The reason I ask is because I'm running some vintage Cal-Customs vavle covers. They're finned aluminum, thick flanges, and they really turn heads like chrome just can't do, so I really don't want to get rid of them, but they have no baffles in the breather holes. I'm using about a quart every 500 miles, with brand new valve stem seals on new heads, with a brand new (8000 miles on the clock) engine. The only thing I can think of is that this oil is getting sucked into the PCV valve and consumed by the carb. I'm also using a high volume oil pump, so there's a great deal of oil in the top of the engine always, but no leaks.

By the way, I'm still rocking an Edelbrock 600 cfm carb (#1406)

So today I plugged the pcv in the valve cover, and on the carb, figuring that the breather on the other side could do all the breathing the engine needs. After starting it back up, the idle speed and qaulity dropped, so I tuned it again. I went about 3/4 turn leaner on both idle circuits, and got the speed back, and the vacuum is higher now that it ever was (22.5" at idle, steady as a rock, vs. 21" with a slight twitch of the gage). tell me now, what's the deal with having a PCV system as opposed to just an open breather? Apparently I don't have a lot of blow-by, because the only time the breather lets out any vapors is when I revv it up, then I get a little puff of white smoke out the breather. Rage, 'Fenders, 'Moose, Franklin, Ron, anybody have any ideas? Of course all not mentioned are welcomed to jump in as well, I am stumped here, none of my manuals say anything about removing the PCV system, or its effects.

 

It was the very first kind of emission reduction introduced in the early 60's ( probably in CA first ). It has one big side benefit in keeping the crankcase fumes ( read stink ) out from under the hood that you get when the engine is just vented to the atmosphere. Ride in a pre 60's vehicle, especially with it all closed up, and you'll see what I mean. I even had a '51 Ford that had an aftermarket system apparently from the 50's on it ( had a cute little baby sized oil bath breather for the oil cap ). Anyway, it does cause a slight loss in manifold vacuum, so the idle quality changes when it is added or removed. Running a PCV system with unbaffled aftermarket valve covers ( that flat plate they rivet in some under the hole doesn't count, it needs to be the sheet metal kind like on stockers ) results in the problem you were having. There is enough vacuum in the crankcase to pickup the oil mist that is flying around in there and can result in even worse oil consumption than you were having. We found this out the hard way on a built 289 my brother had in the 80's. I built it and he installed Moroso chrome steel valve covers on it. He fought the oil consumption problem for thousands of miles ( as bad as a quart in 300 miles ), and after much prompting from my boss he finally installed a set of Edelbrock covers and problem solved. You can run without it, but it tends to get messy around the breathers after a while.

 

I've also heard that the combustion blow-by causes a corrosive environment in the crankcase.
Just my 2¢

 

Which Edelbrock valve covers are you talking about? I'm planning on getting the Edelbrock Elite covers, the tall style ones, because I need extra height to clear my roller rockers. RIght now I've got 3 gaskets glued and stacked to give me the 3/4" extra clearance. I'm also looking at the Milodon covers, they advertise special design that keeps oil out of the breathers, but I hate chrome when polished aluminum would do so much better. Chrome looks cheap to me, and nothing says class like Edelbrock, and polished aluminum. Thanks for the response, I'm interested in hearing which ones eliminate the oil consumption.

 

Sorry TK, but they were the chrome steel ones. Whichever ones you are considering, look inside. There should be a rectangular sheetmetal piece that fits down between two of the rockers. Compare it to an old set of stock steel covers if you have any. Also the PCV system helps keep the oil cleaner by helping to eliminate some the moisture in the crankcase as it evaporates and keeps it from mixing with the oil and forming sludge.