I have a 347 with valve covers that have breather ports on the left valve cover and a port for a oil fill cap with a hose port. My question is can I route both valve cover breathers to the port on the throttle body or do I use one valve cover breather?
If you are running a pcv, hook up just one on the oil port to the TB and make sure the other is sealed. If you don't have a pcv then two breathers will work, don't hook up anything to the TB.