Thread: crankcase pressure

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ok this is really just an annoyance issue that i have....

1978 4-bolt Chevy 350 bored .060
flat top pistions w/ 14cc valve reliefs
64cc cast iron heads 2.02/1.60
lunati voodoo 60102 cam .468/.489
performer RPM intake, holley 650 dualfeed
figured 10.77:1 compression

i have one open breather on each valve cover but i seem to get way to much pressure because i constantly get oil blowoff coming out of the holes in the bottom of the breather caps... was thinking about running a pcv valve on one if not both valve covers to hopefully eliminate this problem... any suggestions on which valve to use and how to run them?

This question comes up many times on this forum, the best thing to do is do a SEARCH on this site for
PCV or Positive crankcase ventilation
There has been heaps of talk as well as some good pictures.

Andy
(still rollin')

O.K I tried it myself type in the search area:

positive crankcase ventilation

you will find the "good stuff" there

Andy

pcv it and if you're worried about sucking oil into your system setup an oil catch can

you are probably washing down cyclinders by running too fat. try leaning it out a little and put some miles on it. i run moon covers with no holes. pcv is in the intake and a large moon breather on the dr side cove. relieves the pressure without making a mess.

the pcv

Stock covers have a baffle under the breather hole. Without some baffling, oil will be blown out the breathers.

Originally posted by shine
you are probably washing down cyclinders by running too fat. try leaning it out a little and put some miles on it. i run moon covers with no holes. pcv is in the intake and a large moon breather on the dr side cove. relieves the pressure without making a mess.

Classy looking engine.

Doesn't the Moon breather in the PCV system suck in dust?

Or is there a filter inside?

Originally posted by R Pope
Stock covers have a baffle under the breather hole. Without some baffling, oil will be blown out the breathers.

there are baffles under the breathers in both covers... the oil comes out like steam and eventually fills the element inside of the breather until it slowly leaks from the holes.

Shine... nice lookin setup ya got there too

this is mine a few months ago prior to installation...

i have several of these on the road. no blow by, no leaks from mains. one is going on 5 years and still is dry. no crankcase pressure, no leaks. this is lloyds 41 . 350/200r4/4:11 gears.

Shine, that motor looks absolutely gorgeous!!

the moon breathers have sponge filters in them. i have yet to have any oil come from one. excessive crankcase pressure is comp leaking by the rings usualy due to running rich and washing down cyclinders. i have fixed countless cars by leaning them out. out of the box carbs are notorious for this. i would lean it and change oil and put some serious hwy miles on it to reseat the rings.

I picked up the stuff to run the pcv so hopefully ill get that accomplished this weekend... i have to switch around some vacuum lines on the carb to run it... there is only one 3/8 vacuum port and right not its running to my brake booster, is it ok to T off of this one or should i just adapt the pcv to fit on one of the smaller ports?

Shine... i have the edlebrock breathers, they both have some type of sponge inside of them but it doesn't help much... ill try leaning out the carb some too...

thanx for the help!!

ok so i checked my oil today... was almost 3 quarts down!!!! PCV goes in this weekend for sure!!!! can't believe its actually building enough pressure to push oil out that bad...funny tho, never any puddles or spots on the ground and no smoke so im not burning it... where the hell is it going???? lol

also anyone have any input as to what i should do about running that pcv line with only one larger vacuum port? drill/tap a carb spacer... make the line fit to a smaller port which i have open... or maybe even T-off of the brake booster which probably isn't the best idea...

T-ing off of the brake booster shouldn't be a big deal as long as your motor is making proper vaccuum..... its all coming from the same source