rgb@exact.com wrote:
>
> Thanks for the info.
De nada... easily done. <g>
> If you have oil pressure concerns at hot idle, i.e. after a 10 mile
> 60 mph run, then replace all the lower bearings and thrust washer.
Since this car is my only transportation at the moment, I did a very
quick in-the-car re-ring over Labor Day weekend, and I was fairly
dismayed at what I saw inside. Looked like it had been running the same
oil and filter since the day it was new. Everything inside polished from
dirty oil, I replaced all the rod bearings, and one rod with a stretched
big end, but when I saw the condition of the crank, I figured I better
not replace mains and thrust--the scoring on the crank would have shed a
lot of metal from brand new bearings. Oil pressure is better, but given
the wear I see elsewhere, there's probably a considerable amount of loss
past the cam journals along with most everywhere else. At least I have
the 75 mi/qt oil consumption stopped. It actually looked as if standard
rings were installed without honing the cylinders on its last rebuild.
(!) The only way to really fix this engine will be to find time to pull
it and go through it completely.
> This and a new rocker set cured several car's problems for me.
> Now I adjust the valves when "I" feel like it, about once per year...
I mostly had the rocker set rebuilt in the hopes that the noise would
diminish--I only had three worn sets to choose from, and none could be
adjusted properly.
Okay, got one for you--I mostly know SUs and Webers, and am still
getting used to 175 Strombergs. In the last couple of weeks, as the
weather has gotten colder, the engine has a pronounced hiccup off-idle.
Idle seems to be reasonably steady. Don't think I have any external
vacuum leaks (if big enough, that would affect idle as well, one would
think), and that would suggest temperature compensator, but the book
says that would cause a rough idle.
With the air cleaners off, it's fairly apparent that the vacuum is
dropping a lot with throttle movement--the air valves move up with
moderately brisk throttle opening, the engine coughs, air valves drop
about 1/8-3/16" and the engine recovers, and this goes on, with the air
valves oscillating a little less until the rpm goes above about 2500,
and then it smoothes out. Timing is fairly conservative (8 deg. adv.,
plugged retard line), just put in new plugs, gapped for the electronic
ignition, checked the plug wires, and they're good, replaced the cap and
rotor (did a poor man's oscillosope test by checking each wire at night
with the timing light, and there's no break in spark frequency when the
throttles open, so I don't think it's ignition related), float levels
are approximately right, damper oil is up to level, air valves aren't
sticking. Both air valves behave almost identically, so I don't think
it's carburetor balance, although I haven't checked it. Five of the six
old plugs showed a fair amount of soot on them, and the mileage is down
a bit (a subjective measurement, since the third used speedometer I've
installed has quit <g>).
I'm left with bypass valves. Both are weeping a very small amount of
fuel past the screws, which suggests the diaphragms or gaskets are going
bad, simultaneously.... Can leaky bypass diaphragms cause this sort of
driveability problem? Any other suggestions or possibilities? The
factory manual is quite unclear on the function of the bypass valves,
except to suggest that they bleed air on decel, so I don't understand
why I would see fuel leakage at that point.
Cheers.
--
My other Triumph runs, but....
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