Im not sure how all this works so I'm asking here......finally.

My PCV valve was buzzing/rattling so I gutted it removing the inner workings and put it back on....is that a no no?

and...could I just delete it all-together since I already have a breather on both valve covers? Is having two breathers AND the PCV overkill/bad in anyway?

Thanks in advance..

depends on the application.
Here's a bunch to read.
http://en.wikipedia.org/wiki/PCV_valve

Funny...I JUST read that about a half hour ago. The engine has 600 mi. on it. Could I be creating a vac. leak/lean condition kind of situation running it like this? My idle does roam around a little, nothing too drastic.

Be gentle...I'm learning still

Shawn you ideally want a PCV on one side and a filtered breather on the other side so that air is drawn in one side to replace the blowby that is drawn down/over/up & out the other side.Blowby gasses are corrosive and impede the downward travel of the pistons. I would just replace your buzzing PCV and if your vacuum at idle requires a different PCV then yes find the correct one for your particular (I'm assuming non stock) app. A breather in each valve cover will keep the crankcase from being pressurized but will create no movement. Better yet is running a line(w the right valve) to a header collector so these gasses dont alter the precise air/fuel mixture in the carb but the blowby is still evacuated but this will greatly increase exhaust emissions

Gotcha...I'll replace the PCV valve and just replace the one breather with a "fill cap". The 340 is only slightly over stock, not a radical build at all.

Thanks for the replies fellas!!

Would having just two breathers create a lower vacuum reading situation than with having a PCV and a breather?

The PCV is a controlled vacuum lek.When you gut it its like having a vacuum line open.This has been discussed lots.We run just breathers on our motors.Mine is pretty much a race motor on the street and the kids 413 is almost 50 years old and running the OE rings.Neither has a problem without PCV.But running with a gutted PCV will make it lean.Rocky

Not to hijack, but to possibly add to the discussion.
I have a 3 nipple breather on one side with 1 going to the air cleaner, 1 to the return line and the other is plugged. On the other side I have a PCV going to the carb and a regular breather.
Is there a better way? Since low vacuum was mentioned, I have very low vacuum at idle, could I have a bad PCV? or is it my set up?
Thanks,
Jim

Jim, no hijack at all, we're here to help each other out. imnho you would want to cap the breather on the PCV side so the only entry point is on the opposite (from the pcv) bank which is your 3 nipple breather. fumes from the gas tank/fresh air from the aircleaner all will be drawn in/down/over/up & out the PCV on the oppposite bank.

If I read his post he gutted the PCV which will make vacuum low as it is just sucking air and making the car lean.Rocky

Lots of good replies and Jim, no worries....sometimes it's easier to get an answer that way since we're on the subject.

Thanks for the all help, It explains alot. I gutted the PCV valve when the engine was still in the tuning process, so I figured I had a vac leak somewhere the whole time. I've checked all over and found nothing.

Cant wait to get back home so I can start messin' with it.

Cheers fellas ....

Thanks,
So, I should use an oil filler cap eliminating the breather on the PCV side?
Is it OK to keep that 3rd lead off the 3 nipple breather plugged?
Will any of these things affect my vacuum at all?
Thanks again,
Jim

Your breather configuration will not effect idle vacuum mearsurement. A bad PCV could but not likely. If you are running a PCV you should only have one breather and it should be located in the opposite cover as the PCV. The third nipple(3/8") of the 3 nipple breather is for the original enclosed carb bowl vent, as I recall you are running a aftermarket carb without this vent line, the breather nipple should be plugged if not used for its intended purpose. The other line running back towards the rear(5/16") is the fuel tank vent line not a return line.
For 71’ this line ran back to the tank vapor separator located in the left rear wheel well.

Thanks, I have it the way you both describe. I just need a filler cap for the breather on the PCV side.
Jim

I don't see why you can't run 2 breathers. It can inhale through one and out the other. Or run 2 with a PCV.

The purpose of the PCV is to collect blow-by gases from the crankcase and meter it back to base of the carb for another round of combustion. If you are running a PCV, you need to maintain the flow of gases through the crankcase from one valve cover to the other. Placing a breather on the same side as the PVC defeats its purpose, you may as well not run a PCV at all.

[quote Placing a breather on the same side as the PVC defeats its purpose, you may as well not run a PCV at all.

---

Don't tell Ford that. My '77 F150 351M had a breather with a grommet in the center and a PCV in the grommet.

What about my slants? Only one valve cover to chose from.