Have you checked the height of the floats? It sounds like they may be
adjusted such that flow to the bowl is not cut off when full.
> -----Original Message-----
> From: owner-tigers@autox.team.net [mailto:owner-tigers@autox.team.net]On
> Behalf Of Flüeler Roland, FLO
> Sent: Tuesday, May 25, 1999 4:10 AM
> To: 'tigers@autox.team.net'
> Subject: My carb - the "overrich" and unadjustable
>
>
> Folks, your mechanical wisdom is required here. That I am at a loss with
> explanations doesn't bother me - the work on the carb being the first
> serious thing on a mechanical part of my Mk I - but that my mechanic who
> works on all the Tigers in our club is also helpless makes me
> worry. What's
> the matter?
>
> After having detected a leaking seal on the accelarting pump I
> decided that
> it was time that I made a start in getting to know my car a bit
> closer. So I
> ordererd a carburator overhauling set and ventured to replace the
> seals etc.
> on my own. It all worked well (seemingly): I took the carb horn
> and the main
> body off, cleaned all the parts, replaced the old power valve (I didn't
> replace the fuel inlet needle though and I left the throttle
> plates and the
> throttle shaft untouched), put new seals in and fixed everything
> again. Now
> the big question: Would it start again? Indeed it did. However I had
> problems when adjusting the idle speed. The rpm would raise and go down
> again, all being unstable. Moreover the mixture obviously was rich, very
> rich to say the least. Black smoke from the exhaust! After
> fiddling a bit on
> the idle adjusting needles which showed little effect I was still not much
> embarrassed: Well that's a mechanics job then, I said to myself
> and took the
> car to him.
>
> I am embarrassed now: We couldn't do the job. We tried
> "everything" (that's
> what one always thinks). The amazing discovery: Even with the
> idle adjusting
> needles fully turned in the engine was still running with black smoke and
> with an amount of CO twice as high as normal. The needles are not worn.
> They're o.k. But turning them has no effect at all. We tried
> different fuel
> levels, starting from the "official" one, all to no avail. May be
> that with
> a ridicully low fuel level the rpm was more stable but still the
> mixture was
> EXTREMELY RICH. The fuel inlet needle works fine. The carb
> doesn't overflow.
> The accelerating pump works also fine, the seal is tight, the
> engine reacts
> quickly on acceleration. So the thing which caused me to start the job is
> o.k.. All holes or passages seem to be clean. In fact too clean perhaps,
> because through some - unknown - passage the excess fuel must
> come. What is
> also different as compared with the situation prior to me working on the
> carb. Formerly I didn't hear the fuel pump when it was at work. I
> only heard
> it "click" when it filled the fuel bowl prior to starting the engine. Now
> one hears the pump "clicking" even while the engine is running. May be a
> sign for the great amount of fuel which passes through the carb right now,
> but in itself not alarming probably.
>
> Does anyone have an idea what the cause for this "overrich" mixture could
> be? Or: May be that you can give me an indication as to how I could detect
> the failure more systematically than just taking all apart once more?
>
> Thanks a lot!
>
> Roland
> B 9471941
> in Switzerland
> e-mail: roland.flueeler@cantrade.ch
>
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