pvc system

[sergio]

what are the pro's and con's of eliminating the pvc system on the nailhead? I have a '63 that I just pulled the valve covers on. The driver's (vented oil cap) side valvetrain was remarkably clean. The passenger's side with the PVC system was considerably dirtier. I am thinking of just venting the passenger side as well. Any thoughts? Thanks, Sergio

[YellowLark]

Well, you have a choice of conscience.

Nobody is going to inspect the smog controls on a 1963 car. That is three years older than even the California requirements.

On the other hand, the pcv valves were created to stop the really heavy pollution from the road-draft devices previously used. The standard argument that I have heard for many years is that a 1960 car causes more pollution just being parked than a post-1980 car does running.

So, rather than feel guilty, I would just clean out the hose and replace the pcv valve - its not much of your time or cost.

[the skylark]

Early PCV systems like yours pull crankcase fumes from one bank allowing fresh air into the other bank thru the vented cap to help pull the gases thru. Burning these gases does not harm anything in the engine, and is far less harmful to the environment. Newer models closed the system with unvented caps, and ran breather tubes/hoses to the air cleaner and breather filters. It sounds to me (as Yellowlark hinted) that the suction (PCV) side is not working on your 63, so the vented (cap) side is actually doing most if not all of the venting. Have you replaced the PCV valve? Check the whole vacuum circuit from the valve to the intake. Clogged hoses or clogged passages in the carburetor are not uncommon and would reduce or nullify the valves usefullness. Of course the gases that causes the sludge and pollution result from losses of combustion thru rings, seals, valve guides, etc. so there is the possibility of some mechanical reason for one bank to be cleaner, but it sounds to me in your case, the PCV has not always been working properly. Recommendations vary, but I like to change valves every couple of oil changes: valves are cheap, and clogged valves lead to clogging elsewhere and accelerated wear, so it's cheap insurance.
Hope this helps, and sorry about the length.
Dan "The Skylark62"
Merry CHRISTmas everyone, and Happy New Year!

[sergio]

Thanks for the good advice. The PCV valve looks quite old. I am going to replace it when I get the intake, valve covers and lifter valley cover back from the powder coater.