Emission questions

[Wobbles1971]

Not finding exact answers thru search or manuals, different set ups and stuff. So thought Id just drop a picture and try to get a quick answer from those in the know.

So I have my tube vent(1), pcv(2), and side vent(3) to deal with. As can tell I took off the emissions and smog pump. Now here is the back of my air box.

Basically I have the 2 ports on the air box tied up with the valve cover breather and the crankcase breather. Now my initial plan was to just route the side vent and center vent on the balance tube together to eliminate them without actually plugging. But the pcv valve vent is troubling me, not sure if its even needed without all the gadgets and not sure where to route it or if I can just plug it. Also, I was thinking about the crankcase vent coming off the block, I heard that it can be blocked but Ive also heard that its not a great idea, any thoughts? Btw, disregard my awesome "paint" job of the numbers on the back of the air box housing, was going to format the post differently.

[Arne]

Basically I have the 2 ports on the air box tied up with the valve cover breather and the crankcase breather. Now my initial plan was to just route the side vent and center vent on the balance tube together to eliminate them without actually plugging. But the pcv valve vent is troubling me, not sure if its even needed without all the gadgets and not sure where to route it or if I can just plug it. Also, I was thinking about the crankcase vent coming off the block, I heard that it can be blocked but Ive also heard that its not a great idea, any thoughts? Btw, disregard my awesome "paint" job of the numbers on the back of the air box housing, was going to format the post differently.

On my yellow '71 which has no smog pump, here's what I did.

• I still have the PCV (#2 on your balance tube picture) connected to the crankcase vent tube on the block.
• The port to the anti-backfire valve (#1 on your balance tube picture) is capped with a threaded pipe plug.
• The port on the end of the balance tube (#3) was already capped off when I got the manifold, and is also capped off from the factory on my other '71 which still has all its smog gear. Both use the same type of pipe plug as I used for the A/B valve port.
• The port on the airbox that goes to the smog pump (#1 in your second picture) is capped off. (A 3/4" rubber foot for a crutch or walking stick works well. That hole could also we welded up and the airbox painted for a clean look.)
• I am using the other port (#2) as intended, it is connected to the valve cover breather.

This all seems to work fine for my car. Hope it helps you.

[Wobbles1971]

I was going to run the crankcase (from the block) port to #1 in my second picture, glad I asked. I have a clear understanding of what you did and Im going to re-route stuff and dig thru some old hoses and get it set up the way you stated, sounds good. Can anyone chime in on their info regarding blocking off the crankcase tube? Like stated, Ive heard that it doesnt really matter much but then Ive also heard that the block needs to breath. The block breathing sounds logical to me Im just unsure of why I have heard conflicting reports in the past. Thanks Arne.