do you need PCV ?

[D111]

was looking at Keith crafft motors seems that most of them are not using a PCV Valve on one of the valve covers.

Just Purchased a quickfuel carburetor that doesn't have an additional vacuum input for one. So I was thinking of getting rid of My PCV on my roush crate motor.

Would It be detrimental?

Thanks

[healthservices]

Sorry new here, but yes a sealed motor would be bad. Blow-by would create enough pressure to cause seals and gaskets to leak...detrimental yes

Other alternatives would be to use:

a vacuum pump

Draft tube

Vents

Oil separator

[D111]

Originally Posted by healthservices

Sorry new here, but yes a sealed motor would be bad. Blow-by would create enough pressure to cause seals and gaskets to leak...detrimental yes

no not sealed omit the PCV and have A vent on each Valve cover instead of one vent and One PCV.

[cscobra]

Use a PCV--don't vent to the atmosphere. It's not going to cost you any power.

[rpatton3]

I think PCV came long before government intrusion got too bad.

Smog pumps did not show up in Fords until 1968. (1966 in Peoples Republic of California)

PVC is pretty benign.

Russell

[D111]

Originally Posted by cscobra

Use a PCV--don't vent to the atmosphere. It's not going to cost you any power.

Thank you but my question is will omitting the PVC and putting another vent Instead on that valve cover hurt the motor? I just don't have another vacuum input handy for the Pcv Anymore with the new Quick fuel carburetor It only has one and I want to use it for the power brake assist.

Thanks

[healthservices]

I think a pcv worth it. When there is a slight vacuum, it helps rings seal better too. In other words I would find a way to put a PCV in.

[rpatton3]

Old FE engines had a road draft tune out the back of intake manifold.

293 and 312 y blocks Fords never had PCV unless 1963 and 1964 Pickup trucks had it.

Depending on your engine, you could make your own draft tube.

Does your engine have an oil cap on each valve cover? If so, you could do PCV easily.

[D111]

Originally Posted by rpatton3

Does your engine have an oil cap on each valve cover? If so, you could do PCV easily.

it's originally set up just like yours, but now that I've switched to a quickfuel from a street Avenger carburetor I only have one large vacuum input on the base of the carburetor. So I am thinking of illuminating my pCV valve, just wondering if anyone knows if that would be harmful to the motor or is it just There to help Pollution/Emissions ?

[blykins]

Not harmful, no.....

But every street engine that comes out of my shop gets a breather on one side and a PCV on the other.

It's very simple to make it so that you can have both a PCV and power brakes. Did you talk to your BDR dealer?

[ha_pe_1968]

Hi!

Take a look at my gallery. It is a roush engine too. One vacuum line from the Carburator to the PCV, the other from the intake manifold to the power brake booster.

Greetings from Austria
Peter

[D111]

Originally Posted by ha_pe_1968

Hi!

Take a look at my gallery. It is a roush engine too. One vacuum line from the Carburator to the PCV, the other from the intake manifold to the power brake booster.

Greetings from Austria
Peter

Yes, my engine was like yours.

My question is, do we need PCV if so what is it doing beneficial for the motor Or is it strictly environmental. Just trying to learn a little something along the Way.

Brent you say you put A PCV valve on all your engines why? It seems like Keith doesn't just trying to find out.

I've searched And read definitions for PCV And it seems mainly for the Environmental requirements of the 60s

Think you
Dennis

[blykins]

Mainly for emissions. With the modern cylinder hone techniques and ring packs, you don't get any blow-by, but I never know how strict rules are where I send engines, so a $2 PCV valve and a $4 valve cover grommet is pretty standard issue. If a car were to go through an inspection in a strict state (such as CA), they would check for such systems.

Keith may not include one on his engines, but it would be up to the customer in that case to make sure everything was compliant.

[undy]

A little negative crankcase pressure is good for the engine. It keeps things well ventilated, recircs/burns unburned hydrocarbons and actually does help ring sealing, to a small degree. Plus, it's always embarrasing to me to have visible vapors coming out of your valve cover breathers.

