> Date: Thu, 2 Dec 93 11:57:18 -0800
> From: paulh@wv.MENTORG.COM (Paul Hemson)
>
> My 1980 MGB with a ZS carb doesn't want to idle at a sensible speed and I'm
> hoping someone can give me some pointers.
I have a TR7 with a pair of ZS carbs. I'll try to help.
>
> When it's cold everything seems to work o.k (at first). It starts o.k and
> idles at somewhere around 1200 RPM (which seems o.k.). If I then drive it for
> a few miles everything seems to behave normally until I stop and let it idle.
> The engine is then idling at around 2000 RPM. Despite this it runs smoothly so
> I thought the automatic choke probably isn't sticking open. I thought that if
> the choke was stuck open the mixture would be way too rich and it wouldn't
> idle smoothly. I know that the throttle isn't sticking open because I can see
> from looking (and feeling the carb) that it has returned to the start
>position.
>
This sounds like what my TR7 does when the coolant gets low. The problem seems
to be lack of coolant to heat the (coolant controlled) choke to close it.
The problem goes away as soon as I add coolant. This is the automatic choke
on a pair of 1980 carbs, with the choke basically being a third mini-carb with
a black (phenolic?) cap.
>...
>
>...
> and I don't know which position is which, I still seem to get cold air
>blowing
> in. Neither position seems to change the way the heater works.
You may have clogged heater lines and carb/choke heat lines. Run a hose through
your system with a couple diconnected, and see if anything comes out. I had
one clog real bad once, causing a similar problem. When I backflushed it with
one of the hoses off, all kinds of crud came out.
>
> Thanks in advance for any suggestions.
No problem.
>
> Paul.
>
> paul_hemson@mentorg.com
Good luck,
Kevin
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