Is it worth adding a PCV like on the HP500's?
 

I have seen where Merc was running a PCV in the lifter valley, mounted in the intake manifold of the Dart intakes and routed up to a fitting on the carb spacer. Does this significantly help with blowby and excessive crankcase pressure? I have run breather tubes up to my flame arrester in the past, and have always had the annoyance of some oil dripping out of them. Wondering if the PCV will help with this. My manifold that I am going to run already has the boss for one - it would just be a matter of drilling the correct diameter hole and obtaining a grommet and PCV, etc.

What is a cross reference for the PN of the PCV that is used. Will a standard automotive one work? Diameter of the grommet? I guess I will also have to get a spacer with the right fitting in it.

If it is not worth doing, I guess I will just ditch the whole idea, but I figure Merc did it for a reason. Appreciate any feedback anyone can offer.

nice thing about PCV is you don't get blowby in cockpit at low speeds. but when on the power, you have no vacuum, so PCV isn't sucking. but bilge vents better at speed anyway. virtually all sport fish and other larger non-full-throttle boats have them.

dry sump them....no more oil leaks with added benefits.

Sorry couldn't help you on the heads deal my buddy at the machine shop is impossible to get in touch with now that racing season has started up. I like to run a breather on one valve cover and a PVC on the other to try to circulate fresh air in to the crankcase. Two breathers just let's air be stagnant. I had a motor that milked up oil with two breathers one time and switched to 1 breather and 1 PVC. Problem solved and I've been running that setup ever since.

I was going to do the same thing to my intake, my buddy's 525SC has the same set up in the back of the intake. I found a thread on here asking the same cross ref of the PCV the number they gave was CV856C
But I MUST caution you, you also have to run a valley pan or else the PCV will suck oil up. I ordered the pan from my local Chevy dealer. I still have to find a grommet that matches the PCV valve. Hope this helps.

GM part number for the oil shield is: 12555320