years to do a ground-up last nut n'bolt rebuild on my
Vitesse,with the head work being done back in '86,I don't have hardened seats
in it,although it does have the phosphor-bronze guides. I have so far put 2690
miles on it since April '97 when it was completed. I still need to redesign
the triple Weber linkage before I'm realy happy with it and get it on the
dynometer/rolling road before I put a lot more miles on it. Whatever happens
my Vitesse is only really a High Days and holidays car for use between May and
October,(this is England!),so total annual mileage is unlikely to exceed 5500
miles,even if (when),I take it on a Continental tour.
We lose our leaded fuel at 1st January 2000.
As it took me so long to get the Vitesse to its' present condition,(see
Triumph World #18,out in January '98),I do NOT intend to take it apart until I
am forced so to do.
Even though I finished it to Concours standard,and it has won a few pots,I
built her to drive!!! and that is just exactly what I intend to do with her...
Note also that our national speed limit is 70 mph,and not everyone here sticks
to it.
The police tend not to bother with anyone on our motorways unless they exceed
90 mph,or they are being otherwise stupid.
As it is presently 'untuned' and still on 'running-in' mileage,I have no idea
or my cars top speed etc,but it is somewhere between 110-125 mph,at my best
guess.
Whatever,it is well above the 55 mph figure as recommended by the Esso
Chemist.
So I intend to drive it and see what happens,as it seems I have little choice.
All the best
(and don't get caught speeding! ;-> )
Leon
ps.Happy New Year
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