KJL

I have been running one but now I am just using a vent on top of each valve cover, wouldn't this be good enough? The car is not a daily driver.

Easy Mike

Define "good." PCV is a closed system which ensures crankcase gases do not find their way into the atmosphere. Sounds trivial until you multiply it by 50 million cars.

Your vents let the fumes out.

73, Dark Blue 454

You need to run PCV system on the street for numerous reasons, the biggest being, harmful blowby vapors are replaced with fresh air. (ALL engines have some blowby).

Also, liquid moisture, which collects on components inside the crankcase upon each cool-down cycle, is vaporized (if your oil reaches 212f) then removed via the PCV system.

A pair of breathers only allow a crankcase to 'belch'. No fresh air is introduced to the crankcase. Note the term "Positive" of PCV instead of "passive".

donyue

I added a PCV system to my engine. The vents worked okay, but the vents left oil film on the valve covers and overall in the engine compartment.

It's is not a big deal with a non-daily driver but I would rather keep my engine compartment free of oil film which will just attract dirt and make a sticky mess over time. JMHO.

C3 Stroker

I have a 427sb and run just vents (one on each valve cover). Mine is not driven daily, so my valve covers are mostly clean. Most (almost all) people I know with hi-po street engines (500+ hp) do not run pcv valves, just vents. Some run vacuum pumps.

gkull

That is all I have. My problem with PCV is they don't flow at wot when you have max blow by. They screw with the A/F curve. oil mist in the intake is the cause of build up carbon on the intake valve stems restricting air flow

7T1vette

No, you don't need one, at all. You can get rid of it and just clean out your oily engine compartment once a month...

Keeping a PCV system intact--and working--is a "no-brainer". It is virtually maintenance-free, causes no loss of performance, and eliminates the dreaded "oily engine compartment" syndrome.

What's not to like???

gkull

Lots of different motors under my hood. 60-75 thousand miles and just K&N breather filters.

They are tall tubes and my crane gold stud girdles might block all the rocker splash. I do refresh my motors with new rings..... every 5-10-15 thousand miles.

I never did think about oil under the hood or see much of any, maybe I am lucky.

I bought these tall cast Dart valve covers and I drilled a hole in the side years ago on my first SR motor and installed a PCV. I was in a motor shop for something and the owner ask me WTF! LOL We welded the hole shut. See where it is welded on the passenger valve cover Also notice how clean the intake plenum runners are on a motor I am taking apart for new heads?

Solid LT1

I re-engineered the crankshaft ventallation system on my 72 LT-1 years ago after observing the build up of moisture after the Vette sat between outings. Head/intake gaskets can weep while sitting and I live in a humid area. Thinking I didn't want the roller bearings in my rocker arms exposed to water, I reinstalled a PCV system. The system wasn't a closed crankcase vent, both valve covers vented to a catch can, then I put an older factory hi-rise intake on and installed the oil filler tube from a C2 Vette with a PCV valve on that, my moisture problems went away after going to this set-up

LudemJo

OK, so I have another question related to this. On my 74, the driver's side has what I assume is the PCV valve with a ribber hose going to the center vacuum port at the base of the carb. The passenger side has a hose that is not hooked to anything because the previous owner installed an aftermarket air cleaner without the port to hook the other end of the hose to. Is this hose the inlet side of the system? If so, would a breather be acceptable here? Or, alternatively, should I figure out how to install the fitting in my air cleaner to hook the hose to?

This issue is way down my priority list of work to do, but the question was out there so I figured I would ask.

John

7T1vette

An intake breather/filter on the right-side cover would be preferable to an open tube sticking out of that cover...simply because it would limit the amount of cr@p getting into the engine. But, it could allow some engine vapors to escape that breather under certain conditions.

Still not as good as plumbing that tube up to the air cleaner system you presently have.

Super6

The rubber hose can either be run to a fitting on the air cleaner base or replaced with a breather. The fitting is probably available separately, but it comes with aftermarket air cleaner assemblies.

I have a Moroso oil mist/air separator between the PCV valve and the intake connection. It does accumulate some oil in it and it is easy to drain. I don't know if it is 100% effective, because I previously had some intake studs that weren't sealed that were allowing oil to get drawn into the intake.

MIKE80

I recently replace the Edelbrock crankcase breathers that I had on each valve cover because they were seeping oil, making a mess, and dripping onto the headers. I replaced the right one with a chrome breather that is connected to the air filter drop base using a flexible stainless steel tube, so it's supplied filtered air. Here's the fitting I bought for the air cleaner dropbase connection. http://www.jegs.com/i/Edelbrock/350/1205/10002/-1




The left side was replaced with a billet PVC valve which is routed to the large vacuum port on the rear of the carburetor. No more mess.




At some point I may add a catch can setup. But this cleans up the mess for now. Here's the old breather setup that I replaced.

Super6

Mike80 - Switching from 2 breathers to the PCV/breather (whether on the valve cover or through the filter) puts oil into the intake where it builds up as a hard cruddy mess (technical description) around the intake valves just below the stem, where the obstruction messes up the air flow into the cylinders and if there is enough blow-by, the plugs get a coating too. This is why most racers, etc. run two breathers only, so the performance of their engines doesn't degrade. That's why I have the separator in the line after the PCV valve.

Mike Ward

The stock hose on the passenger side has a coarse air filter fitted to it. A breather with a similar type of filter would work fine.

mrvette

Biggest reason for a functioning PCV system is that totally outrageous SKANK SMELL of the fumes.....one wiff of that crap knocks a T Rex on his ***......

MIKE80

I currently have an electric vacuum pump for my brake booster. I will be replacing the vacuum booster with a hydroboost setup at some point. So, I've been toying around with the idea of adding an air/ oil separator maybe something like this http://www.jegs.com/i/JEGS+Performan...52206/10002/-1. Since I won't be using the vacuum pump for the brakes, I was thinking of connecting it to the air/ oil separator to kick in at WOT. Also keep the hose going back to the carb T'd into the vacuum pump line with a check valves so it will still function during normal driving. It will be a while before I'm ready for the hydroboost, so I'll probably just pick up the air/ oil separator for now. Any thoughts on the electric vacuum pump idea?

roscobbc

What he said - probably the reason for the hair 'style' on his signature photo!

KJL

I never considered the oil film.

Easy Mike

So that's where they all went.