William -
In terms of the "no choke when cold, choke when hot" part of your idea, I
can't see how that's possible. The heat mass (the part that has the
bimetallic spring) only goes on one way, so unless the spring in the heat
mass was mangled, that's not likely to be it. Some "mistakes on assembly"
possibilities exist, however that you should check out: (Note, I'm doing
this from memory, so I could be a bit farmisht.)
1) The fast idle cam and/or the pivot piece that connects the bimetallic
spring on the heat mass with the vacuum pull-off and the choke needle were
assembled incorrectly. Possibilities: (a) fast idle cam installed wrong
way around (so RPMs increase as engine warms), (b) pivot piece misses
connecting with the choke needle or the vacuum pull-off. (c) fast idle cam
is jammed against a protrusion in the choke housing, so it doesn't follow
the choke mechanism. I've done all three of these at one time or another,
and this sounds like the culprit to me.
2) The spring in the vacuum pull-off was installed the wrong way, or not
installed at all. The spring goes UNDER the piston, so that if you remove
the heat mass, it pulls the choke ON. I've done this one too. Since you
assumed that the vacuum pull-off wasn't user-serviceable, this may be
unlikely, but who knows what a PO has done?
3) When you mounted the heat mass, you didn't get the loop in the
bimetallic spring around the tang that actuates the choke. This would
result in either too little choke (if the loop was behind the tang) or too
much (if the loop was in front). This doesn't seem likely to be the
problem, but it's worth checking.
The needle and the vacuum pull-off ARE user-serviceable, and all the
necessary gaskets and o-rings are included in the ZS carb rebuild kit (at
least the one I got...).
When in doubt, check the University Motors Tech pages on the Zenith
Strombergs, and ZS automatic choke.
http://www.universitymotorsltd.com/tech/tech041.htm and http://www.unive
rsitymotorsltd.com/tech/tech042.htm
I would not go the Weber route, unless you were making a number of other
modifications to the engine. A Zenith manual choke conversion can be had
for about $75, or a generic one can be tweaked to fit for about $14. (I
did that on mine for a while, and just converted back over to the automatic
choke. I'm going to use the dash-mounted pullknob to actuate the heater
valve.)
Chris Kotting
ckotting@iwaynet.net
'77 Midget (Drove it to work this morning, and it was just nippy enough
outside to want a little warmth.)
On Wednesday, August 12, 1998 9:58 AM, William M. Gilroy
[SMTP:wmgilroy@lucent.com] wrote:
> I have a 1977 Midget with a Zenith Stromberg (ZS) carburetor and an
automatic
> water choke. The carburetor was rebuilt but I still have the following
> problems:
>
> 1. Car will not start without start fluid
> 2. The one time it did start it idled rough and wanted to stall. Once
> it was warm it idled at about 2100 RPM.
>
<SNIP>
> Any help, tips, pointers would be appreciated.
>
> --
> William M. Gilroy
> 77 Midget, which I thought would be on the road this week :-(
> E-mail: wmgilroy@lucent.com
> Telephone: 732-957-4775
> Fax: 732-957-4775
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