312 Engine Road Draft Assembly

[Guest Len Sholes]

I am wondering if anyone can help me with a problem I am hoving on a 312 engine in a 57 Merc. The engine was completely rebuilt a short time ago and the problem I am having is oil coming out of the engine road draft tube. I have checked the compression and the cylinders are all between 140 and 145 psi. I have done a cylinder leak down test and have readings anyware from 8 to 10 psi. With this info I have to think that there is no problem with the valves or pistons. I have heard that the Y blocks were famous for this problem and one of the ways to cure the problem is to block off the factory installed crankcase breather and to install a breather onto the cover under the intake manifold. Has anyone tried this and if so does it work or am I missing something. The engine also has a leaky rear crankshaft seal and I am looking for input on this problem. Is there a better seal to use. Thanks for your response.