A well balanced motor with a stock carby is a dirty pig.
On the same engine. a couple of DCOEs will screw with your fuel economy..but make you smile.

If a factory decides that twin SUs make a difference...it's speaking volumes. A factory mod is a measurable modification...otherwise they wouldnt do it. Save 5 dollars on one car..save 5 million on their run...not something to sniff at.

I think your wasting your time with Side draughts (aka webers, dellortoes and Su's etc) on bog stock motor, there is not enough gain to warrant this extra fuel with no improvments to the motor.

You are best spending your moeny on the motor improvements such things as Cam, head work, extractors, some bottom end work etc...these all lead to a more improved motor in terms of Flow, HP and RPM. THen a set of side draughts would be warrented to provide the fuel, better revabilty and greater performance. You would see a marked improvement from sidedraughts on a motor that is built for them. Look at the Aseries the motors with factory side daughts were on the more improved motor SSS / GX.

I am also pretty sure that a bog stock Aseries will not even run with twin carbies, the cam is not large enough.. maybe SU's tuned down alot but not Webers, could i be wrong?

The amount of carbies and what type of carbies also depend on the motors CC's of course.

Other factors come into play with turbo and superchargers.

But dont be put off, side draught carbies are a hell of alot of fun with the right motor!!!

Define "side draughts" as you understand them to be.
Any method of providing a greater volume of fuel /air mixture to the cylinders, in the correct ratio, will result in increased performance.

Induction systems with a horizontal airflow manage to do away with right angle bends which are seen by many as an impediment to the airflow at high engine speeds, so as long as any side draught induction that you may use is correctly sized to your engines airflow requirements, & correctly callibrated for mixture control, then you will gain an improvement in maximum engine output.

Do side draughts really make sutch a big diffrence on a stock 1400 motor as sum ppl say?

Plz guys help ;P