Interesting Wiki page on it. https://en.wikipedia.org/wiki/Crankc...ilation_system
That little stupid $3.50 valve cut vehicle smog emissions by half. At that rate for another $7.00 the only thing that should come out of the tail pipes is cotton candy and warm oxygen.

PS if it take your guy and hour to take apart 2 PCV valves you may need a faster mechanic.

So what exactly is the purpose of the PCV valves on the newer HP 500 intakes? I'm running that set-up on my HP 450 clones and I never understood why they added these.

because the epa is mandating it.the free ride for marine engines is over,most now come with cats.i think all under 500 hp are required to have cats.it,s a proven fact that a pcv system lowers emissions.

And in 2 years you will need 2 scan tools for these emission control MARINE engines. You will need a OBD II scan tool plus the lastest greatest Diacom or CDS. Year models 2018 starts the EPA / OEM marine standardization and then for the outboards when they get CATS. Huge changes are coming soon.

So those are there for emissions? Interesting! I know my buddy's new Master Craft X55 has the 7.4 Ilmor,which has 540 hp and his engine has cats. I won't be buying a new boat anytime soon, so i guess all I need to worry about are my two PCV valves.

Ya I guess my stuff will be grandfathered in being its as old as a grandfather. High tech in my world is an electric choke.

Yes, PCV's are for emissions, however, they also help greatly with getting humidity out of the oil.

or in simpler terms,,condensation in engine gets removed.less milky oil.

Yes, better wording. I'm currently in distress. I am being fitted into a straight jacket right now.

So what exactly is the difference between running real pcvs to the intake and just hoses to the flame arrestor? I can see how pcvs have a strong vacuum actually sucking fumes out of the engine. What do the flame arrestor ones do? Just suck in what the engines push out? Doesn't seem like there's much sense to them.