Ok guys. I’m installing a catch can. I’ve read the threads here from simple to complex. There is one thing I didn’t see explained and hopefully someone can shed light. Nturally aspirated engine. Basic catch can- I have seen VC-pcv (stock) to catchcan to manifold. I know this setup is acceptable and works. But some members who contributed to the catch can knowledge suggested this is better but didn’t mention why...VC-catchcan inlet then PCV on the outlet and finally manifold.

So question is...what is the difference between pcv valve before catchcan vs pcv valve after catchcan. What benefit is it offering other than keeping the oil off the pcv valve?

thanks folks.

 

Alright, no takers. After contemplating my initial question more the only thing I can surmise is this...with the pcv post oil catch can the response of the valve isn’t affected by the catch can and extra tubing length. Also, theoretically, less chance of the can ever having excess pressure during a backfire or by not having the can pressurized when in boost (except for whatever leaks past the valve)

On another note, I tried the autozone valve deezums referred to. Maybe mine was bad but it didn’t work. It rattled like a ball bearing in a tin can, had an extremely weak spring, and upside down ithe amount the internal piston was open was more than twice the amount of my stock new oem valve. The stock ecu didn’t like it and it caused a high idle condition. Idle would slowly creep up as well.

 

I've had my can setup the same way as yours for years without issue.
Different hose routing and brand of can (unbranded baffled can mounted where the charcoal canister used to be before I relocated it), but same connections.

also can confirm it does it's job, since mine does need a drain every once in a while.



In essence you're using it as an oil/air separator.

 

There are many threads on this if you do some more searching but the quick spoon feed that most people do is to drill and tap both vent lines with larger npt to jic adapters the cap the passanger side and run a single line off of the driver side vent. You will also want to put copper scrubbers inside the valve cover and drill out the hole inside the valve cover baffling. Ill look through my build thread to try to find a picture of the work i did to my valve cover.

 

I’ve done a ton of research and understand the breather/cv mods for bigger power. I was just curious about the pcv placement specifically based on my research. Feel free to post whatever pics you like though as more reference points are always great. Thanks!

 

Missed that you were non turbo my first time reading that. Your setup will be fine then when you are ready for more power just cap that side. Also i was not able to find the pictures of what i did but it is in the other catch can threads on here somewhere.