I'm not sure what the numbers you found mean. However, I would suggest that you
confirm that the pistons move smoothly in the dashpots. With the air cleaners
off, you can use your finger to raise the pistons up. They should move smoothly
with just the slightest (but even) resistance. When released, they should drop
back down quickly.
If they pass that test then you could check that the needles are the correct
number (there should be a number stamped on them) and installed correctly (some
SU's have the needles inserted fully seated, some need to have the shouldered
portion set even with the bottom of the piston.
HTH,
Eric Russell
> Date: Fri, 30 Jun 2006 13:56:54 +0000
> From: wkilleffer@comcast.net
> Subject: HS4 SU carbs, question about numbers on their bodies
>
> Hello,
>
> I'm trying to adjust and balance the HS4 SU carbs I have installed on the
> 18GK engine of my 1974 MGB. The carbs have been rebushed and reshafted within
> the last four years, and don't appear to have any physical defects.
> Appearances can be deceiving, and I find that trying to do these adjustments
> is a major source of frustration, even with the right tools, the valves
> properly adjusted, and the ignition in fine fettle.
>
> I've tried switching dashpots and pistons around thinking that they might
> have been switched at some time in the past, and it doesn't seem to make a
> difference.
>
> I might have found part of what could be making this frustrating. On the carb
> bodies that attach to the manifold, there is a number stamped which is
> usually covered up by the piston. One carb says AUC 1300 in big digits, and
> the other says AUC 1384 in smaller digits and in a slightly different
> location. Could I be dealing with a mismatched set? Is a mismatched set a big
> problem? Any advice and suggestions would be appreciated.
>
> Thank you,
> - -William Killeffer
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