^^^^ I am not trying to sound like azz here but ^^^^ I will bet you any amount of money in post # 18 part number 8 is a real working PCV in a Mercruiser stock set up app. I am giving out 2 to 1 odds any takers

http://www.ebay.com/itm/Mercruiser-N...-/200960287676

up to 3 to 1 odds

http://www.cpperformance.com/p-50660...8m2017060.aspx

No bet. Merc calls the plastic open fitting on the VC (that some mistake as a PCV) as a breather.

The one you are pinpointing is a PCV, which Merce refers to as a PCV.

The pic to your link shows #8 as a PCV (#8M2017060 VALVE, PCV $8.78), and #6 as a breather.(#97850T ELBOW, 90 Degree, Breather $3.71)

Anyway, as mentioned by others in the thread, a PCV will be hooked to vacuum, and a Crank Breather will be open to atmosphere, usually vented to flame arrestor.

Sure I agree - I never said the PVC valve is connected to flame arrester, Said some apps incorp both set ups inwhich can be common for Merc production stock apps. Just saying.

What I did basically mentioned is , have no idea why someone would spend all that time making a PCV into a breather valve when you can buy the breather valve in a 90 or straight app for a couple bucks.

Anyways was just showing that for whomever for info.

That’s just it Bup, you won’t find one at the local auto store and would have had to be ordered. I’ve been known to modify a few parts to make work. Like when I had a set of valve covers that had the oil fills open on both covers instead of an oil fill in one and the smaller hole in the other for a pcv. Had to use a chrome oil fill breather looking thing with a built in PCV valve inside. Then gutted the guts of the valve out and I was back in business. But that was a long time ago when I was a kid and had no money and a cool set of valve covers.
I have to say, even though we have been through this fight before on OSO, for about the last 30 years I’ve use PCV valves hooked up to the base of the carb on all my boat motors. Even my hydroplane that motor is completely open. It’s just cleaner.

Yeah, I'd have to say availability was why the would've been used. Merc would've required calling, waiting a few days etc. These you can get on any corner, any time.

Look at it this way:
IF the mechanics labor rate is say $100/ hr, it's going to take him $20 in labor (IF he can do all 4 PCV's in 12 minutes or less) to cut open an $8 PCV (x4). That means he's invested roughly $52 of YOUR dollars into modifying what could have been purchased for about $16 from OEM / Merc... Better in many ways to use the factory prescribed parts in this scenario.

I actually didn't notice if I was charged labor for customizing pcv valves. There was plenty of other bs labor charged though. Clearancing my old throttle brackets for more than what new ones cost. This wasn't really started as a beware thread though. I just wanted to warn people about the extra piece of metal if anyone ever does this. Based on him saying he commonly does this, I'm pretty sure there are other engines out there with this piece ready to drop into the valve cover.

Stupid quistion...what causes the detonation : the poorly vented valve cover or the crap vented into the carb via the hose to the air cleaner? Reason I ask? I just modified my valve covers. Had Edlebroc "tower" breathers blowing fumes into bilge/boat. Wanted to scavenge that crap and have it expelled out through the exhaust. Am I going to blow up?

Surprising how many people think PCV stands for Pollution Control Valve. :)