Neil..........
A couple of thoughts occur.........
First, when cold, the car should start and die as soon as you let the choke
go! If it will run when cold without choke, then the mixture is set too rich
when the engine is warm. The twelve-flat down initial setting should -
coincidentally - put the tops of the jets in the position that the manual
says. But as Bruce said, that is a starting position and you may find you
have to adjust from there a few flats in either direction to get the perfect
idle when the engine is fully warmed up.
(Bruce's 20-22 flats suggests to me either that he has the wrong needles
fitted or his float levels are set way too low.)
As to the difficulty of operation the choke, are you sure you connected the
linkage properly? The link actually goes on the "wrong" side of the jet, in
that the screw comes in from the float bowl side. It looks awkward and is
hard to connect but, if you attach the link the other side, the angles make
for a really hard pull. You should fit one return spring to each choke,
attaching the other ends to the closest tang on the heat shield. The cable
run comes from the dash to the abutment on the linkage bar, then the inner
cable is fixed to a cable stop in the horseshoe clamp that secures the
forward air cleaner. If your cable goes any way other than this, it will
result in a hard pull.
(Other listers note this applies only to the HS carbs on an MGB; HIFs and Hs
are choked differently.)
Hope this helps!
Lawrie
-----Original Message-----
From: Neil Cotty <neilc@tradesrv.com.au>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: Sunday, November 29, 1998 5:04 AM
Subject: Choke Linkage
>Hi all,
>
>These carbs are driving me nuts but I'll fix 'em yet. I managed to hook
>them all up, fixed the binding throttle linkage (durr the arms on the
>linkage were too tight causing the shaft to bind, and I thought this
>wasn't the problem!) and also the fuel pump still pumping issue - thanks
>to Gary with the 75 Midget. Because the carbs were empty, the fuel pump
>had to pump a lot more fuel than usual to fill the empty chambers, and
>it seems it pumped some debris up to the float chambers which blocked
>the needle - even though I have a fuel filter on the line. Well after
>disconnecting the overflow pipe from each float chamber and finding out
>it was the front one still pumping fuel, I gave the chamber a few taps
>with a screwdriver handle and whammo stopped immediately! Thanks Gary!
>:)
>
>I now have another issue to solve but I should be able to fix it, just
>thought I'd bring it up on the list. In Lawrie's video he brings the Jet
>adjusting nut down 12 flats for the starting position on the HS4's. My
>carbs would not run in this position. Why I don't know, maybe I stuffed
>up. The mixture was way too lean as I found out by actuating the choke
>linkage - the car started, but died when I released the linkage. I got
>very tired and decided to call it quits for the day. I also have to
>readjust my timing as it's way off even after I thought I got the static
>timing right. Go figure. Adjusting the dizzy is a major pain in the
>backside, getting at those bolts is almost impossible if you've got huge
>hands like mine. I wonder if there's a special tool available or a tiny
>spanner. Anyways, I read the SU factory manual and it seems they suggest
>taking the dashpots off and adjusting the jet until it's level with the
>bridge of the carb and this is the starting position. I'll have a look
>tomorrow and see if this works.
>
>To the choke issue - I really can't get this to work. My choke linkage
>had one spring attached when I removed the carbs, the other one had
>broken and was left hanging from the heat shield. With my two new
>springs attached (same as the throttle springs) I *cannot* move the
>choke from within the car. With one attached I can just move it but not
>enough to lower the jets. I really need some advice on this one! Photo's
>of a similar setup would be wonderful as a reference. If I move the jets
>by hand with the choke linkage it is quite difficult to move, there is a
>lot of tension, but it does move and move smoothly. They appeared fine
>off the car - in fact they appear to be the same even on the car, just
>can't move them with the choke cable. Hmm!
>
>Finally I had a bit of a shock. The first time I ran the motor, switched
>her off, I had exhaust fumes pour from the exhaust manifold - centre
>pipe. New gasket. The second time I ran it this problem went away and
>hasn't occured since. I retightened all the bolts I could get at but I'm
>guessing this needed a bit of heat to bed in the first time as it hasn't
>happened since. God I don't want to have to take the whole #($*(#*@ lot
>off again! <G>
>
>Oh and don't worry I'll be shutting up for a while once this carb stuff
>is finished. <G> :))
>
>Cheers,
>Neil
>
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