I'm having a problem blowing oil out the valve covers at the gasket only when running the motor to 5300rpm. Normal around town and freeway driving does not leak. I've tried -

1)Paper and cork gaskets with no sealer.

2)Paper and cork gaskets with different types of sealer

3)Stock steel and MP cast valve covers

4)The expensive silicone or rubber Moroso gaskets with the steel core.

I've checked the vc bolts and they are not loosening. I've also tried different torque settings on the cover bolts. The head sealing surface is not perfectly flat as there are the "usual" small casting variances in the sealing surface that i'm used to seeing. The covers are leaking on both sides, but the driver side is the one blowing enough oil to drip on the header pipes.

I have a single Billet Specialties PVC valve on the passenger side hooked to the rear port of a 770 Holley Avenger vacuum secondary carb. The driver side cover has a single MP chrome breather. The motor is a stock bore 440 with auto trans.

So now i'm

Looks like you need another breather. Remember, the PCV system quits working under hard acceleration. There's no vacuum to operate it. I'd put a breather in each valve cover.

Are you running a evac system to the headers with
a exhaust, that could be pressurizing the crank case.
Sounds like you have a fair amount of air slipping
past the rings
EDIT
Or the valve cover/head suface is bad enough that
it isnt sealing and at revs the engine is pumping
enough oil to fill up near that area(that would be
alot) and its just leaking out. Do you see alot of
steam/air coming out of the beather when you rev it

the PCV system quits working under hard acceleration. There's no vacuum to operate it.

Backwards: the PCV is held to its smaller opening by vacuum against an internal spring. No vacuum: the spring retracts the cone, and the opening enlarges. WOT is as open as it gets.

Sounds like ring seal.

but there's little or no vacuum at wot to draw crankcase vapor. the system works best at cruise. two breathers in the cover opposite the pcv valve. it does sound like you have alot of blowby.

i had/have similar issues with my stock piston 440 but mine would blow the oil right out the dipstick tube under hard accel. i had pcv on one side and chrome breather on the other. i changed to an open element type of breather, like a KN type and it fixed the problem( more like a bandaid but i cant afford pistons and machining). try a better breather, it may help.

There is no smoke out the breather at idle or when I rev it. It does have the stock pistons and had a "re ring" I was told when I bought it. No smoke at start up after sitting.

No evac, I haven't been down a 1/4 mile track since they bulldozed Fremont drag strip back in the 80's for condo's. I know this is the "racing only" section, but I figured you guys would know more about the question than anyone...

I'll try a second breather and

Thanks for the help!

You might want to try a leak down test to make sure all your rings are good.

It could be just one bad ring and you might not feel a power loss if you broght it in that like that .

are you sure the vc is not hitting the intake runner?

are you sure the vc is not hitting the header flange

I have had to clearance cast vc before,they hit the intake runner and would not seal,a little work with the dremal and it was good to go

when you tryed the sealer on the gaskets did you let it cure over night before running it?

I use a little bearing grease on my cork gasket and the head also with some luck

I use the copper permotex and "glue the gasket on the vc and let dry over night and then install them with more copper sleeza cone and let it dry over night

I sure you have done all this,but worth asking/looking

and like said 2 breathers on the opisite side of the pcv valve should work also

are you sure the drain holes in the heads are open and not filling up with oil?

next would be a leakdown test

like max said, under hard accel, very little vacuum so very little pcv at work. if you blow oil out under hard accel, I would suspect a ring sealing issue. i had my last 340 do that. only blew out oil at 6000 rpm runs.

turned out that in my case, i had somehow broken the edge of the piston and actually caused a sealing problem (probably because of detonation)