Those older systems do have a slight advantage over the VC in VC out systems. Do a few high rpm blasts and get the valve covers a bit full of oil, don't have to worry about ingesting oil or clogging the breather with oil. There are a lot more pushrod holes to the lifter valley than there are drain holes to the crank case. More likely to have more air just getting blown across the lifter valley than down the oil drains, through the oil, pan and up through the oil drains in the heads. Modern engines have several PCV passages built into the engine and covers to better evacuate vapors and provide fresh air. PCV systems in older vehicles sorta worked, but were lacking with single point entry and exit systems. Are you just looking for a cover for the 'ugliness' of the PCV valve? Spectre 4284 is a cover that uses the PCV valve as its base, very simple design. Gives the twin breather look while being a PCV system. It uses a standard 3/4" PCV valve and the cover just sits on it and has a nipple to attach the hose to. Have used them to eliminate the PCV 'ugly'. If you are good at fabricating you can modify one of two breathers and make it work if you are looking for a specific look.
More holes means less suction pressure. This is my logic anyway. None of us have any actual empirical data to prove wither way which is more effective. This is not to suggest that anyone is more or less correct than I am it is just my way of saying that I have no way to prove my theory.
I'm fine with the appearance. I had an issue with the Dart valve covers, the gaskets sucked in on the ends and I had a good oil leak going on. The gaskets are Moroso (not cheap) and I glued them to the valve covers. I have billet ones on now that have a channel for the gasket. I still think I need more venting than I have. I get an oil smell too often. Not burning, just smells like raw oil and I have oil leaks I'm eliminating. The engine is fresh with 10k miles on it.. and yes, it goes like a scalded tomcat. I ran the stock cars with 2 breathers on the driver-side valve cover, no PCV valve. I can go with 2 breathers alone and see what happens.
Thanks, that makes sense. I thought I have seen a breather that takes a PCV valve. I drop the oil and filter once a year anyway at 3000 miles. The oil has always been clean. So two breathers may work, or the one I have doesn't breathe as well as I think it does.
There are "breathers" that take a PCV valve, but they don't have any other openings, so they aren't really breathers.
If it pisses people off... count me as in. Makes going to work worthwhile. If I could find a front-sump oil pan for a BBC, I'd take it to the next level.
I've posted this little diagram before but I thought it might be helpful so here it is again. (I keep a digital file folder where I save al these types of visual aids.)
I looked at some, a Stant 10078, no real advantage there. Ford used to have one for the 390 that took a PCV valve and it drew air from the bottom, but that is for the old style valve cover and won't fit mine, Stant 10071 is similar. I could get one like the Stant 10078 and drill holes on the bottom, a bunch of 3/16" holes but I don't know what is inside of it and I could be letting in dirt. I could add another breather but I need to add a baffle to it. The valve covers are tall aluminum and I'm sure I have the rom, but like you said the flow would take the path of least resistance. I have no qualms about cutting up an expensive pair of valve covers.
Does a 2 carb system on a flathead Ford require a Y (split) shaped hose where both carbs run off the same common(1) pcv?
The Jalopy Journal
