Valve cover question
 

86 Chevy c-10, 305 v8. There is a small rubber pipe on my Right valve cover that runs to the air breather. Can someone tell me what it is? There has always been a little smoke that comes out of it. Is this normal. I know that if the trans modulator leaks, the fluid can travel to the engine head and burn up. Is it possible this is where the smoke is coming from. Thanks much

Re: Valve cover question
 

It's the air inlet for the PCV system. Providing your PCV valve is working correctly (and the engine is mechanically sound) that should be an inlet, the PCV should be evacuating the rest.

Should it be that way, not really, though I can't remember an OEM 305 I've owned that didn't do this to some extent. (iirc usually valve guides, but it's been a while)

Your modulator leak, if it's drawing fluid up the vacuum line, should be burning it in the engine. (smoke out the tailpipe)

Re: Valve cover question
 

Not sure about a 305, but on my 454 - one valve cover has pcv valve and hose to carburetor, the other valve cover has rubber grommet, metal fitting, fat hose to breather element in air cleaner.

Re: Valve cover question
 

oil/gas vapours
its to make blow by get reburned
but i've drivin with a 229v6.....smokin out there bad
even had to rout a heater hose,from there under the car

but i've seen it happen when i stop to get gas and check the oil