• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Which way to turn the SU jet adjusting nuts?

Share this page

wkilleffer

wkilleffer

Jedi Knight
Country flag
Offline
Hello,

After driving a couple of days with my newly adjusted and balanced carbs, I think that they might need to be adjusted for a slightly richer mixture.

This throws me off every time, but which way do I turn the jet adjusting nuts? Clockwise or anti-clockwise to richen? Or, toward the firewall or radiator? I'm looking down on them from the left side of the car.

Thank you,
 
Screw em out for richer, in for leaner. Just like any old bolt.

Out backs the seat away from the needle, ie richer.
 
clockwise to lean if you were looking at the bolt from under the car.

or if you are standing facing the carb and have a wrench on the side of the nut closest to you you'd turn it to the right to lean.... left to richen.
 
And here's three nice pages on SU adjustment.

https://www.teglerizer.com/sucarbs/techtip6.htm

https://www.mgcars.org.uk/cgi-bin/gen5?runprog=mgoc&p=emg/basic4.html

https://www.teglerizer.com/sucarbs/garrettech.html

Generally, screw the jet adjusting nuts all the way "in" and then unscrew 2 full turns (or "12 flats" as they say in the SU manuals).
Be sure that the mixture needle is not too far into the damper piston....the non-tapered part of the needle (the "shoulder") should be even with the lowest part of the piston.
 
Back
Top