SU HS6 Needle ID

[Robin]

How easy / difficult is it to identify the type of needles used in twin HS6 carbs? If I manage to get the needles out do the carbs have to be re-tuned again once I put them back?

 

Thanks

[Clive]

the code is stamped on them. You need to take the piston out the dashpot, undo the needle retaining screw, and carefully get the needle out along with the holder. Stamped up at the top. No, carbs wont need retuning after as long as you put it back together the same.

[Robin]

the code is stamped on them. You need to take the piston out the dashpot, undo the needle retaining screw, and carefully get the needle out along with the holder. Stamped up at the top. No, carbs wont need retuning after as long as you put it back together the same.

Thanks Clive - I'm taking the car to a rolling road in a few weeks time and they've asked what needles I've got.

[Robin]

 

 

Checked the needles and they're stamped BAE.

 

The engine is a standard unit from a 2000 mk 2. It runs well but a little lumpy on tick over (better when warm) but I'm only getting about 170 miles on a full tank (was getting just over 200 miles when I had the Stromberg 150s). Could the low consumption be due to the needles and if so what type of needles would be better?

 

Going for a rolling road session at Revivals soon so wondering if I should change the needles now or wait until I see what the rolling road reveals.

 

Any advice would be welcome

 

Thanks

[MickW]

Hi Robin,

 

I would leave well alone if you have a rolling road booked you will just be guessing even if you use minty lambs excellent charts. If you ring Burlins technical department they will advise on everything except needle selection, it is only on a rolling road that final selection can be made. I would expect Hs6s to be less economic the CD150 as they have a 1/4 inch larger choke, indeed they are fitted to increase fuel flow hence lower MPG. So if the car will get to the road leave it alone!

 

Mick

[Clive]

Part of the issue is that the carbs are really too big for the engine. Put your foot down a bit, and more air will enter the engine. Therefore more fuel required.....Smaller bore carbs will give better throttle response, only losing out at high RPM, 

[Robin]

Hi Mick & Clive

 

Thanks for the advice - I think I'm going to swap back to the strombergs before the rolling road. Switching to SUs has been an expensive experiment but I guess it's all part of the learning process!