Thread: How to adjust the mixture on a 6 cyl series 3??

Is the carby a Stromberg? I seem to recall it is.
If so I think that vintage will have a nut ( on top of another nut. Only turn the outer nut) in the centre of the underneath of the carby. This is the main jet holder. You turn it in (clockwise) to lean the mixture.
If it doesn't have a nut you need a special tool to go down the dashpot and turn the needle holder.
Regards Philip A

If its the rover 2.6 ltr then be very careful leaning the mixture. These engines have a problem burning the exhaust valves in pistions No.5 and No.6 made worse by trying to save fuel.

Lean mixture = more heat = head job....... the bad sort :-)

Bruce.

Thanks for the tips, i'll have a look tomorrow. It's running pretty rich at the moment as it's blowing black smoke. 8O

Make sure the choke is fully open, the air filter isn't blocked or the fuel bowl isn't flooding. Simple yeah but you'd be surprised how many times it catches people out.

Also don't the stroms normally have a preset main jet ? Adjusting the mixture only is for the idle not throttle so adjusting it makes no difference to fuel consumption ?

Reason I ask is on my series 2A the main jet has an adjustable jet on the base of the fuel bowl which allows adjustment of the throttle mixture. There is another screw on the other side which sets idle mixture.

When tuning the carb, nothing is better than a bit of fuel hose jammed in the earhole with the other end down the carby throat. I do the twin dual throats on the Mazda using this method along with a vacuum float first to sync the butterflies. Wants to be a nice bubbly sorta gurgle at idle and a strong flow at revs.

The carby I have described is a Stromberg CD175. It is a sidedrasft carby with a round top.
If this is the one then the mainjet adjustment, or needle adjustment affects the mixture from idle through to but excepting full throttle.
If you are blowing black smoke, I would expect that the choke (enrichener, the CD175 does not have a choke butterfly) is leaking, The aircleaner is very blocked, or the needle and seat is worn out. Or maybe and more likely the diaphragm is leaking air. This is easily checked by undoing the four top screws and looking inside.

Fix it before you adjust it.
Disregard all this if the carby is a downdraft one.
It would help if you gave a clue as to the type of carby.
Regards Philip A