hi everyone.

i just got back from a short ride which included a short 65mph stint on the highway  (about 5 minutes).  i usually stick to "in town" or country cruising.

when i pulled in, i left the car running an popped the hood.  i have non-stock chrome valve covers with a breather cap/oil fill on the passenger side.  there was some smoke coming from the breather cap.  not a lot, but still noticeable, and there is some oil/exhaust residue on the underside of my hood in that area.   is this amount of smoke normal? i understand that it's a "breather" cap but not sure if i should see vapor coming from it.

thanks for any suggestions,

jeff

Check the filter that leads from the valve cover to the air cleaner assembly. Make sure the tube or the small breather filter isn't clogged. If it's clogged, the fumes have to go somewhere.

Also check the PCV valve to make sure it isn't clogged. Either of these can cause pressure build-up and create problems.

Perhaps condensation vapors ? if air humidity is high you collect a lot off
vapors in the engine . Stock they are aspired by the engine and "burned" with the gas...So the engine aspires air from air filter  , circulating it in the cranckcase  and  let it sucked by the carb who's supplying it tho the combustion chambers.... and trough the pipes ! First minute reving my vette ther is waterdrops and vapour  out of the side pipes ! ( gas may contain also some water , vaporised in the engine but again condensated in the exhausts.And those breather caps don't always seperate efficient oil vapour from air so in stock configuration it's " lubrificating" the valves as whe used to say it.On my boat engines there is even a "demister-centrifugal" vessel to separate oil from air , oil that is rerunning tho the crankcase , air to the air filter to be "eaten".
Ofcoarse a leaking head gasket can give water to oil .... vaporising .... but don't worry , see how it evolves ! Good luck !

I'm gonna guess you don't have all of the factory PCV stuff connected on the non-stock covers. If you've only got a valve cover with a breather on it, it's gonna blow a little smoke out while it's running. With the PCV valve conected from the carb to the valve cover on one side, the other side should have a metal tube going to the air cleaner base, with a small filter element in it. If all you have is a breather on the one v.c., you can expect a little more crankcase vapors to be escaping from it. It's not a problem unless it's blowing so much that you have oil dripping off the valve cover, which would indicate a worn engine, or a clogged PCV system. I'd suggest making sure you have the PCV valve in the driver's side cover, and it is working properly.

Joel,

you are correct.  i do not have all of the pcv stuff as stock.  i do  have the pcv valve from the carb hooked to the driver's side cover.  hopefully it's just like you said and it's just "more crankcase vapors escaping".  But me, being the world's biggest hypochondriac, got really scared when you said "worn engine". I'm always worrying about the engine. There is enough oil coming from the breather that i have clean it off the v.c when i do my motor detailing.  it isn't bad enough to drip off the v.c and drip on the exhaust manifold though.  i'm going to try to not worry too much and see how it goes. 

i'll keep you all posted.  Thanks!

The breather should be an air inlet into the engine.  The PCV sucks the fumes and air out of the crankcase.  Hence the name PCV, Positive Crankcase Ventilation system.

When a breather is not on the cover, there should be a inlet hose from the air cleaner or remotely located filter.   The air coming into the crankcase needs to be filtered, just as the air entering the carb.

By keeping vacuum applied at the PCV it maintains a constant flow of fresh air through the crankcase.  This pulls the vapor from previous condensation, and any blow by fumes from the crankcase.  Keeping the moisture and blow by gasses out of the crankcase helps keep the oil contaminates lower, and the oil last longer and does a better job while it's in there.

When the engine is shut off the hot engine may produce some fumes, and without the vacuum, it will allow some fumes to escape from the breather filter inlet.  This is not a problem.

WHen the engine is running it should not have fumes from the breather.  If it does there are a couple of possibilites.    One is the PCV valve and system is not pulling enough volume.  This could be from a clogged hose or passage the hose is connected to, or the PCV valve itself.   If the valve is clogged or is the wrong one it will not flow the correct rate.   If the valve fits and looks right it does not mean it's the correct one.  They have different flow rates.

The other possibility is the engine has excess blow by past the piston rings.  This condition will produce more fumes than the PCV can pull out, so it exits the breather filter inlet.

The PCV valve is really a calibrated vacuum leak.   Different ratings will change the air leak into the fuel system, and change the fuel mixture.   This could require a readjustment of the carb.

At idle the PCV has a lot of vacuum, and it's internal valve is pulled against a spring.  The pull is quite large, and pulls the internal valve almost closed reducing the air flow. 

As the throttle is opened, the manifold vacuum drops.  This drops vacuum to the PCV and creates less tension on the valve spring.  The  spring pushes the valve back open a bit, and the air flow increases along with increased air flow into the engine.  Ideally, the air flows always match if the correct valve is used.

The PCV valve also has a feature that when the engine backfires in the intake, it pressure forces the valve to shut completely.  This prevents the backfire from reaching the crankcase, and causing problems there.

It's actually better for the car to have a functioning PCV system.