The flat top SU's don't have smog equipment as such, they just have a sort of tamper proof system for adjusting the mixture and idle. Most Datsun Service Manuals show the early round top SU's which don't have that system. I've got some scans of a service manual covering the flat tops on my website...

Flat top SU's

You can blank remove the pipework and the extensions they attach to on the carbs and fit blanking plates but that leaves you with no mixture adjustment as the jets are fixed. You can make those fixed jets into ajustable ones though. The adjusters are encased in a metal tube thing which can be removed with care.

You have to gring off the rivets as shown by the red arrow in the pic below then grip the tube where the green arrow is pointed with some vice grips and unscrew the tube. When you grip this bit you need to do it hard enough to clamp the tube down onto the collar inside (green arrow second pic below) so you can unscrew it. Once it's off you can chuck the tube and screw the collar back on. They are now adjustable same as old SU's. The solenion valve is just an anti dieseling valve so you can either leave it on or remove it..up to you. Sometimes they run on after turning the engine off if you take it off.







Not sure if the Aussie flat tops are the same as ours but the chances are they are the same.

-Ed