1984 6 HP Johnson<br /><br />While rebuilding above motor, I noticed that the carb throat I.D. measures .810 , while the intake manifold measures .750. The manifold opening is not centered between the mounting bolts, it is drilled lower than the centerline between the mounting bolts.<br />Since the manifold was off the block, I slid the carb into a mounted position on the bolts and looked at the assembly from the intake side. I noticed that only the bottom edges of their respective openings are congruent. I'll assume that this was done by design to prevent puddling of fuel in the carb throat, correct me if I'm way off base here. Since I'm in a guessing mood here, I'll assume that the manifold opening is not the same size as the carb throat to restrict the fuel mixture to limit HP. I hadn't noticed the mismatch (if there was one) in other motors I've worked on. Is it normal (in a stock engine) to have this mismatch in size between the carb throat and the intake manifold?? <br /><br />I'm aware that some folks believed that all that was necessary to change the high speed jet on a 9.9 and get 15HP performance seldom worked because the carb throats are different sizes in the 2 carbs. Based on that fact, it seems reasonable to expect the HP to be less if the intake manifold opening is undersized as well.<br /><br /> What's the poop?? 
