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Discussion Starter · #1 ·
My rover powered cortina has one of those chrome dome shaped breathers on each rocker cover. There,s a fair bit of mist coming out of them at tick over, probably a lot more at speed.
Should one of the breathers be connected to the carb and the other haves filter on it?
It has offy intake and a 390 holley
Thanks
Ian
 

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fit a pcv valve in one rocker cover grommet and pipe this to manifold vacuum such as the big pipe fitting at the side/rear of the carb. it'll help no end.
 

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they're pretty universal to most all european and yank engines so local parts supplier or one of the yank parts suppliers will do one for you.
 

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Ok will order one of those, thanks

What is the theory behind these valves,and apart from all that mist in my engine bay what is wrong with 2 breathers?

Ian
basically engine vacuum draws the fumes through the valve and they get burnt in the cylinder. there is a non return design built in to stop air/fuel mix getting in the crankcase. because the vacuum sucks on the crankcase the other breather is not blowing it now sucks in. they replaced the old road draft ventilation that was commonplace before and your 2 breathers are acting as now, only the fumes were piped under the car.
your 2 breathers are fine apart from the oil mist on the valve covers.
 

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is the servo pipe connected to the right rear of the carb (under the vac' sec' diaphram) or the inlet manifold? if the carb and there's no other vacuum ports on the inlet you can 't' into the same place for the pcv connection. or see here, page 2 for the pcv valve and page 10 for a servo fitting (remove a manifold blank and fit in place for the pcv to connect to) http://www.avrosystems.co.uk/realsteel/section9.pdf
 

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't' into the servo pipe near the carb and connect the 't' to the pcv valve at the valve cover. leave the breather on the other valve cover as is.
 

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The basic idea is to pipe one rocker cover vent without a pcv into the air filter. This allows blow by fumes to vent into the top of the carb under load.
The other rocker cover with the pcv fitted should be piped into the carb under the flaps so that the fumes / vapour can be sucked out of the engine under decelleration.

The early Rover engines have a vent connection at the back of the valley which used to have a filter fitted. This was to allow air to flow into the engine to make up for the suction created under deceleration so the fumes could be sucked back in from the rocker vent into the engine with fresh air being drawn in to compensate for the drop in crankcase pressure. I'm pretty sure that was the idea??

I ditched all my pcv stuff long ago as the car is now race only. But back in the day, the main reason I went with the pcv setup was to reduce the smells coming into the car on the road.

These days I have both rocker covers with oil filler cap holes. Both of the filler caps have been converted to large breathers with stainless steel mesh fitted into them so the engine can get rid of blow by gasses with no restriction when I'm racing ;)
 

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Discussion Starter · #20 ·
Mmmh. My current idea is to leave the front chrome filter thing as is and fit pcv valve to rear rocker cover teed into the vacuum pipe that also goes to the servo.
Just want to stop the smell and oil mist in the engine bay

Ian
 
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