<VV> blow-by

[Ernie Sanders]

I thought blow-by was the gases that get by the rings on the compression stroke and end up in the crankcase.  Old cars used to have a 'road tube' to vent it out.  Around the 50's they started to route it back into the carb to mix it into the intake and re-burn it.  After a short time they put a PCV valve on it so a backfire couldn't have a direct route into the crankcase and ignite the gases in the crankcase.  Ernie