Yes, I guess determining the root cause would be the best thing to do.

I've researched worn rings, blow-by, and positive crankcase pressure a bit and it seems like the only real symptom I seem to have is positive crankcase pressure - seen as both pressure from the rear engine breather and seeping oil seals.  Engine power seems fine (engine is not under powered and seems to run strong).  Plugs are all the same; dry with a dusting of mocha colored deposits.  No smoke from tail pipe from either cold start or during acceleration.  I don't seem to have thinned-out oil from unburnt fuel being blown past the rings.  Time to buy a leak down tool and do another test I guess. That should give me some more useful data.

Let me get us back to Jeffs original post and answers. He mentioned no problem with compression or leak down tests. But both of those tell us about the health of the system with the valves closed. When the exhaust valve is open and compression pressure is escaping, it may try to go out worn exhaust valve guides, or perhaps incorrect ones. Could that explain a source of blowby ?

So I am having high pressures on my 1275 bored .030 over. The PCV valve coming off the crankcase and has been cleaned and runs to the HIF44. I have a silicone valve cover gasket which pretty much stops anything from leaking (it might have very minimal leakage). The PCV valve on the crankcase is all I have in the way of reducing pressure. The last time I did a compression test last year, I was at 206 across all four. Leakdown test was a very minimal air pressure reduction through all four. Upon startup, the exhaust puffs a very small amount of white smoke. When running, it appears to burn nothing. But I have to add oil every 1000 miles or so. If my pressure gets to bad, the oil dipstick pops out causing an oily mess (This does not happen to often, I think the pressure is on the hairy edge though). My plugs are pretty oily when checking on cylinders 1,2,3, (bad rings)? I received the car last year not knowing how the engine was rebuilt. I think it has bad rings on three cylinders. Winter time project is to re-do the head and valves. Eliminate that, then do the block if needed next winter. In my opinion, I going with bad rings as being my dilemma. To much detontaion bypassing the rings going into thee crankcase.

On a similar note I recall a comment by CupCake implying you can never have too many crankcase vents on the A-series.  Based on that I simply assumed that my situation is not uncommon and I was hoping adding additional breathers would help alliviate my issue.

I can tell you how a baffled oil can catch will work in about two weeks. I just ordered one. I tried the PCV valve off the rockers to the manifold, and it did work for less oil out the valve cover cap, but you could tell I was burning oil by the smoke coming out the back end. I then switched the valve cover PCV hose to the air filter but my vacuum gauge said I was pulling NO air through the hose. Apparently the K&N filter did not pull past the tube stuck through the back. So, on to the catch can to filter the oil and vapors. I will give you an update by next week.

Jerry

I added a PCV valve to a HIF44 manifold so you should be able to do it as well.  In the case of the Weber manifold, I'm not sure what effect adding one would have on the cylinders the runner feeds.  

One question is why do you have so much pressure in the first place? Are you getting excessive blow-by from the cylinders due to worn rings, cylinders, valve guides/seals? Or some other phamtom leak? Have you done compression and leak-down tests?

The next question: is the vent you have actually working?

Next: if the engine was built as a fast street 1310, why wasn't adequate breathing included in the build?

Next: since it is an A-series, couldn't you add a vent to the tappet cover, like the 1275 Coopers had?

Next: couldn't you add a vent to the rocker cover like the 850's had?

Next: can you put a port in the intake manifold to draw vacuum for crankcaase ventilation, presumably with an apropriate PCV valve set-up? You say running a PCV system is not a reasonable option for you. I'd imagine an oiled clutch and a fully rust-proofed engine bay (oil-coated) would not be reasonable options either. (Ya gotta bite a bullet.... your choice of which one.)

I'm asking for advice and real-world experience for addressing positive crankcase pressure on an A-series engine.

My goal is to eliminate, as much as possible, the oil leaks from the two output shaft seals, the oil leak from the clutch housing drain hole, and the seeping oil out the valve cover filler cap.

I have a 1310cc A-series, built as a fast street engine that I take to weekend track events somewhat regularly as well as use it for an occasional street driver.  It currently has a single vertical breather on the flywheel housing.  It's currently running a Weber carb that doesn't have a vacuum port, so venting through a PCV into the intake is not a reasonable option for me.

After researching the forum for solutions I believe the culprit is positive crankcase pressure.  Just last year I replaced both output shaft seals and the rear main seal yet I still have a lot of oil getting past those seals - reinforcing my thought that the issue is positive crankcase pressure.  My plan at the moment is to fit an oil breather tank inside the RHS wing and run lines from the flywheel housing beather and the valve cover to the breather tank.

1) has anyone used, with success, the fuel pump breather adapter sold by the host?  I did read a forum post indicating that above sustained 4500 RPM resulted in the crank splashing large amounts of oil out that breather port.  The product sounds good in theory but if it will push oil when running over 4500 RPM then I'm not sure it will work in my situation.  Anyone else have any real world experience with this breather?

2) I've seen crankcase venting setups that run breather lines from both the valve cover and flywheel housing breather to a breather tank.  I've also seen a setups where a line is connected from the valve cover to the flywheel housing breather, then another line from the valve cover to a catch can.  Is one a better solution than another, or is it just personal preference?

3) Being a pre-A+ block there doesn't seem to be a timing cover breather available.  Is it reasonable to weld a breather bung into my exising cover?  Maybe there's a reason that these front covers don't have breathers.

I would love to hear about any other solutions that you've found works.