hex0rz
+1y
If your emissions checks visually when you go through to do emissions, then yes, if they know better, they will fail you if you have the Weber, etc.!
If they do a visual to pass you after failing for a waiver, then you will be screwed! But if its a rebuilt engine, and you do a conversion, and put on a new cat, just take to an auto place with a smog analyzer and have them de-tune it until the numbers are below requirements to pass and then go down and get it put through...
IF you think its the PCV valve you can check it by seeing if the ball rattles inside. If you are in any doubt spray it with some carb cleaner. BTW, you should of had a new one on it anyways since the engine is rebuilt!
Weber runs richer than a stock setup and I know you would fail emissions if you didnt get it tuned first!
IF you really want to, you might try and put a few bottles of heet in the tank and take it for a highway drive but first do some hard stopping and going so you slosh the tank around mixing the heet in.