[mr48chev]

There are two causes for engine oil leaks where the oil isn't under pressure from the oil pump. Something wrong with the gasket's sealing or excess pressure in the crankcase and internal spaces of the engine connected to the crank case such as timing cover and valve cover.

When I built my T bucket in Texas I put two breather caps on the valve covers and no pcv valve. = all the race cars had two breathers. Even with a fresh re-ring job on the 283 there was always some signs of oil around the breathers. Worse if I was driving at highway speeds for a distance and I drove it to school and work every day in good weather that summer. When I needed an engine in my 48 we pulled the 283 out of the T and sold the T and I put it in the 48. It ran like a bandit in the 48 and 80 mph was 3000 rpm. The engine always had oil coming out of the breathers and I had removed and plugged the road draft tube on the 61 engine. Dumb move by a 28 year old who should have known better but didn't figure it out until he read an article in a magazine about running a pcv valve system to alleviate the exact same issue I was having. 6 bucks worth of parts later I was in business and my oil mess went down a ton.

Road draft tubes work but they only work when there is a decent air flow going past the end of the tube and the end of the tube is meeting that air flow just right, that is using venturi effect to draw the fumes through and out the engine into the air stream but does nothing when the vehicle is sitting at a stand still except let fumes if they are being pushed out by blow by drift up around the front of the car. Older guys always can remember that car in town that had a cloud of oil smoke around the front of it at every stop light.

I'm not well versed in dealing with crank case pressure on a blower motor. I'm not sure the one guy that I know or knew is still alive or able to tell you. He drove a 29 Model A with a small block Chev with a 671 on the street and towed a camp trailer with it. He also crewed a AA fuel dragster at major meets.