View Full Version : TR6 su carbs TR6

12-28-2002, 12:16 AM
just installed HS6 on TR6,new from Moss in England.no instuctions had to make linkage etc. anyhow,seems jets have to be lowered quite a bit to get proper mix,confirmed by colortune,this then pushes thechoke linkage downward raising the idle speed,as the coke link is connected to the jet, as choke is activated jet is lowered.....min speed 1000 rpms....would like to have lower idle speed..anyone know the correct needle jet combination.... confusion on needle placement in piston..as it is spring loaded and has some adjustment....holder flush with piston or all the way up or down...manual says flush..that places the needle down..and jet down to get proper mix....any help on set up of Su would be a great help....thanks jwc

12-28-2002, 04:25 AM
Hello JWC,

The jet shoulder should be flush with the piston face, this is true whether spring loaded or not.
The spring bias should be in line with the choke axis, either facing the throttle disc or the air cleaner. Nominal jet setting is twelve flats down from flush with the bridge, that is two full turns of the mixture nut. This is true for whatever needle is fitted as all needles have the same idle dimension. You refer to an idle speed of 1,000 rpm, is this with choke or without? Normally the throttle screw will allow a much lower idle speed when the choke is off. Set up the carbs with the link between the two slackened off to get an equal airflow at idle then adjust the idle speed and recheck the airflow until both are balanced and at the required idle speed. Then
tighten the connecting linkage.
Hope this is of some help.

Alec graemlins/thirsty.gif

[ 12-28-2002: Message edited by: piman ]</p>

12-29-2002, 08:58 PM
When you set up an SU, with the dash pot off, look down at the main jet. If the float level is ,the fuel level is at the top of the jet when the jet is appx.100in below the level of the jet housing. You're likely to need different needles to get the corect mixtures needed by the 6 cyl as the 4cyl needs are different. experiment with raising the needle in increments of .020in and see if you can get it close enough to get good readings on the road.
Good luck
MD(mad dog)

Gary Pope
01-10-2003, 11:31 AM
Moving the distributer can alter the idle speed dramatically. You should be able to idle at 850rpm no problem. I have HS6's on my 6 albeit old knackered ones off a Volvo. My jets have to sit way down to get the right mix and I have the so called rich needles. I have found that the TR6 won't run well at the recommended dwell angle. Most people have 12 deg BTDC but mine seams to run best at around 20 deg BTDC. In my case the Vacuum advance doesnt work on the distrib, so I am probably compensating for the advance curve.
I have never had much luck with the colortune either, its hard to see the flame and hard to tell what color it is, after 10 minutes the engine is starting to overheat with idling so long. I am really starting to think that a O2 sensor and air/fuel mix guage is going to be the best solution.