Thread: Valve Cover Baffles

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I'm getting close to starting my rebuilt 350, and I have a simple question that I'm lacking the answer to. On my new valve covers I have 1 breather hole on each side. I was originally going to go with vavle covers without breather holes, but read an article about how that can gum up the internal area of the engine because of the build up of hydrocarbons. Would my best option be to run one side with a breather, and the other side with a PCV valve going to the back of the carb? I would have to run an open system because my air filter is open and does not have a place for a second hose. Also would the side with just the breather, be likely to get oily or residue from the escaping gasses on it? Thanks for any info!

Originally Posted by 67CamaroProject

I'm getting close to starting my rebuilt 350, and I have a simple question that I'm lacking the answer to. On my new valve covers I have 1 breather hole on each side. I was originally going to go with vavle covers without breather holes, but read an article about how that can gum up the internal area of the engine because of the build up of hydrocarbons. Would my best option be to run one side with a breather, and the other side with a PCV valve going to the back of the carb? I would have to run an open system because my air filter is open and does not have a place for a second hose. Also would the side with just the breather, be likely to get oily or residue from the escaping gasses on it? Thanks for any info!

I have an older 327 that had the draft tube that I used for the filtered air from under the air cleaner pan and used the oil fill in the intake for the pcv valve vacuum. I have had the valve covers of and clean as new. What ever proper pvc system you use and good oil and regualar changes you will have a clean vlave trian. Ed ke6bnl

Originally Posted by 67CamaroProject

m Also would the side with just the breather, be likely to get oily or residue from the escaping gasses on it?

When doing a breather on one side and a pcv on the other there is going to be a cross flow movement of air. In through the breather and out to the carb.

Denny has a great illustration somewhere.

if you plug one side, and vent the other to PCV, then you will have reduced crankcase pressure. This will help the rings to seal, help the front seal to seal, reduce oil past the valves, minimize air flow into the carb ( thru the PCV ), and any oil vapors or other crap will get burned.

However, if you vent the one side, then you will have dramatically increased airflow thru the carb ( a lean condition you will have to correct for ) dirt and crap flowing into the engine ( need to have a filter element breather ) and you are now venting all that crap into the atmoshpere which would otherwise burn.

My grandpa once siad the PCV was the only emissions invention which was worth keeping on an engine.

if you plug one side, and vent the other to PCV, then you will have reduced crankcase pressure. This will help the rings to seal, help the front seal to seal, reduce oil past the valves, minimize air flow into the carb ( thru the PCV ), and any oil vapors or other crap will get burned.

However, if you vent the one side, then you will have dramatically increased airflow thru the carb ( a lean condition you will have to correct for ) dirt and crap flowing into the engine ( need to have a filter element breather ) and you are now venting all that crap into the atmoshpere which would otherwise burn.
so in your opinion is it better to plug one side or put a breather on it?