Hi again. Glad to see that the mailing list seems to be on its feet
again. Kudos to the hard-working maintainers. Also, thanks for
shortening my mail path. I was getting messages with 100+ lines of
header and 2 lines of text. It's better now.
Update time. In the two years that I've owned my '79 MGB I've had to
replace the starter motor, fix the cooling system, replace the head
(should that be counted as part of fixing the cooling system? :-) and
most recently, have the carb cleaned and rebuilt. Not bad for a ten
year old car used as a daily driver, especially since the head problem
might have been avoided.
The latest problem was a stumbling and hesitation under acceleration.
I couldn't diagnosis the problem and (as it turned out) neither could
my favorite British garage. After a day of playing around they
decided to clean and rebuild the carb, and that fixed the problem.
That brings me to...
> I did get it started. It's not burning oil, but its running rich.
> Probably the carbuerator. Anyone prepared to provide a quick tutorial on
> the Zenith-Stromberg (I can't remember the model number).
I suspected my carb was running rich after it returned from the
garage. As luck and Lucas would have it, the carb problem had
occurred just after I ordered a Colortune, so it was waiting for use
when the car returned. Colortune, in case you haven't heard of it, is
basically a clear spark plug that allows you to directly view the
combustion flame. Yellow means rich, blue balanced.
So I tried out the Colortune and sure enough, yellow flame. Adjusting
the coarse and fine idle nuts didn't have much affect, so I decided to
adjust the needle. Dig around in my tools, can't find my adjusting
tool. Dig around again. Go through the toolbox twice. Hmmm. Oh
well, have to run the car rich for a day until I get a new tool.
Put everything away, clean up, put that last screwdriver back in the
toolbox, hello! What's this? An adjusting tool. Sigh...
The next day I put in a new air filter, adjust the coarse and fine
idle adjustments to mid-range and voila! Somehow everything is now
fine, a nice blue flame. Didn't even need the adjusting tool. Maybe
the old air filter was really clogged, or maybe it was just the ghost
of British engineering.
That's a testimonial of sorts for Colortune. Certainly it is a neat
concept.
Anyway... There is a Hayne's manual for Zenith-Stromberg carbs but
while it gets much praise from many, I find it incomplete. It
doesn't, for instance, say what the initial adjustments for the coarse
and fine idle nuts should be. (But the Hayne's MGB manual does.) It
details a complete breakdown and overhaul of the carb but not enough
(for my tastes) on tuning or diagnosing. Your mileage may vary.
> In particular, a while back someone told me that the electronic choke
> on these is a real dog, and that you can buy a kit to convert it to
> manual ( hey--- just like my '64 Midget. Now THAT'S progress... A
> couple of cans of primer, and this thing will look like a REAL car.)
> Anyone for or against such a conversion?
Electronic choke? The automatic choke on the Z-S in late model MGBs
is not electronic, just a simple mechanical choke w/ a thermostat
controlled by water from the engine cooling system. Pressing down on
the accelerator pedal (on a cold engine) engages the choke; when the
coolant water heats up the thermostat releases the choke. Fairly
simple actually, easy to clean and it seems (at least in my case) to
be reliable. Of course, I'm in Los Angeles where a cold day is 45
degrees. Still, I can't see why you'd want to convert unless you are
having problems. (And I believe it is illegal in CA.)
A related note...
Way back when, I was having problems with pre-detonation (I never know
whether to call it pinging or knocking) which I fixed by routing the
vacumn advance on the distributor directly to the manifold, bypassing
the TCSA. The TCSA (Transmission Controlled Spark Advance) is a
switch on late-model MGBs that prevents spark advance in gears 1-3,
presumably as a pollution control measure. This is a recommended fix
for pre-detonation and/or when de-smogging an MGB (cf., one of
Porter's books).
When I got my MGB back after the carb rebuild, they'd reconnected the
TCSA. I'm no longer having any pre-det problems, so I've left it that
way. Anyone have any opinions concerning vacumn advance and which way
the car "should" be set up? What's the effect on response and
pollution? Has anyone else with a late-model MGB bypassed the TCSA?
On an unrelated note...
In the thread about sway bars, someone said that Victoria British was
a collection of idiots. I've not had that experience. They've been
polite, prompt and above-board with me. The one time I consulted
their technical support it was neither great nor lousy. Their prices
are certainly competitive with Moss and TRF and I haven't had any
problems with backorders. On the other hand, I'm not buying
competition parts, so that situation may be different.
-- Scott Turner
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