I volunteered to clean the carbs on my uncle's 150 Black Max. It's either a 78' or 79', but it is a V6. It hasn't been done in 5+ years. He tried to crank it this week on fresh fuel and it was a no go. Gas wasn't even making it the float bowl on the center carb when squeezing primer bulb. I have recently rebuilt the carbs on my 89' OMC V4 (piece of cake). I hope that they are somewhat similar. Do these mercury carbs have fixed orifices? Can they be soaked w/o worry? Anything special I should be aware of? I'll look for some literature at the library.