The PCV valve grew from necessity. An military application was probably the main cause. When the civvy 216 and later truck 235 low pressur engines were used in military/battlefield conditions the practice of using draft tubes and vents cut as intake on the valve cover just behind the acorn nut holding the valve cover became a problem...... first dust in North Africa than water seapage during beach landings. Well beach landings could be dealt with using temporary putty to seal the engine covers, battery caps and battery poles,etc..... but usually the putty was to be removed ASAP upon landing. I think the North African campaing may have been the major contributor.
Early attempt by GM Canada for CMP military application was to stop punching the vent slits in the valve cover and installing a fancy miniature oil bath cleaner on the valve cover... this dealt with the air intake to the crankcase then they removed the draftube and retained just the vertical part of the draft tube with the top part sealed crimped in place instead of the oil filler cap that the civvy model had.
Then came the PCV metal two piece that could be serviced by unscrewing the top/bottom part and cleaning up the inside plunger and spring. This PCV setup was hard plumbed from the side of the new sealed draft tube to over the front of the valve cover to the intake manidold just under the carburator. Thew actual PCV valve was located vertically jusy below the carb entering at 90 degrees into the square penum chamber.
Now for finding these PCV valves.... identical model, all steel, were used on WW II Jeeps..... and most Jeep parts supplier shops will have them in stock..NOS...for about $25.... check Peter De Bella as a Jeep supplier.
You now have the birth of the PCV valve set up very similar to what I found on a 59 261 with solid lifters and 4 speed...... which has since been rebuilt and sitting in a 1940 Canadian Military Pattern cab 11 1940 RH drive 4x4 truck.
I would love to illustrate the above with my pictures but find the posting difficult unless I can send them to a memebr who will post them for our readers.
Bob C.
