performance 350, or loud oil stove?

[grnmnstr]

Anyone ever heard of a 350(4-bolt main)block that is built up so much that too much pressure is building up in the crank case that the valve cover oil breathers can't let the pressure relieve itself fast enough; therefore, forcing some of the oil to blow past the back 2 pistons?....(RPM's must be above 3500 and is more noticeable going up steep hills or under heavy load).....should I run 4 oil breather caps at the valve covers?....compression is good and equal at all 8 cylinders, heads are freshly done, all gaskets new, flat top KB pistons, steel crank, heads plained....compression very high (anything below 92-93 octane runs rough).....any suggestions would be useful........thanks

[95 Silverado]

I've seen this problem on engines before, but it's not usually a result of how much the engine is built up. either the breather system isn't adequate or working properly,or the engine has blowby and the breathers can't handle it.

  What does your present breather system consist of? are the breathers open or are they baffled to prevent oil from being carried out of the breather? It could also be an oil system problem. are the drain holes in the head blocked or restricted? if they are the oil at high RPM's could be building up in the valve covers and forced out because they aren't draining fast enough. What type oil pump are you using? A hi-volume pump could be pumping the oil up faster than it can drain back. they sell oil restrictor kits to limit the amount of oil that goes to the top of the engine for that reason.

  with the engine idling, if you remove one of the breathers, is there pressure present at the breather hole, does it increase with the RPM's. a small amount of pressure would be normal, but a lot is a sign of blowby, caused by poorly sealing rings. the engine doesn't sound like it is built up so much that it should do this, if you find out what is causing it, you can fix it, adding more breathers isn't usually the best answer.