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valve cover breathers into new air cleaner
#1
I installed new chrome valve covers on my '71 coupe 302 2 barrell, along with a free flow chrome air cleaner My question is; what do I do with the breather hoses from the valve covers that use to go into the air cleaner ? Are ther caps that go onto the valve covers to cap off these hose ports?
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#2
timmurphy;13593 Wrote:I installed new chrome valve covers on my '71 coupe 302 2 barrell, along with a free flow chrome air cleaner My question is; what do I do with the breather hoses from the valve covers that use to go into the air cleaner ? Are ther caps that go onto the valve covers to cap off these hose ports?

if you look at the pic of my engine you can get these kind of breather caps for your valve covers. I have one on each side.



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Eric


[Image: a58hgh.jpg]
DRIVE IT DON'T STORE IT!
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#3
timmurphy;13593 Wrote:I installed new chrome valve covers on my '71 coupe 302 2 barrell, along with a free flow chrome air cleaner My question is; what do I do with the breather hoses from the valve covers that use to go into the air cleaner ? Are ther caps that go onto the valve covers to cap off these hose ports?

Many but not all air cleaner bases have a knock out where a barbed fitting can be installed to accept the valve cover breather hose. I highly recommend you keep the pcv system fully functional which includes connecting the valve cover breather to the air cleaner although many people run a pcv valve on one cover with just a breather cap on the other with no issues.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
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#4
TommyK;13647 Wrote:
timmurphy;13593 Wrote:I installed new chrome valve covers on my '71 coupe 302 2 barrell, along with a free flow chrome air cleaner My question is; what do I do with the breather hoses from the valve covers that use to go into the air cleaner ? Are ther caps that go onto the valve covers to cap off these hose ports?

Many but not all air cleaner bases have a knock out where a barbed fitting can be installed to accept the valve cover breather hose. I highly recommend you keep the pcv system fully functional which includes connecting the valve cover breather to the air cleaner although many people run a pcv valve on one cover with just a breather cap on the other with no issues.

Is there a good reason apart from legal issues to keep the Pcv valve hooked to the air cleaner.

Eric


[Image: a58hgh.jpg]
DRIVE IT DON'T STORE IT!
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#5
The PCV is an emissions device that allows the pressure and corrosive gasses in the crankcase to vent, without venting these harmful gasses to the environment. The directional valve is in place to prevent a backfire from spreading to the crankcase. In the event of a backfire into the intake manifold, the PCV is supposed to seal shut, preventing the flame front from traveling into the crankcase. Without this directional valve in place (and fully functional) a backfire could also cause a crankcase explosion.
All motors will experience some degree of Blowby. Even a freshly rebuilt motor can experience between 5-10% Blowby, as checked with a Leakdown test. (Blowby is not the only source of crankcase pressure however. Due to the reciprocation of the pistons there will be a build up of pressure due to the air not being able to flow as fast as the pistons are moving in the higher RPMs) Blowby of combustion gasses introduces fuel and other combustion by products into the crankcase. Raw fuel, moisture, and various acidic materials will all contaminate the engine oil. Moisture can also enter the crankcase due to condensation overnight.
The good news is that most of these contaminants are highly volatile, meaning they will vaporize at relatively low temps; around 200F. Once these contaminants and moisture have volatized though, they must be purged from the crankcase. This is where a crankcase ventilation system comes in.

[Image: 2zdx09d.png]
Yea,Tho i cruise through the valley of the shadow of rice,I will fear no Turbo,For Torque art with me.Thy rods and crankshaft,they comfort me. Big Grin Robert
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#6
72fastback;13669 Wrote:
TommyK;13647 Wrote:
timmurphy;13593 Wrote:I installed new chrome valve covers on my '71 coupe 302 2 barrell, along with a free flow chrome air cleaner My question is; what do I do with the breather hoses from the valve covers that use to go into the air cleaner ? Are ther caps that go onto the valve covers to cap off these hose ports?

Many but not all air cleaner bases have a knock out where a barbed fitting can be installed to accept the valve cover breather hose. I highly recommend you keep the pcv system fully functional which includes connecting the valve cover breather to the air cleaner although many people run a pcv valve on one cover with just a breather cap on the other with no issues.

Is there a good reason apart from legal issues to keep the Pcv valve hooked to the air cleaner.

Yes. The pcv system mitigates the potential for excessive crankcase pressure common in older or higher mileage vehicles which can cause oil leaks, piston ring blowby and even cause your dipstick to pop out under hard acceleration.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
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#7
goodpost

Thanks for the great information, guys. I thought all that stuff was just to keep the EPA guys happy on the design end. Now I know it has a real world purpose as well.

Doc

Doc

[Image: 6y14ea.jpg]

Project started 8-7-10
Completed: All new suspension, rebuilt 351C H Code bored .030 over with mild cam and intake, new 3.50 TracLok, custom exhaust system
Current "mini-project": interior upgrade Undecided
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#8
So what you are saying is that the breather caps you see in my pic are not enough the pcv valve would be better?

Eric


[Image: a58hgh.jpg]
DRIVE IT DON'T STORE IT!
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#9
72fastback;13698 Wrote:So what you are saying is that the breather caps you see in my pic are not enough the pcv valve would be better?
pcv would help pull pressure and contaminants out quicker

[Image: 2zdx09d.png]
Yea,Tho i cruise through the valley of the shadow of rice,I will fear no Turbo,For Torque art with me.Thy rods and crankshaft,they comfort me. Big Grin Robert
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#10
72fastback;13698 Wrote:So what you are saying is that the breather caps you see in my pic are not enough the pcv valve would be better?

I may have missed some one saying this if I did forgive me.
The PCV valve should be plumbed to the intake vacum port not the air cleaner.The PCV valve replaced the old down draft tube on older engines.This system burns the gasses that are created in the crank case.You WANT to have a vacum / circulation on the crank case.
If you look at the factory system and think about how it works it will help you to understand what is going on..
The factory system has the pcv located on one side of the engine it is plummed to the intake vacum port,thus creating suction.The check ball in the valve is pulled off of it's seat.This pulls the gasses from the crank case to be recycled through the fuel being burnt.In a good engine very little blow by etc...does not hurt your performance at all.
Well now that we are pulling on the crank case the flow has to come from some where.
On the opposite valve cover you will have a vent that on our cars goes back to the air cleaner and has a smaller air filter to allow filtered air to flow through the crank case.This give you your circulation.Fresh air in bad air out.
If you want to run an open air cleaner you can use a vented oil cap such as the one on Roys engine to filter the in comming air on one side.
It is a proven fact that race engines like crank case vacum,helps with ring seal.You will usually see two types of systems on race engines.
The first being the valve covers vented to the header collectors using divertor or one way valves.
The best system is the one using a driven vacum pump that is plumbed to the valve covers.
My hope is that I have not confused any one.I am a beleiver in the PCV valve.It will keep you from getting oil leaks and oil pooling up on your valave covers intake etc....

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