1977-1979 Ford and Mercury - Two PCV valves?

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Two PCV valves?

Printed From: The Ford Torino Page
Category: Model Specific Forum
Forum Name: 1977-1979 Ford and Mercury
Forum Description: Technical discussion for 1977-1979 Ford and Mercury
URL: https://forum.grantorinosport.org/forum_posts.asp?TID=2735
Printed Date: 26-March-2026 at 3:54PM
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com

Topic: Two PCV valves?

Posted By: Turbo301
Subject: Two PCV valves?
Date Posted: 06-November-2009 at 2:33PM

When applying the carb cleaner the other day (didn't help the idle situation, but didn't hurt, either), I cleaned out the little filter and tube for the PCV valve at the rear of the passenger side valve cover. I later noticed that there was another PCV-looking valve (looked more like the PCV valves I'm used to) on the front of the driver's side valve cover, except this one feeds back into the base of the carburetor.

Do these cars (at least the 302s) have two PCV valves, and if so, why, and why does one go to the aircleaner and one to the carb?

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1977 Cougar XR7
1980 turbo Trans Am
2009 Pontiac G8 GT

Replies:

Posted By: Psquare75
Date Posted: 06-November-2009 at 3:07PM

That's definitely wrong.

With a full OEM setup..

pass side valve cover should be a PCV that runs to the front of the 2bbl carb.

the driver side valve cover should have a tube that runs to the air cleaner base.

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Paul
77 XR7 460/C6/3.00:1 *SOLD*
78 XR7 523/C6/3.5:1
79 F100 460/TKO500/3.25:1
'I also have some left over potatoes-I understand you can generate electricity from them'- Foote500

Posted By: Turbo301
Date Posted: 07-November-2009 at 11:08AM

But the aircleaner is unmodified and looks to be correct for the car, and it has a port for a PCV intake (along with filter and appropriate clip) at its back, to coincide with the rear passenger PCV port. Could it be that Canadian models had different emissions equipment and thus may be a bit different?

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1977 Cougar XR7
1980 turbo Trans Am
2009 Pontiac G8 GT

Posted By: Turbo301
Date Posted: 07-November-2009 at 11:14AM

I just consulted my newly-purchased Haynes manual, and it shows my setup; however, it labels the rear passenger vent as a "crankcase vent"... it sounds like it's the intake for the system, and the PCV valve is the exhaust, and the whole crankcase system is one big closed-loop. Interesting, I don't recall that kind of system being used on a GM car...

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1977 Cougar XR7
1980 turbo Trans Am
2009 Pontiac G8 GT

Posted By: mcford
Date Posted: 08-November-2009 at 1:59AM

same system on gm cars and mopars. its how the pcv system works.

Posted By: Psquare75
Date Posted: 08-November-2009 at 3:35AM

Right. I think you have the correct setup, just your descriptions threw me off.

My Olds has the same deal.

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Paul
77 XR7 460/C6/3.00:1 *SOLD*
78 XR7 523/C6/3.5:1
79 F100 460/TKO500/3.25:1
'I also have some left over potatoes-I understand you can generate electricity from them'- Foote500

Posted By: Turbo301
Date Posted: 09-November-2009 at 5:58AM

Sorry 'bout that, I wasn't quite sure how to describe them since I wasn't familiar with the closed-circuit design. Given that there was some oil at the base of the felt intake, it's probably a good thing I changed out the PCV valve :).

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1977 Cougar XR7
1980 turbo Trans Am
2009 Pontiac G8 GT