here we go this is the method I was tought by an old Datsun mechanic and it seems to work just about every time.


first make sure your throttle shafts are in good order if they are loose you will have a vacume leak and tuning will be almost impossible.


now to tune su's you will need the following: two hands, one flat blade screwdriver, a unisync, and about twenty minutes.

1. syncronization:
this is not where you use the unisync.
find the linkage that opens one carburator.
open the carb fully there is an adjuster screw between this carb and the other one. adjust this screw untill the carb not attatched to the throttle cable is just touching full open.
the carbs are now syncronized. you are not done yet...read on

2. idle syncronization:
this part is where you will need the unisync. look at the carbs there should be a screw on the side next to the throttle shaft this is your idle set screw. place the unisync over the rear carb and set the idle to about 650rpm note where the disc in the unisync is try to be precise. then go to the front carb and repeat if the disc is in the same position you are done with this step if not adjust untill it is. your idle should pick up a bit if it is out of sync.

3. fuel syncronization and setup:
this is where you need your hands. take a look at your carbs you should see a cap on the top of the carbs and a knob at the bottom of each now slide your finger up along side the chokelever you will feel a flat pin this raises the slide and disables the carb for a moment. start and warm the car. remove the caps from the top of each carb. now with the car idling reach under one carb and lift up on the pin the engine should drop two cylinders, repeat on the other carb. if it doesn't drop two lean out the opposite carb turning the knob counter clockwise. however if the engine dies, restart it and turn the knob clockwise to richen the mixture. repeat as many time as it takes to get it.

4. oil mysteries:
the oil you use in you su's is up to you hoever there is a bit of advice i can add. if you are primarily driving on the street use a good atf type oil. the oil is a shock absorber for your carbs slide if you use too thin of an oil the slide will slam up and down wearing the parts but if you yse too thick anoil the response will be too slow and it will act like the choke is on.

if you use these tips your su equipped 1200 should run smooth and get decent milage along with an increase in power(considdering that they were out before)

Good advice.....I've run twin SUs on my MGB for over 20 years with no probs. Most carb problems are caused by "experts" who don't know what they are doing. Over the years I've had cars running all sorts of carbs and personally I'm far more comfortable with them than tuning injection which I've done as well. SUs are good streetable carbs, but of course there are more powerful options but it all depends what you want from your car and engine. All you fellas have to remember the parts you are dealing with are all getting old and will be worn..30 years out of a throttle shaft bushing is pretty good for a start.