I’m not familiar with the 56s, but in general, cars built before 1961 or so are supposed to vent the fumes out through the road draft tube; the oil filler cap is where fresh air is supposed to enter the engine, and should not be giving off fumes and oil condensation.
It is important that the crankcase be vented to prevent corrosion cause by condensation of combustion vapors – so I think you’d best jack up your car and inspect your road draft tube – make sure it is open and not blocked by damage or some misguided plug, which some folks installed to keep the odors down. If the road draft tube is open and venting (you should be able to see and feel fumes coming out when the engine is hot and idling), but you still have crud dripping from the oil filler cap, I think your engine is getting a bit tired, blow-by must be getting worse. I don’t know for sure where your road draft tube is picking up the fumes – probably it is coming from the valley cover (under the carburetor) and going down the back of the engine on the passenger side, ending just below the bottom of the engine – it will be a plain smooth pipe, about 1 ¼ inches in diameter, probably with a tapered end to encourage evacuation when the car is moving.
While it would not be original, the best thing that ever came out of the EPA’s anti-smog rules was the PCV system, which solves the problem of what to do with the blow-by (crankcase fumes) – post 61 cars, with few exceptions, were mandated to have the PCV system installed, and in California, even older cars had to be retrofitted. We all complained about big brother forcing us to do things to clean up the air, but in this one case, it probably saved a lot of engines! There were cheap and easily installed retrofit kits for all cars (with very few exceptions) – and many of us out her still have them on our cars, even though they are no longer mandatory for pre-62 cars, because they are actually a great benefit for cars, especially as they get worn and blow-by becomes worse. What the PCV system does is to vacuum out the fumes and route them into the intake manifold, where they are burned along with the fuel/air mixture. While this dilutes the normal fuel mixture, the effect is very small, and it completely removes the “old car odor” from the engine!
Dick Benjamin
From: mailing-list-owner@xxxxxxxxxxxxxxxx [mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of YBSHORE@xxxxxxx
Sent: Wednesday, September 20, 2006 5:47 AM
To: mailing-list@xxxxxxxxxxxxxxxx; mailing-list-owner@xxxxxxxxxxxxxxxx
Subject: IML: Oil Breather Caps, and for my '56 in particular
Has there ever been a device made whereby the oil breather cap filter which sits on top of the oil filler tube, which inevitably drips said viscousness, which is then sometimes sprayed through the entire engine compartment depending weather/driving conditions, or dripping onto the hot block and making for not-so-delightful aromas for the non fossil fuel people, etc., can a device be had that can "recycle" this dripping oil back into the crankcase via some hose overfill return or the like, or run it straight to the ground with a different style cap? This problem occurs for me after extended "full operating temperature" excursions, which is my preferred driving getaways.
How do other Imperialists deal with this apparently designed to drip cap?
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