Hi Phil , When adjusting Carb's and Idle speed etc you really NEED a set of Carb Syncronizing gauges . These will allow you to adjust each carb and sync them to the manifold vacuum . They do have an idle screw but by adjusting this you will need to adjust the carb's . You could EASILY drop the idle on it with the screw but it will probably run like a BAG of BOLT'S , Not idle smoothly . Have you got the seriial number . cheers