Another question concerning the PCV valve

[brumbach]

Suction is obvious at the PCV valve. Should I also experience noticeable suction at the valve cover breather during idle?

 

[Mikey1]

Usually no breathers on 327 engines....so what setup have you got ?

 

[brumbach]

I've got a 68 327 block with 66 heads and intake. The pcv valve is on the driver's side valve cover with a breather on the passenger side cover. At idle, I have strong suction at the valve but when I pull the breather and place my hand over the grommet, there is no noticeable suction. Should the suction at the breather side be equivalent to the pcv valve side?

 

[Mikey1]

A 327 does not need valve cover breathers.....

the pcv valve is just a small orifice in a brass housing that sits aside the carb.

Can you post a picture of your setup with the air cleaner removed ? Take pictures from passenger and drivers side direction.

What kind of carb are you using ? Maybe it is not connected correctly.

 

[JohnZ]

I've got a 68 327 block with 66 heads and intake. The pcv valve is on the driver's side valve cover with a breather on the passenger side cover. At idle, I have strong suction at the valve but when I pull the breather and place my hand over the grommet, there is no noticeable suction. Should the suction at the breather side be equivalent to the pcv valve side?

Your setup will work fine, as long as the oil fill tube has a sealed cap. You're seeing good vacuum at the PCV due to the small diameter of the valve orifice and hose; the vacuum at the breather opening in the other valve cover will appear to be less, due to the much larger area of the hole. The same amount of air is moving through the crankcase, but through two different-size openings. There's no other entry point for ventilation air into the crankcase besides the breather, unless the oil fill cap is not of the sealed type.

 

[JohnZ]

A 327 does not need valve cover breathers.....

the pcv valve is just a small orifice in a brass housing that sits aside the carb

His setup does, due to having a later block that doesn't have the vent hole at the rear to let air into the crankcase from the air cleaner connection. The brass elbow fitting on the carb (with a hose to the oil fill tube) was only used through '65; starting in '66, a PCV valve was used instead, screwed into the oil fill tube, with a hose to the large PCV nipple in the carb base. He could have used the oil fill tube as the location for the PCV valve, but, lacking the vent hole in the back of the block, he had to use at least one valve cover with a hole in it as the intake for the PCV system (where he has a breather).

 

[Mikey1]

OH.....YES SORRY 68 block !

...sometimes my eyes read quicker than the brain works....