you can replace those o rings easy enough,i got some from the local bearing service,our nut and bolt shop has them aswell,if they leak and suck air itll lean out your mixtures,worst case overheat and seize,as well as crappy idleing,those little screws are where you connect a vacuum guage for syncronzing the carbs,when youve got the manifolds off ,if the screws project into the manifold at all file or grind them so they are flush
