Subject: LRO: Re: Zenith 361V

From: "C. Marin Faure" <[email-masked]>
Date: Mon, 14 May 2001 18:50:29 -0700

Date: Sun, 13 May 2001 10:26:59 -0600
From: "Ross Maylor" <[email-masked]>
Subject: LRO: Zenith 361V

>I just returned to the list and was wondering if there was a way to search
the archives other than weeding through every posting.
I am having trouble with my new zenith 361v carb that I installed to replace
the old one that was warn and leaking gas past the O ring. The new carb is
doing the same thing and no matter how big you make the O ring it still lets
to much gas through.  Some of the locals say this is a common problem with
Zenith quality. Is there a fix?

You will get 4,351 answers to your question, all saying the same thing.  The
problem with your Zenith (both of them) is NOT the 0-ring gasket, but the
fact that the body has warped.  The warp allows fuel to flow past the joint
gasket and down a passage where it isn't supposed to go.  The cure has been
described in detail many times here, and at least one person will post it
again for you, I'm sure.

Basically, you have to first heat treat the two carburetor halves, which
the manufacturer did not do for some reason (probably too busy enjoying
gammon and Guiness down at the local- can't blame them, really).  This
involves putting the carburetor halves in your kitchen oven for specified
times at specified temperatures.  Once this has been done, you "grind" the
mating surfaces of the carburetor halves flat using a piece of heavy plate
glass and the appropriate grit paper.  Then reassemble using a new gasket
set, and if you did all this correctly, no more problem.  There's an unused
passage some people say you should plug up with a bit of rubber (the
passage the fuel goes down when the body warps), but if you've done the
other stuff correctly, there's no need to plug this passage, although
there's no harm in doing so if you want to.  There's at leat one web site
that describes the process in detail, but I don't know the URL.

I had to figure all this out on my own back in the early 1970s.  I, too,
thought the problem was the O-ring, but I eventually discovered the problem
was the warp.  I didn't know about the heat treating thing, so I replaced
the carburetor, which worked for a few years, and then when it warped, too,
I switched to a Rochester.  The Rochester had more disadvantages than
advantages, so after a few years, I switched back to a new Zenith.  Either
luck, the carburetor god, the fact that the local ran out of gammon and
Guiness the day this carburetor was manufactured, or the custom-made clamp
I installed to put compression on the back of the carburetor has kept this
particular Zenith from warping for the last twenty years.  It has not
needed to be heat treated or ground flat.  At least, not yet.....

But the chances are 99.999999999 percent that your problem is the famous
Zenith Warp (they should name a dance after this thing), not the O-ring.

________________________
C. Marin Faure
  (original owner)
  1973 Land Rover Series III-88
  1991 Range Rover Vogue SE
   Seattle, WA