www.iFourWinns.com

Hi all,

I'm getting tired of cleaning nasty looking blowby from my flame arrestor and am concerned at the amount of moisture/ crap that comes out of my breathers.
My 1997 Volvo 5.7GLPLKR is the last of the flat tappet series of SBC's and has the TBI heads with a 2BBL carb.
My engine did not come with a PCV valve, but the next year model (Vortec) did.
I know of the great results by utilizing a PCV valve and am curious as to whether it's worth rigging one up?
Will mounting the PCV hose to the flame arrestor create sufficient vacuum for the system to proactively remove these fumes? I do not have a PCV port on my Holley's base plate.
Am I re-inventing the wheel?!

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2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

Sorry Mate, Dunno... But jees those exhaust headers/risers look good

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Cheers

Mark
Melbourne
Australia

Boats:
Current: 2004 FW 190
2001 Mastercraft X5
1998 Malibu Response
1999 Sea Ray 180
17 ft Scimitar Barefoot (200hp Yamaha)
16ft Scimitar Ski (Yamaha 115)
1988 Ski Nautique ( Called Ski Antique)

A PCV valve operates strictly by manifold vacuum, so I'd imagine that simply hooking up the existing hose to an automotive style PCV valve would do you no good. To do it right, you'd need to pipe a PCV valve stuck in the rocker cover on one side to manifold vacuum, then put in a breather on the opposite rocker cover. If you want to get real fancy and simple, perhaps the solution would be to rig up a "catch can" style oil separator to the existing vents in the rocker covers, then on to the flame arrestor as you have it now. If you have the room, a plastic coffee can would make a great catch can.

A catch can would reduce the crap on the flame arrestor, but wouldn't force the humid gases out of the engine, right?
Would it be worth buying a reco' base plate (with PCV port) to fit to my existing Holley 2300, or can I get vacuum from somewhere easier?

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2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

Yeah, the catch can just keeps MOST OF the crap off of the flame arrestor. As for the humid air being expunged, I don't think it would be too awful much more effective than what you already have. There's always sufficient blowby flowing, and it's being ingested into your engine intake whether you have PCV or not with our setups we have on marine engines. It has to go somewhere, after all, and putting it back into the engine has little effect on performance at the volumes we're talking about. If you really want to go with a PCV style, then I guess your easiest route would be a baseplate that already has the port. One could also drill and tap for a port (having to remove the mainfold), or change it to an automotive manifold that already has it.
Or "catch can" it as an experiment first for the price of a tin of coffee and some hoses, just to see if it cuts down on the crap we have to clean from the flame arrestor

Now I'm dating myself, but way back in time cars did not even have PVC valves (pre 1963).There was something called a road draft tube, which was a tube in the crankcase that relieved the pressure of blow by via air flow across the bottom of the tube. Then some one felt that this was a threat to life on earth do we got the PVC. Which if it sticks gives you a rough idle.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

my old marquis had the pvc ran to the arrestor, each valve cover had valves hose ran to a fitting riveted to the top plate of the arrestor. sierra has them but you could make the fittings yourself

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1989 245 vista
5.7 cobra

Hi Lou,

Technically speaking, my marine engine has a draft tube (X2) that vents to the flame arrestor.
A PCV valve is a one way check valve with a breather (filter) on the opposite rocker cover.
The PCV is ducted to manifold vacuum, which I'm assuming creates reasonable airflow throughout the crankcase.
From everything I've read, a PCV significantly reduces oil contamination from moisture and general acidic nasties from blowby, by proactively sucking them in to the combustion chambers...
My breather tubes are simply messy openings with hoses attached!

_________________
2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

True they did that because unlike an auto engine there is no real airflow across the ends of the tube, but there is suction from the flame arrestor. On cars the road draft tube stuck out of the block and went down into the airflow below the vehicle. My VW Beetle had one too. If it was plumbed properly there would be no problem with a PVC on a boat engine.
Believe it or not GM came up withe idea for the PVC, based on their production of tank engines during the war. A road draft tube would allow water to enter the engine, under certain conditions.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

One more thing while thinking about this, and that's the fact that our engines work harder than the average automobile engine, and that equates to more heat, more blowby, and less moisture in the crankcase from the combustion process. I imagine a fair amount of moisture can enter an automobile engine upon deceleration, but since our engines never decelerate, per-se, that's less of a problem. I've torn apart 3 or 4 high-hour marine engines for rebuild in the past, and I've never seen issues with sludge, corrosion, or any of those nasties I've often found in automotive engines. Heck, I can't even remember the last time I've changed oil in a boat where the oil was anywhere close to as black as a typical automotive service interval, even when going on a two-year cycle.
I may try the catch can option myself simply for the reason of getting tired of cleaning the oily gunk from time to time. There will still be residue, just not as much.

Thanks for the technical advice, fellas.
If I were to rig up a basic 2 port catch can with a breather filter on top, would this suffice, or do I still need a return to the flame arrestor (3 port catch can)?
I'm assuming I'll get a minor oil vapour smell while using a catch can?

_________________
2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

I'd still do my best to keep a return running to the flame arrestor. That way you won't get any smell of blowby.
Many people use copper wool as packing in a catch can. Not sure if you can get it down yonder, but up here we have kitchen scrubbing pads that are basically wadded up long copper shavings. If you stuff the can with that, it gives lots of places for the oil to condense upon so that hopefully very little if any vapors that reach the flame arrestor will have oil fog in it.

Thanks again for the advice!

I'll order a dual entry, baffled catch can & try it with the top mounted filter.
If I find the oil smells too obnoxious, I'll plumb the filter port back to the flame arrestor.
Now, where to mount this bad boy?!

http://www.ebay.com.au/itm/171128721361 ... 1423.l2649

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2011 Four Winns H180 SS.
Aussie built Mustang 2800.
SOLD - 1997 Four Winns Horizon RS

That's real pretty, and a great way to do it. Good luck! I'm interested to see how she works out!