The names Gordon, I live down here in Adelaide Australia & I am presently rebuilding a 256 Y Block to install into my 48 F1 – upgrade from the flathead 6 in there at present 

This is my first Y Block & I have many questions on the rebuild one of which is the choice on valley covers (WITH  or WITHOUT  REAR BREATHER) if I choose a cast alloy one with a fitting for a PCV GROMMET can I then do away with the “Block mounted bake bean can breather” which I am told can get fumie  –
or Do I need a PCV set up or can I just rely on the oil filler cap as a sole breather source? – do I then need to do anything else? is there enough ventilation space from sump to valley to be able to do this? (oil drains and distributor shaft cut outs)

 

I see a few aftermarket valley covers with no oil filler or PCV Grommet breather – how do they achieve engine breathing (oil filling?)

If you install a Valley Cover with the rear breather opening ( either late stock or aluminum aftermarket) & a PCV setup, you should remove the block side canister & install a gasket & cover. Do not rely on the oil filler cap screen only, for crankcase venting. That was the original air intake point for the system. Unfortunately that was a weak point in the system, as the screen tended to get plugged up & it was often not serviced. However, the crankcase does require some sort of filtered air intake.. Others on this site may have further details on the best way to complete the setup, depending on what carb & intake manifold you are using etc.


Paul

G'day Gordon. You live only about 5 miles from me,

you are most welcome to come view my PCV conversion and talk Y-block.

My mobile is 0416 084 756.

South Australia

Thanks Paul and Al - spot on response

Cheers

I am using the side breather and rear valley pan breather and so far no problems with any pressure buildup in my 56 crown Victoria at all. I have a friend that's  been doing this for several years and no problems either.

-Gary Burnette-

Gary: To clarify, is that without a PCV setup?..


Paul

Hi all just signed up ? I have a 56 merc 312 end and yesterday it started to spit oil out the crancase vent draft pipe?never did it before car runs the same.thought maybe lost rear seal but was vent pipe.its the pipe drivers side lower.
Thanks

Check that the oil filler breather cap is not obstructed.Please dont take this wrong but is oil level  correct?

Oil was good pryer lost about 3 quarts not burning oil noticed oil pressure drop.did run short distance after with breather off didn't do it but not really very far didn't have oil with me
Would bad cap do that? Was bad lol Could a pluged oil filter do that ? Have the old still still on?
Thanks Bob

Oil was good pryer lost about 3 quarts not burning oil noticed oil pressure drop.did run short distance after with breather off didn't do it but not really very far didn't have oil with me
Would bad cap do that? Was bad lol Could a pluged oil filter do that ? Have the old still still on?
Thanks Bob