I have had some recent trials/tribulations with the late model ZS carb as
fitted to California 1978 1500. Well adjusted and in good working order, it
is as smooth running as modern fuel injection. The basic carb itself is as
simple as the SU. The problems lie in the add-ons that make it emissions
compliant.
1. On the Midget, the carb is located directly above the exhaust manifold.
Not so bad until you also add a manifold mounted catalyst. Now it gets
REALLY hot.
2. Brass and Aluminum expand and contract at different rates.
3. With heat, the automatic choke gums up and makes the mixture too rich.
4. Too rich makes the catalyst run too hot. This creates more heat.
5. Diaphragms and plastic parts don't like heat. They get brittle and or
melt.
6. When the decel valve diaphragm gets brittle, it allows raw fuel to be
drawn into carb, and carbon canister system. This makes the car run too
rich.
6. The carb, head, exhaust and intake manifold expand and contract at
different rates. This creates vacuum and exhaust leaks. Both create
mis-fire conditions, dumping unburned fuel onto the catalyst. Unburned fuel
on catalyst=more heat.
7. Fuel line attaches to carb directly above hot catalyst. Fuel line gets
brittle due to, you guessed it too much heat. Fuel dumps on hot catalyst.
POOF!
8. Flames melt plastic parts. Plastic melts onto hot catalyst. Then
ignite.
Excellent sites with info on ZS carbs:
http://www.vtr.org/maintain/zs-tech-tips.html
http://chicagolandmgclub.com/techtips/556.html
http://chicagolandmgclub.com/techtips/559.html
http://www.sky.net/~boballen/mg/stories/TwistedZenith.html
David Riker
74 Midget
63 Falcon
70 Torino
http://personalweb.sunset.net/~davidr
----- Original Message -----
From <Daniel1312 at aol.com>
To: <spridgets@autox.team.net>
Sent: Sunday, July 09, 2000 10:49 AM
Subject: Zenith-Stromberg carbs
> Hi List,
>
> What is wrong with the Zenith-Stromberg carb fitted to the 1500 Midget?
Is
> it too small, non adjustable or non parts (diaphragm) availability that
> resign it to the scrap heap?
>
> Thanks
>
> Daniel1312
>
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