Hubris, classical scholars may recall, is a Greek word
that is roughly equivalent to the old English word
ofermod, both meaning "overweening pride" or just plain
getting too cocky for your own good. In Greek tragedies,
tragic heroes such as Oedipus, Agamemnon, and the like
were often struck down in the prime of their careers
for the sin of hubris, of aspiring too much. At the
Battle of Badon Hill, Saxon king Aethelred Unraed (which
means "no counsel," meaning that you couldn't tell the
dude anything; calling him "the Unready" is a common
mistake in these weak piping times of peace) was overrun
by Vikings because he refused to take the advice of his
carls and take the high ground, instead choosing to face
the overpowering Scandinavian army on a narrow bridge.
The account of the time says he died "for his ofermod,"
which gets us back to hubris.
But aside from the fact that we all have classic cars,
what in the name of all that leaks, drips, sputters and
sparks does this have to do with British sports cars?
Last night, I went over to Andy Banta's house to help
him get his white MGB-GT started. Andy had finished a
head swap and installed new ignition components, but
he wasn't able to tell whether we were getting a spark.
With me doing the important job ("okay, Scott, you sit
in the car and turn the key when I tell you"), we figured
out what was wrong and got the car started.
After that, I did a quick carburettor tune; both carbs
were too rich, based on the noise they made when you press
the lifting pin, so I got them to do the right thing (idle
rises slightly, then drops), checked their flow with the
Unisyn, and put on the air filters. Andy spoke well of
the car's feel just while moving it out of the driveway
so that we could move my B into the garage to do some work
on it.
My problems were an increasing seepage of coolant from
between the #2 and #3 cylinders, noticeable under the
spark plugs, and a general rough idle caused from the fact
that I hadn't done a complete carb tuning since I bought
the car. It had always run well enough that I could fiddle
with it for a minute or two and promise it to do the rest
later.
Andy got the valve cover off (praise to Burnett Motors in
Palo Alto, who installed the gasket correctly by fixing it
to the valve cover with Permatex copper gasket sealing
compound; this meant we could reuse the gasket as long as
we cleaned the top of the head nicely, which we did) and
we loosened the nuts a quarter-turn apiece. I dabbed the
seeping coolant away from the front of the head while
Andy gave the nuts a preliminary torquing; I took over to
recheck all the nuts a couple of times, making sure to hear
the click and not to see any movement from each nut. When
I was satisfied, I wiped the side of the block clean so
that I would see any new seepage, and we adjusted the valves.
There had obviously been some room for tightening, as the
valves (which had sounded loose before) were now far too
tight. After explaining the Rule of Nine to Andy (see which
valve is pushed all the way up, subtract its number --
counting from the front of the engine -- from nine, and adjust
that valve), we measured all eight valve clearances in a
few minutes and buttoned up. We put the valve cover
back on, and then we ran the engine to get it to warm up
and also to burn any coolant out of the oil.
Then we removed the air cleaners from my car and set about
doing the carburettors. As I knew from changing the plugs
not long ago, I'd had the carbs set way too rich; a push on
the plunger made the revs rise by a couple hundred RPM, or so
it sounded. So I loosened the linkages and started twisting
the mixture adjusting nut.
In a matter of minutes, I got the front carb just right -- a
blip as I push the lifting pin, then a drop back to the
initial RPM level. The rear seemed to be giving me more
trouble. I checked the flow on both of them, dialed the
idle down to just below 1000 (noting the wonderful smooth
sound of an engine with properly adjusted valves, and
promising to fix the exhaust leak where the header met the
downpipe when we install my new exhaust system someday
soon), and rechecked the mixture. Now the rear was too
lean. I dialed it a couple flats richer, but it still
dropped the idle farther than I liked. But it was late,
and I knew that putting the air cleaners on would enrich
the mixture, so I matched the flow on both carbs, tightened
the linkages, and put on the air cleaners. We put the
tools away, put the rightful MG in the garage (Linda's
'64, to be specific), and did a little computer mischief
before I headed for home.
There's that off-idle stumble at 2000 RPM, I noticed as I
turned out onto Meridian. Only it's much worse now. The
car was still stone-cold, though, so I gave it some time to
warm up. (Unfortunately, with my new fan and my new water
pump, the car takes a LONG time to warm up when it's in
the thirties, as it's been at night here lately.) The car
ran well at 3500 RPM, as long as you kept the throttle constant.
We hadn't checked the dashpots, and I hadn't filled them in
a couple of weeks -- yes, that would cause an open-throttle
burble, if the dashpots weren't being damped correctly. I
got home at midnight, and decided to touch things up in the
morning.
So this morning, sure enough, the dashpots weren't exactly
dusty but they sure didn't have any liquid oil in them. A
cap and a half of Marvel, a squirt of Castrol for good
measure; I checked the cylinder head for signs of leakage
and saw nothing, so I dropped the bonnet, pulled out the
choke (we won't talk about how I keep the choke pulled out
now that it's missing the knob on the end of the cable)
and started the car.
It started beautifully, in spite of the fact that Kim had
thrown a snowball at me (made out of the frost she had
scraped off the windshield of the Biscuit Tin of Steel)
that morning. While it idled, sounding wonderful, I wiped
away condensation (much of which had already thawed) from
the outside and inside, popped the car into reverse, and
motored smartly off down Heatherstone Way.
It was fixed! No off-idle problem, smooth acceleration,
much less of that 1800cc-sewing-machine noise from loose
valves. I was happy.
Until I released the choke on the freeway and some, though not
all, of the off-idle stumble returned. True, the dashpot oiling
had helped, but my haste in reassembling the carbs had left
the rear a little lean. With the choke pulled out, the mixture
was rich enough, but when I let off on the choke, the problem
came back.
So my lessons? First, of course: Don't put the tools away till
you've road-tested it. But also, note that this is the classic
mistake of adjusting SUs (or any multiple carb setup): tuning for
a smooth idle will get you a smooth idle, but you don't drive at
idle. Fortunately, it's just a matter of twisting the mixture
adjusting nuts a couple flats downward, but it's still frustrating.
At least I don't have to disassemble it and install new jets!
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