The way Brent sets his up is the same way I do, breather in one valve cover with the PCV in the opposite one. It sets up a nice cross-flow ventilation through the engine.

Two thumbs up for the venerable PCV!

[Hydramada]

Originally Posted by D111

was looking at Keith crafft motors seems that most of them are not using a PCV Valve on one of the valve covers.

Just Purchased a quickfuel carburetor that doesn't have an additional vacuum input for one. So I was thinking of getting rid of My PCV on my roush crate motor.

Would It be detrimental?

Thanks

I have a Keith Craft SB427 and it did not come with a PCV. I have since added one due to a couple of issues:

1. Engine oil mist leaking past the breathers was making a MESS of my engine compartment.
2. Using oil at the rate of a quart every 500 miles.

After adding a PCV valve (nice hidden one in a billet aluminum breather) both issues have been resolved. To obtain an additional vacuum port, just drill one of the bosses of your intake manifold or the base of the carb.

[tirod]

Ok, history: the PCV was made mandatory in '68. Until then most didn't. They used a simple valve cover breather, the Chevy tube with cap in the front of the motor was very common, the older Y block Ford had a pipe hanging down slant cut to help the vapor escape.

In strict engine terms, a PCV isn't necessary at all. What is necessary is some way to let crankcase vapors out - even a motor with 5% leak down means it's pumping 5% of the CID out past the rings. The racing Shelbys used a tall tube and cap on each valve cover to get it out.

A PCV is for emissions - it's a spring loaded valve that allows the vapor to escape thru the induction system, set up properly, it won't vacuum the crankcase at all. At high flow rates some close off, and if blowby is really bad, it still pressurizes the crankcase.

Since most laws are predicated on the statuatory age of the motor, with the engine year being the most significant, if it's a post '68 block, it will have a PCV. Titling it as a '65 may not help if that state lays claim to the later engine requiring all it's emissions devices. That should be cleared up first before making a decision.

Most crate motor builders don't have a PCV in the system simply because they have no idea whether you are using it for race or street. "They left it off." means nothing about whether you need it. Not all motors use one, either, some use the CCV system, which is nothing more than a small orifice left open and plumbed to the intake. With that arrangement, the valve cover breathing is routed back to the air cleaner and if high pressures are encountered, the vapor passes thru the filter into the motor.

On worn motors, it dumps a lot of oil on the filter, which the factory cares less about. Science it out which way you are required to go, if necessary, then choose one. If you do choose to go for an active system to keep crankcase pressures low, expect expense out of proportion to the few hp freed up at high rpms. It's another race part that almost never pays its way on the street.

[D111]

Ended up getting too nice filtered breathers for the valve covers. off with the PCV for now seems to run beautiful, can always put it back on later and Drill a hole into the intake manifold which I do not feel like doing at this point being that I would have to remove the intake manifold to do so I believe.

I will have to make it up to the environment by going Greener in some other area

Thank you much for all the Responses

[blykins]

Just watch out for mist out of the breathers under a full throttle run. If you do have any blow-by, it will show up there.

How does the carb feel?

[D111]

Originally Posted by blykins

-
How does the carb feel?

Just came back from a ride feels great, the Carburetor is on there as you sent It to me Brent,Starts right up didn't even have to adjust the idle The bowls are sitting about three quarters full.
When I come up to a light the idle goes Very slowly down from about 1000 rpms to 800.

It feels way better than the street avenger when I hit it the front jumps right Up And the tires feel like They are about to rip off the Rims

Only slight thing I notice is when slowing down and downshifting it seems to have a slight tugging nothing much .

[Hydramada]

Originally Posted by D111

Ended up getting too nice filtered breathers for the valve covers. off with the PCV for now seems to run beautiful, can always put it back on later and Drill a hole into the intake manifold which I do not feel like doing at this point being that I would have to remove the intake manifold to do so I believe.

I will have to make it up to the environment by going Greener in some other area

Thank you much for all the Responses

Just keep an eye on your valve covers for an oil film and definitely watch your oil consumption for a few months.