SU HS6 leak

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Clifford Pope
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SU HS6 leak

#1 Post by Clifford Pope » Wed Jul 12, 2017 7:51 am

I've just discovered that there is a leak from the plastic pipe from the front float chamber at the point where it joins the jet assembly.

What seals the pipe at this point - is it just a push-fit? The other end has a nut and gland, but the jet end nothing.
I notice Chris Witor sells only complete jet tubes with pipe ready installed - does that mean the pipe is sealed in manufacture and cannot be separated or replaced?

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Alec
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Re: SU HS6 leak

#2 Post by Alec » Wed Jul 12, 2017 9:13 pm

Hello Cliff,

yes thta's right, the tube is a part of the jet and is not replaceable or maintainable at that point.

Alec
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herald1360
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Re: SU HS6 leak

#3 Post by herald1360 » Wed Jul 12, 2017 9:31 pm

Hi Cliff
Yes you will need a new jet , probably worth replacing as a pair.

Hope this helps
Paul Barlow
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1974 2500TC French blue
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Clifford Pope
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Re: SU HS6 leak

#4 Post by Clifford Pope » Wed Jul 12, 2017 10:28 pm

They are the waxstat kind. Would it be better to get a pair of the ordinary jets plus the conversion kit?

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Re: SU HS6 leak

#5 Post by johnnydog » Sat Jul 15, 2017 11:14 pm

I would change the waxstats on your HS6's for the red tipped jets which seem to be more consistent in their mixture delivery.
Not done it myself, but I do believe there is a conversion kit available.
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Re: SU HS6 leak

#6 Post by tony » Sun Jul 16, 2017 6:13 am

All sorts of idea's here on the use of waxstats or not. Personally I refitted new one's to my S . Easier than changing everything over. Mine were badly worn and replacement fixed the problem for me.
Tony.
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Hopefully not needing too many bits.




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Hopefully don't need bits !

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Re: SU HS6 leak

#7 Post by Clifford Pope » Fri Jul 21, 2017 2:21 pm

After talking to Chris Witor I took his advice and just bought a new front waxstat jet.

The car started well, but even when warmed up idled very badly. Pulling the choke a bit made it run perfectly, so clearly a weak mixture. Specifically, pulling the new jet down a bit had the same effect, so I unscrewed the jet adjuster screw. It took 9 flats to achieve a nice even idle, and the engine would then rev up instantly and without hesitation on blipping the throttle. In addition it needed 1/4 turn faster idling screw adjustment to prevent stalling on sudden release.

But I was surprised at the large adjustment needed. I've been used to tinkering hitherto with one or two flats at most, so nine seems a very radical change. Something must be very different between the old and new jets.

Another thing I discovered was that the jets are quite reluctant to lift back to base on releasing the choke mechanism. Despite cleaning and a touch of oil on the coil springs, they are not quite strong enough to fully overcome the friction of moving the jets, so the car must previously have been running on an adjustment to counter a permanent touch of choke.
I have overcome this by fitting a bracket between the two carburetors, held by the nearest dashpot screws, with a pair of light tension springs hooked on the choke link rods. This entirely overcomes any tendency for the jets to stick.

Ideally I presume it now really needs a complete from-scratch retune from basic settings at the bridge, and individual trial with the lifting pins and balancing.

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