Originally Posted By Coke
Ok don,t worry.They are not expensive parts,so i can order a couple of pcv valves and use the most aproppiate.The stant cap you posted looks good to start.What i don,t know is why all these breathers-pcv caps do throw vapors to the atmosphere instead to have a connection tube for the air filter.

OK.
You can try one for a Chrysler v-8 and if you want to experiment,
ACDelco CV736c has is reported to be good for engines with lower manifold vac, and has 3/8" connection (suction side). I don't have the other diameter.

As to why so many open breathers? That might be a sociology question as much as a technical one. laugh2

On a good running engine, the most of the vapors will to through the PCV valve and the breather is just air in. Before 1960 or so, cars here used draft tubes to evacuate the crankcase. The low pressure under the moving car sucked the vapors out. Probably the same in Europe.
To address the greater blow at high rpm, wide open throttle, some racers use vacuum pumps or evacuation tubes in the exhaust.

One problem with PCV valves is with engines that have poor manifold vacuum at idle. There has to be enough vacuum at idle for the valve to be in the most restrictive position. I *think* if your engine can get 11 - 12"Hg at idle, it should be OK with a stock PCV Valve. This why some people experiment with different valves like that CV736. I had plans to test the flow of PCV valves but that's been sidetracked.