Well, the title says most of it. I’m trying to figure this out. The car is using about a 1qt of oil a tank of gas. Not smoking. No leaks (I hate leaks). Plugs are ok, not perfectly gray, but not coated in black gunk. But, I’ve been messing with the carburetor and in the process of taking it off and take the spacer off, the two cavities in the intake manifold (not in the airway but beside them) are full of oil. There is a sheen of oil in the intake airways. The only place I can believe oil could be getting that high in the engine is through the PCV line. I changed the PCV value with no luck. I’ve run with the PCV line disconnected from the spacer and the spacer port plugged. That works. But, I don’t know if I can run the car long term like that (fuel too rich because there’s no air flowing through that port and reduced engine fume circulation). Short of a catch can, I’m not sure what else to do. The baffle on the valve cover is all there. I’m trying to tune the carburetor (Autolite 4300) and it’s hard to do with all that oil mixed with the gas. It’s not a 2 cycle motor - haha).
My next attempt is going to be putting a longer PCV line on it and looping it up so whatever oil is in there has farther to go. Might sound silly, but I’m out of options.
The breather cover is there. It’s definitely not clogged. I’m not sure how to test it if it’s “wide open” I don’t know what flow resistance it should have.
The pcv valve is opening too much in high vacuum, low manifold flow situations, such as at idle or when coasting. The high vacuum pulls the valve wide open, and sucks lots of oil and blow-by into the manifold where the oil falls out of suspension as soon as it hits the large open area. You need to find a pcv with just the right stiffness to its internal spring. On my j code, a pcv from a 3.8 t-bird was the magic.
I had the same problem with a J code Cougar years ago. It wasn’t visibly smoking, but the tail lamps, rear bumper, valance, and the back of the trunk lid were covered with soot after a 200 mile trip on the freeway. And yes, it burned about a quart every 750 miles. In my case it was bad valve guides. The shop had knurled them so they lasted a couple thousand miles and then the heads had to come off to get new guides installed.
Hmmm. Interesting thought. Although, I don’t have any oily residue anywhere. I put the heads together myself. It’s possible. But, until I get the oil gone from the intake manifold cavities, I’m going to concentrate on that.
I’m not clear on the valve cover type, maybe I just missed it. But are you using the stock valve covers, or aftermarket ? Aftermarket van,ve covers OFTEN have a dismal baffle for the PCV system. If you are using stock vale covers, is the baffle still in place, has it been modified by a previous owner ?
In the meantime there are a couple of bandaids you can try. I’ve used both of these products, and they work beautifully, and for what they cost, they should be flawless :
oil catch can; it will trap the excess oil before it gets to the intake, of course you will still be using too much oil, unless you recycle the catch can oil. Don’t know if I’d do that, too many blow by acids in the oil vapor being collected…
a custom PCV valve might benefit you as well. Now THAT might help your oil consumption:
Nice! I have given thought to the catch can. Right now, the stock valve covers are on. The engine bay is done back to original. I had a pair of the “cougar” valve covers from Scott Drake on it. The baffles on those were much smaller than the ones on the originals. So, I thought I’d switch them to see if the problem went away. It didn’t.
I had some Scott Drake open Cobra lettered valve covers on my GT350 briefly. The baffles on those were wayyy to small, creating massive loss of oil . No amount of modifying would help, so I was forced to ditch them in favor of a stock type…
Wow! That’s good to know. I’ve seen those covers and I imagine the internal design on yours and mine are the same. I wonder if I were to somehow secure plastic scouring pad material in the baffles, if that would help. Might slow the airflow down some.
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