After trying several solutions to the crankcsse oil seepage/leakage problem I finally found one that actually works very well.

The Sixes do not have quite the same problem as the Fours. In the sixes a PCV valve can be inserted between the rocker arm breather to crankcase junction & the oil filter base. This provides a slght vacuum on the crank case under light to moderate throttle openings.

The Fours have a restricted valve cover outlet opening going to the air filter base joint in which a PCV valve could be inserted to provide a slight vacuum on the crank case under light to moderate throttle loadings. The filler cap is normally sealed, with the road draft tube providing necessary ventilation air. Much better than nothing.

A real solution. The carb to carb balance tube is drilled & tapped to accept a 5/15 fitting. This becomes the new source for the PCV valve inlet.

A tube is routed from this new manifold tap, through the added PVC valve, to the original valve cover breather outlet fitting. The original road draft tube is capped.

The PCV calibration allows a moderate vacuum to be pulled on the crankcase. The PCV calibration allows more flow as the throttle is opened. At worst case, full throttle, the valve prevents any build up of crankcase pressure, but never allows a positive presure in the crankcase.

Under actual tests, I show 5 inches of vacuum on the crankcase at idle to light throttle, 7 inches of vacuum at moderate to high throttle, & zero vacuum but no presure at full throttle.

Only a couple of flats on the carb main jet calibration were needed to bring things back into balance.
No more oil leaks from the engine. When the engine is shut off you can hear several seconds of vacuum leak into the crankcase.

I used a Napa #2-2982 PCV vave. A pic is attached.
D

Dave,

This is a great idea and anything that keeps Oil on the inside of 100's engine is a good thing. The "tee" I assume connects the Valve cover, Air Breather and Balance Tube? With the Crank vent blocked off....


Michael
55 BN1......

The original valve cover baffled side vent is connected to the large diameter side of the new PCV valve via a short large diameter hose. The right angle plastic PCV valve outlet is connected back to the new intake manifold connection.

The straight PCV valve plastic connection is capped.

Not shown is an added right angle hose nipple in the oil filler cap which allows connecting a temporary vacuum gage to monitor actual vacuum levels under various driving conditions. This connection is normally capped.
D

Dave,
that is elegant. Thanks for the R & D. Do you think I could use the capped portion of the tee fitting to run a line to my front shock absorbers? It would be easy to put a nipple on the filler plug and keep a vacuum on the shocks to keep the oil in them too!