The one on the rear.
BETTER NOT BE A PCV!
It should be a grommet and a fitting 45/ 90/ whatever elbow and hose- air can free flow both ways
A PCV is a check valve-air only one way-as it would be installed it would not LET REPLENISHMENT AIR flow from the breather to the valve cover
The REAL PCV is sucking all of the crappy Combustion Gasses out of the engine, it needs Fresh Air from the breather from the other Valve cover hole.
Think of it like this-
If you plugged the other hole with your thumb- the REAL PCV would eventually suck a vacuum on the whole engine (provided all seals are good).
When it sucks that vacuum, the engine idle starts running rough, WHY? WHY? WHY?
The suction is there! / The PARTIAL AIR FLOW TO THE CARB HAS STOPPED! (The other needed air comes thru the carb's throat) You just cut off some of the combustion air needed for idle!
These 2 air flows are sorta buddies, the engineers deemed that it needed so much air from each source to Idle and the PCV system operate correctly.
HERE"S A TRICK! IN THE FUTURE REMEMBER THE TRICK! DON"T ASSUME IT"S A PCV!
If you do have a PCV in the rear hole, take it out (this may have hindered your set up in the past)
Grind the metal bottom off of it until the guts all fall out!
NOW YOU HAVE AN ELBOW- NOT A PCV- It will fit in the grommet and now allow airflow! Yep sorta looks nice and fits well. However, it would make a feller like me check it out closer!
Leave the new Real PCV in the front hole untouched!
Are you learning stuff? Does it fall into place?
Friday, May 12th, 2017 AT 8:34 PM