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Re: [Mgs] anemic running B

To: "1971-red-mgb" <1971mgb@cox.net>, "MG LIST" <mgs@autox.team.net>
Subject: Re: [Mgs] anemic running B
From: "Paul Hunt" <paul.hunt1@blueyonder.co.uk>
Date: Mon, 5 Nov 2007 13:09:36 -0000
OK, so the problem started when changing from HIFs to HSs.  HSs are 
marginally preferable from an owners point of view, and you should get the 
same performance out of both.  After everything else make sure you set the 
throttle cable correctly.  When released there should be a little bit of 
slack in the cable so the butterflies aren't hanging on it but are resting 
on the idle screws.  You must also be able to get full butterfly travel 
using the pedal, but the pedal stop on the toe-board must stop the pedal 
just as the carbs reach fully open so the cable isn't stretched.  These are 
achieved by a combination of adjusting the inner cable clamp at the carbs 
and the pedal back-stop bolt.  Also check that the pistons are free to rise 
and fall and don't rub on the piston cover or anything else.  The correct 
way to check this is by a 'drop test' - see here 
http://www.jcna.com/library/tech/tech0006.html.

Check the dampers with the engine running, air cleaners removed, open the 
throttle sharply and check both pistons rise together and are retarded by 
the damper, but drop smartly back down again when the throttle is closed.

If you have fixed needles check the piston drops back down onto the bridge 
with a metallic click, do this with the jet raised at least one turn so you 
know it will still be free with the jets down in their correct positions 
(different needles noted).

Check for vacuum leaks round the manifold joints with carb cleaner or 
preferably propane gas.

PaulH.

----- Original Message ----- 
> Paul, I've driven this car as a daily driver for the past 14 years, and
> thought the car was running strong till I changed carburetors ( ease of
> working on t the carb's if needed prompted that change) and it's just lack
> of power, I'll change back over to my old carburetors today and see what
> happens,
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