Solutions to solve the emission problems, (Smog) emitted by the average vehicle engine keep popping up on a regular basis on the majority of the old car forums. The majority of the retro systems proposed are over-engineered and complicated with little chance of actually working. A case in point; installing a PCV devise in the bottom of the intake manifold with no baffles to eliminate oil being sucked into the PCV, and servicing of the PCV requiring the removal of the intake manifold.
To clear the air I am going to clarify who I am. I am not an engineer, I have over sixty-five years of work experience on vehicles, large and small. I took Auto Tech in high school for three years because I thought I wanted to be a mechanic, my career took me in different directions. I have a very high mechanical aptitude, and I am very long on common sense.
It is fact that the adoption of the PCV in 1963 to the internal combustion engines in use at the time eliminated 90/95% of the emissions that entered into our air, the majority of the emission systems that followed during the '60's, 70's and '80's were knee jerk systems that resulted in engines that delivered poor performance and became commonly known as SMOG motors, a term synonymous with poor performance.
By the late '80's, early '90's the manufactures wised up and started building engines with better fuel economy and performance with lower CID, while at the same time delivering very high longevity..
By the '70's/'80's engines were so screwed up with EGR's air pumps, etc, yet the PCV kept soldiering along, doing it's job of keeping the air we breath reasonable clean.
OK, I have laid the ground work for my theory on PCV's:
I have re-thought the subject of converting an early flat head engine, in the process it dawned on me that I had already solved the problem when I converted my '57 Ford T-Bird to a PCV in 1973 so that the car would meet California's new emission standards that became law in 1975. The system that California adopted was another knee-jerk system called NOX.. This system required the elimination of vacuum to the distributor and the drilling of holes in the valve covers for fittings to which hoses were connect to the air cleaner. Drilling holes into the aluminum valve covers and chrome air cleaner on my Bird was not an option.
At the time I had two '64 Ford trucks that had the Y Block V8's and PCV's, therefore they were exempt from the NOX requirement. I secured a PCV system from a '64 292 V8, installed same on my Bird, the car met the CA standards for emissions, I was home free.
While looking for a PCV system for my Bird I discovered that the '64-65 GM trucks I had in my fleet had PCV systems very similar to the Ford 292 V8's.
Prior to 1963 the majority of the engines in use had road draft tubes for engine ventilation.
Ford and GM simply removed the road draft tube, fabricated an adapter to fit into the hole in the block, securing same with the same bolt that attached the discarded road draft tube. A length of hose and a PCV connected to a vacuum source completed the system, probably at a cost less than what the road draft tubes cost. Value engineering at it's best.
The early Ford 292's had a crankcase vent on the lower side of the block, '64 and later do not. The early vent has to be blocked off just like the pan breathers on some flat heads.
Now to the problem of installing a PCV on a flathead Ford V8:
The 8BA style of engine should be very simple because they have a road draft tube located to the front of the engine. The draft tube would require removal and be blocked off. Remove the fuel pump and pump stand, install a block fitting similar to the one used on the 292's, using a length of quality hose with a PCV in it, attach the hose to a vacuum source in the manifold.. There is no need for a secondary hose going to the air cleaner. That system is used on some overhead valve engines with the hose attached to the valve cover. Discard the troublesome mechanical fuel pump, use an electric. Placing the PCV in the port where the road draft tube was would not be a good idea. The vacuum could conflict with the fresh air flow coming into the oil fill tube.
The pre 53 engines, 59AB, 21A, etc., present some problems. The use of a 8BA intake manifold could be a simple solution, however, leaving the oil fill tube and fuel pump in place would provide a fresh air source. Drilling a hole into the front portion of the intake manifold, placing a threaded PCV into the hole would solve that problem.
On the theory about using vacuum from the base of the carb., and thereby making the fuel mixture lean, that is a normal place for vacuum for wipers, Columbia and/or power brake boosters. Most older engines run rich, and it is a fact that the enriched vapors from the PCV system tend to make the fuel mixture a little rich. We have had to lean out the fuel ratio on the majority of the engines I have converted to PCV.s
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