Valve cover breathers

[Senator Leahy]

Is there any disadvantage to not running the air line from the breather on the driver side to the air cleaner and just running a regular breather cap? Got the cast aluminum valve covers and I'm stuck on what breather and pcv valve to buy. Thanks

 

[bluefury361]

Is there any disadvantage to not running the air line from the breather on the driver side to the air cleaner and just running a regular breather cap? Got the cast aluminum valve covers and I'm stuck on what breather and pcv valve to buy. Thanks

The valve cover breather vented to the air filter is an emission's thing. It wont effect performance.

 

[1978 NYB]

I have a PCV valve on one side and breather going to the air cleaner on the other side just to keep oil residue off the engine and just recycling it through the carb so it doesn't make a mess.

 

[Senator Leahy]

Awesome. Thanks guys

 

[commando1]

The valve cover breather vented to the air filter is an emission's thing. It wont effect performance.

OK, gonna have to fight ya on this one. It' s called Positive Crankcase Ventilation for a reason.

Positive Crankcase Ventilation is not simply a "smog device", it is a good thing for total engine health. Removing blow-by, condensation, and the like with a PCV system will result in a much healthier engine than any passive breather or road-draft tube will accomplish.

A proper "type IV" system will include two lines connecting to the crankcase. One will be to manifold vacuum, and will contain the PCV valve proper. The other will be the fresh air supply. Ideally, it will pull from inside the area contained by the air filter (to provide a filtered fresh air source), and will have a small dedicated screen-type filter.

During normal operation, a small amount of crankcase air (and any excess pressure) will be drawn through the PCV valve into the intake manifold to be burned in the engine. The air will be replaced by the fresh air side. During unusual periods of low vacuum and/or excessive blow-by, the fresh air line can handle the excess load, and flow "backwards" into the carb to be burned by the engine.

 

[Senator Leahy]

I think I will still run things like they came from the factory with the breather from the valve cover to the air cleaner. there just a really badass breather on eBay right now that I want

 

[bluefury361]

OK, gonna have to fight ya on this one. It' s called Positive Crankcase Ventilation for a reason.


Positive Crankcase Ventilation is not simply a "smog device", it is a good thing for total engine health. Removing blow-by, condensation, and the like with a PCV system will result in a much healthier engine than any passive breather or road-draft tube will accomplish.

A proper "type IV" system will include two lines connecting to the crankcase. One will be to manifold vacuum, and will contain the PCV valve proper. The other will be the fresh air supply. Ideally, it will pull from inside the area contained by the air filter (to provide a filtered fresh air source), and will have a small dedicated screen-type filter.

During normal operation, a small amount of crankcase air (and any excess pressure) will be drawn through the PCV valve into the intake manifold to be burned in the engine. The air will be replaced by the fresh air side. During unusual periods of low vacuum and/or excessive blow-by, the fresh air line can handle the excess load, and flow "backwards" into the carb to be burned by the engine.

All true, As I stated, it's an emissions thing. Serves a good purpose. But still does not effect performance if the breather to air filter hose is removed. As long as a breather is in place. I thought that was the question.

 

[MrMoparCHP]

I think people are mixing the two different hoses.
The original poster was asking about the BREATHER hose and not the PCV hose.

I'm not sure when the hose on the breather cap that was tied to the air cleaner became standard but in 67 it was only on California cars, other cars had breather cap with no hose. In 67 it was referred to as the "Cleaner Air Package" (CAP) on California cars.


Alan

 

[ceebuddy]

The hose from the breather to the air cleaner usually does not draw filtered air since the hose is connected to a nipple on the air filter housing but outside of the filter element. The breather is the filter for the air entering the crankcase as it is drawn in to replace the air that is sucked out through the PCV valve.

If the PCV valve should clog, the pressure inside the crankcase would build up and fumes would exit through the breather. To avoid them getting into the air, they would instead go through the hose connected to the breather, be drawn into the carb via the air filter snorkel or housing and finally be burned in the engine.

So that hose is only an emissions-related precautionary measure in case of a PCV-valve obstruction.

 

[Senator Leahy]

Alrighty than. Good info everyone. But yeah I was just asking about the breather hose. I know the PCV has to be there. Thanks guys

 

[1978 NYB]

I've ran a breather cap on one side years ago.....it just makes a small mess. So I always run the hose into the air cleaner.

 

[commando1]