The PV vale is pretty much necessary for proper street operation. Blowby gases will build up in the crankcase, and eventually cause some obnoxious problems. Not the thing to worry about, now. It can cause the car tostall on opening the throttles, if you are too rich. It would stumble, maybe cough, and black smoke would precede the stall. If it stalls immediately upon opening the throttle, and there is no reamble, no stumble, just a sudden stall, she's too lean. This is not necessarily due to a lean idle; an improper accelerator pump setting or squirter can also cause this. The transition from idle to any other circuit in the carb, requires this shot of fuel to cover the sudden introduction of additional air. Four corner idle circuits can be tricky to tune, and the float level definitely needs to be adjusted. As stated, the best fuel level is at the absolute bottom of the sight plug, and should be the same on both primary and secondary sides. Try moving the idle mixture screws out 1/4 turn on all 4 corners, and see if the stall goes away. This is realy where you need to start, after confirming that there are no vacuum leaks around the carb base and adapter plate. After you make the stall go away, then you can properly tune the carb.
