Vacuum routing and PCV valve

[Rob Goblin]

So I want to run a PCV valve on my 84. As far as I can tell, there’s not one. The engine bay is pretty much just like I bought it. I fixed a water leak, changed the valve covers (the valve covers that came on the truck were circle track valve covers) and cleans the carb.

Yesterday, I was comparing both of my truck’s engine bays to try to figure out how to run vacuuming differently to incorporate the PCV valve on the 84. Where it’s ran on the carb of the 86 is where the brake booster is ran on the 84. Where the brake booster is ran on the 86 is omitted on the 84. There appears to be a bolt in that position in the 84. So is that nipple on the 86 carb something I should swap to the 84? I won’t be running the 86 engine. I’ll probably pull it and sell it or keep it in case I ever find a wagon. By the way, I really hate that intake on the 84. I will be pulling that eventually. If I need different pics, let me know.

84 engine bay:

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[Rob Goblin]

86 engine bay:

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[Rob Goblin]

86

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[RecklessWOT]

Well, the crankcase has to be vented somewhere or else you'd build up pressure and oil would be seeping from everywhere like an old model T. That engine bay looks way too clean for that to be the case. Whether or not there's actually a PCV valve in there is your choice, my guess is that a previous owner probably removed it and just put a breather or some other form of vent hose on it to prevent all those dirty burnt oil fumes from getting sucked back in through the intake. With those valve covers on there I'm guessing the guy was probably trying to tidy it up some and get rid of any excess vacuum crap that was running all over the place. That second oil cap might actually be a vent of some sort, because that's normally where you would put a breather. I suppose you could really just T into any vacuum line that's beefy enough to handle it.

Did the truck originally have power brakes? If someone converted it at one point in time they might have had to snag that line and figured it was more important than the PCV valve

 

[Rob Goblin]

The picture below is the type of valve covers that were on it, and it did blow oil everywhere. It still does but not as bad with the different valve covers on it. I recently cleaned the engine and it hasn’t been driven since. If it’s venting somewhere, I don’t see it. But you may be right. I’m clueless on this.

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[RecklessWOT]

Pop off that extra oil fill cap in back and find a breather that you can wedge in there (they sell ones that look like cone air filters but much smaller. Find one that has a rubber nipple that's roughly the same size as the oil fill plug hole and just wedge it in there. That's usually what I do in place of a PCV valve. That oil cap hole might be a little larger than a typical PCV hole, but I'm willing to bet that someone probably makes a breather for exactly that

 

[75gmck25]

The threaded port on the back of an Edelbrock is the brake booster port. You screw in a threaded adapter with a nipple for the line to the brake booster. It’s usually about a 6” long metal tube that is bent so it clears the air cleaner base. The large nipple on the center front of the Edelbrock is for the PVC valve.

The PCV valve can go in any port on top of the valve cover, and the PCV air “intake” goes in the opposite valve cover. You can buy an Edelbrock push-in filtered intake (like the 4403) from most Advance Auto parts or Autozone stores.

My stock steel valve covers had two holes in one cover (one was the filler cap) and one hole in the other cover. I now have aftermarket aluminum covers with only one hole each, so I have to fill oil through the PCV hole.

It’s a little hard to see the back port with the metal tube running to the brake booster in this picture, but the other lines are easy to see. This is the stock Quadrajet setup, but also works with an Edelbrock.

Bruce

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[82sbshortbed]

I just have 2 breather caps on the BBC 454 but. No pics

 

[ali_c20]

Breathers work, the pressure just has to go somewhere. Afaik a pcv system is better as it sucks out the oil vapor, blow by, moisture etc. keeps the oil clean and the motor happy.

 

[CoggedBelt75]

Has the issue been solved yet? I get confused on the simplest of stuff. So am I reading that there is a port in the rear but plugged off with a bolt. Or is it like this with an allen head bolt blocking it off?

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If so all that would be needed is a 1/4-18 NPT with a 3/8 barbed end. IMO, it would look cleaner with the boost in the rear and pcv in the front.

 

[Rob Goblin]

Has the issue been solved yet?

Not yet as I’m not driving it currently. It is a bolt. I may end up swapping carbs.