Have the valves been adjusted lately? I had someone who knew what they were
doing help me with the valves and they were all a little off and I do notice
an increase in power. Gives a better exhaust rumble, too!
Giving money and power to government is like giving whiskey and car keys
to teenage boys. -(PJ O'Rourke)
Steve Conley
Marysville, WA USA
'76 MGB Roadster
GHN5UG393585G
mailto:swconley@foxinternet.net
MGB Online = http://web3.foxinternet.net/swconley
-----Original Message-----
From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net]On
Behalf Of Tom McLaughlin
Sent: Friday, November 12, 1999 12:32 PM
To: MG list
Subject: Mixture problems???, 77B
All,
Not sure If I have enough details or knowledge to
explain for the list to help, but I thought I would
give it a shot.
Specs:
77B, Z-S carb, desmogged, Pertronix Ignitor ignition
Symptoms:
The car started to idle lower and lower over a period
of about 2 months. It also started to lose a little
power. As I was in the process of getting married, I
did not troubleshoot, but just increased the idle so
it would not stall. Finally, I had some time and the
car had lost so much power that it was not as fun to
drive.
What I've done/checked:
I looked for vacuum leaks (started the car and sprayed
carb cleaner all over the place) and could not find
any.
I decided to go through some regular maintenance items
as I hadn't done so in a while. I replaced the plugs,
checked to make sure I had a good spark and checked my
timing. It is set to about 10 degrees BTDC at about
1000RPM idle. I figured the ignition side would be
okay as I put in the ignitor and replaced most parts
about 6 months ago.
Remembering that I had this problem before, I checked
the diaphram in the ZS carb. It looked okay, but I
had a spare and thought there might be a pinhole so I
changed it. No real change.
Next, I replaced the fuel filter as it needed it. No
real change.
Next I replaced the air filter (the element) and
vrooooom. The car started great and the idle was up
to about 3500 RPM. The old filter was very dirty. I
was getting some black smoke out of the tailpipe so I
guess I was running very rich.
I readjusted the idle and it is solid now. It doesn't
search, but stays solid where I set it at 950RPMs.
The car runs well, but seems to not have as much power
as it used to before all of this started.
Read, think, read, think....perhaps now it is running
lean. I've adjusted the carb a bunch of times and
perhaps I leaned it out to compensate for the lack of
air because of the dirty filter??? I checked the carb
with my allen wrench tool thingy from Moss and it was
turned all the way clockwise....as rich as possible
from what I've read. I had to try something, so I
turned a few turns counter clockwise. It ran a little
better. A few more turns... a little better. I've
turned it so far that turning it any further doesn't
do anything more. Is it possible to unseat the needle
because you have made too many turns counter
clockwise.
It runs better, but still seems to have the lack of
power it did 3 months ago.
Fuel pressure is fine. Spark is fine. No vacuum
leaks as far as I can tell. It has to be the mixture
right???
The ZS does need some work. It holds the oil in the
dashpot for about a day. I have to top it off every
day or so. Other than that, it has been fine for the
last year and a half.
Hopefully not too long, but I wanted to give all the
details I had. Any thoughts...
I've been thinking of sending the ZS and autochoke off
to be rebuilt by a pro.
Please don't suggest throwing the ZS away and putting
on a webber. The ZS has worked fairly well for almost
4 years and I'm happy with it...until now.
Tom
77B
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