Originally Posted By Mattax

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.



Interisting. i have seen that Moroso sells a system wich threads a tube in the header close to the out for this purpouse.

Also ,i have done a new test today.
I have stolen the pcv valve from my Jeep 5.2 magnum wich has a 3/8 nipple and i have connected to the 3/8 port in the rear of the carb.






The idle is erratic and low rpms when the pcv valve is connected.Rightnow ,this thing needs an open 6-7mm
(Sorry for the metric,1/4"?) hole for a decent idling .
When that port is open it idles around 750-800 and seems to throw less smoke and fuel smell.However the engine was still cold and i haven,t had the time for warming it up.

Regards,