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Q & A: Zenith- Stromberg Throttle Response

I acquired '79B (Arizona car - NO RUST but sorely neglected). Because it
had no rust I decided to spend some money on it and I have done a lot of
work to get it back into original condition (in some cases maybe better
than original). I tend to lean toward originality (I even like the
backfire on deceleration). I have replaced the entire interior, dash,
windscreen, front end rebuild, clutch assembly, all new chrome fittings,
new top, had it professionally repainted to original Russet Brown while
I had all the lights and chrome off (wish it were BRG like my '74 E-type
I bought new and let slip away- no kicking necessary -- I've already
kicked myself enough), etc. etc.. The intent was to end up with a nice
stock car. I don't mind spending whatever it takes to get it running to
match the way it looks. It was running fine (idle was rough but
tolerable) when I acquired it and gradually went down hill. Till it
finally got to the point that down hill was about all it would do.


Carb was so rich the heat from the catalytic converter melted the
plastic knob on the damper. I replaced the damper and the EGR and Gulp
valve as a precaution thinking the diaphragms might fail from the
effects of the heat and leave me stranded. And while I was doing that I
went ahead and replaced the PCV valve. The pump seems to be fine. The
diaphragm in the carb is ok. All of this took place before I found your
web site.
Enough background.

Now, when I release the throttle between shifts, the rpm will
momentarily increase then about a second later drop off to an idle. A
second is really a long time when you approach a traffic light and let
off the accelerator and the car continues at speed for that second
before decelerating. The carb is still rich and I am waiting on an
adjustment tool to correct this. I don't know if it is going to solve
the problem. I've been told this was normal. If so, isn't this a little
rough on the clutch? not to mention dangerous in a sudden situation when
you need to stop quickly? Have you ever run across this before? Any
suggestions would be appreciated. I am not very familiar with MG having
only had this on about a year but am not a stranger to auto mechanics.

I have read your article on detoxing and on those damn Zenith-Stromberg
carbs. I have also ordered your technical manual.
Do you recommend detox? Is the result really worth the effort? I would
prefer smooth running and idle over originality in this case, but if
good idle and smooth running can be obtained with originality that would
preferable. We do not have emission testing in this part of the state
but any knowledgeable mechanic would miss the pump and fittings -
especially on a later year car.

Thanks for your time. I wish I lived closer to your location and could
just drop this off to have it tuned up.


Ed Dudley

ED!

The problem you describe is caused by problems in the emission
control system. If you remove the smog system, and do it correctly, then
all these problems will disappear (except the richness). Let me try t... read more