spridgets
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Re: Carburetor troubles

To: Bill Gilroy <w.gilroy@verizon.net>
Subject: Re: Carburetor troubles
Date: Tue, 16 Oct 2001 06:52:15 -0500 (CDT)
Cc: spridgets@autox.team.net
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Bill -

There shouldn't be that much difference between the carb settings.  It
sounds like the front carb is "carrying" the back carb.  Check out
this link, where I've dumped about everything my Dad taught me about
getting a dual SU set-up running right.

http://members.core.com/~ckotting/tuning.html

There are a lot of possibilities, including the wrong needles or a
major air leak, but go through the whole thing methodically before you
get radical.  I've got the same set-up, so get back to me if the info
in the link doesn't get you where you want to be.

Chris K.
'77 Midget 1500 with dual HS4s

> I am still having problems adjusting my carburetors.  My car is a 77
> Midget with a 1500cc spitfire engine.  I have replaced the original
ZS
> carburetor with twin SU4, ala UK specification.
>
> The front carburetor seems to be adjusted about right.  I lift the
> piston with the lifting pin and the idle speeds up briefly and then
> returns to close to normal.  This carburetor is adjusted about 14-15
> flats out.
>
> The back carburetor is the problem.  I lift the lifting pin and the
> engine wants to die.  That is with the carburetor adjusted 12 flats
> out.  I have borrowed a CO tester in an effort to better understand
> what is the problem.  With the carburetor at 12 flats out, the CO
meter
> reads about 2%.  I continue to back the jet out and get to about 18-
20
> flats.  The CO meter goes to 8.5% and when I lift the lifting pin
the
> engine still wants to die.  The engine speed never increase and if I
> leave the pin up the engine will die.  Any idea what is going on
with
> my engine.  The CO reading says the carburetor is running rich, the
> lifting pin says it is running lean.  Something is wrong but I am
> stumped.  Both carburetors are new and in good shape and I believe
the
> reading on the CO meter.  Any ideas or pointers?
>
> --
> Later,
>  Bill                          mailto:w.gilroy@verizon.net
>
> 77 Midget



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