View Full Version : SU Carb Needle Selection

01-16-2005, 12:47 AM
Hoping someone might have some knowledge or experience in SU Carb Needle selection for a 1500cc Spitfire engine using mostly stock components except for headers. The carb is a HIF-6 SU Carb.

The primary reason I went to the HIF-6 setup was that I had major problems with the ZS carb choke assembly leaking fuel and found a header/HIF-6 setup for $55, a lot cheaper then replacing the auto choke assembly on the Zenith for $200 from MOSS.

My gut impression is to try a "BAS" since I found 1 referrence to a Austin Maxi 1500 running a HS6 with that needle. That's the close thing I can find. One person who is "An expert" told me however to use a "BEL" first which is significantly different that anything I can find.

Any suggestions would be much appreciated?


01-16-2005, 08:49 AM
Hello Thor,

here is a link to a S.U. needle selection programme. It is, however, at best a good guide and final selection really needs a dynamometer test of some sort.


Good luck.


01-16-2005, 06:10 PM
Hi Thor,
Having just completed a total restomod 641/2 Mustang, my first tune up manuver was to check the carb jetting. I have a tuner shop nearby and took advantage of having the car run on their dyne. This revealed a few enlighting corrective action items regarding the carb settings and timing. Being an owner of an early Etype with 3 HD8s, I know what you're going through. Most of these needle swaps and adjustments are experimental without, first establishing a baseline to serve as a starting point. Recommendations may offer ensight, but as each engine can be different, due to wear, timing, etc, my advice is to leav the headers on there, set the timing to stock, leave the needles alone, then find a tuner with a dyno. The $150 is well spent to get the baseline data. The dyno will provide the AFR data needed to determine where the corrections needs to take place in the RPM band.
Hope this helps!

641/2 Mustang Cvt
'67 EType 2+2
2004 XJR

Dave Russell
01-22-2005, 03:06 AM
Hi Thor,
If you don't want to down load software, you can go here to compare needles: