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Hi Gary, my engine is modified much like yours with 2bbl Weber & its air filter, I do not have the original stuff close at hand to verify the original PCV setup for guidance on how to reconfigure with your revisions, but looking at my engine I think I have it figured out more or less. The original takes air from a nipple on the bottom of the air filter housing through a hose into the nipple in the center of the R valve cover. This supplies clean fresh air to the crankcase. A similar nipple on the L valve cover leads through a U-shaped hose to the PCV valve which screws into the carb adapter plate between carb and intake manifold. Suction (engine vacuum) regulated by the PCV valve thus pulls crankcase fumes into the intake rather than venting them to the atmosphere, reducing pollution.
I am not sure what the original oil filler cap looks like but in this type of system it should provide a pretty good seal to the valve cover.
"Will adding a "T" to the hose connecting the valve cover vents and then connecting a hose from the "T" to the air cleaner create a nice little vacuum that will draw the blowby out of my valve covers and back into the intake to be burned?"
Yes as long as you have an air inlet to the crankcase, which your picture shows, ie your filter-type oil filler cap.
"Why didn't they just do this on stock motors?"
Apparently they did. Haynes manual refers to early "semi-enclosed" and later "totally enclosed" PCV systems, but no cutoff date. (Chapter 1 Section 25 p. 26.) Crude sketches of both types indicate neither has a PCV valve, if that is true there is a still later type (eg my '69) that does. Systems with PCV valves are more effective at controlling crankcase emissions.
"The reason I have a breather cap is really to allow air into the valve covers in the case of vacuum."
Well not exactly...a crankcase is never sealed from atmosphere without venting. In the absence of a PCV system there will always be slight pressure in the crankcase from blowby, this increases when the engine is under load (bigger event in the combustion chamber) and dramatically when the engine gets old and rings wear and no longer seal well. Those blowby vapors need someplace to go, either to atmosphere or back into the engine. Only with a PCV system will there be vacuum in the crankcase, that vacuum pulls the vapors back into the intake manifold.
"Or am I nuts?"
.......What's your car's name again? Do you talk to it? Does it talk back?
Before my valve job I had suction at the valve cover vents, now I have blowby. Sound right?
As above, only way to get vacuum in the crankcase is with a PCV system. If your setup does not apply suction to the crankcase, either with or without a PCV valve, you will only have pressure from blowby. Degree of pressure or vacuum should be slight in any case, possibly hard to detect without sensitive gauges. Hope this is all semi-clear. K
posted by 65.164.10...
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