67 gs 400 pcv?

Ryan474

Ryan474

Active Member
Hey huys I have a 67 buick gs 400. Motor was rebuilt and has a street cam. Now that a got a few miles on it I have not noticed only the driver side valve cover had a plugged port abs a filler/ breather cap. The breather cap drips some oil once in awhile, indicating to me a bit on pressure thats not being routed back into intake do to no pcv valve. Is this the norm for a 67 400 motor? And should i put a pcv valve on the plugged hole being its the only available spot or put a breather/ pcv valve combo?

Ryan


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The engine needs a PCV valve to evacuate water vapor and excess fuel vapor in the crankcase. It is not good to run it without a way to vacuum out the fumes.

There are enough bits and pieces of info in the Chassis Service Manual to reconstruct the original standard (non-California) PCV system. The left front valve cover hole gets the oil filler breather cap. The left rear hole remains plugged. It was used for a non-ventilated filler cap on California cars.

There should be a hole in the right valve cover at the center or rear to attach the hose going to the PCV valve. The PCV valve hose needs to be on the opposite valve cover from the intake breather. This will assure good vacuuming of fumes from across the crankcase.

The PCV valve mounts in a gromment in the intake manifold to the rear of the carb.
 
Ok that makes good sense but my car only has a breather filler on right valce cover and another plugged hole.. the left valve cover has no plugs at all..


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Several parts in the ‘67 PCV system for the 400 are one year only. That was the last year for the open type system and the breather/filler cap while it was the first year of the 400/430 series engines.

It took a while to recall from earlier posts that a ‘68 430 from a Riviera is installed. There are a lot of differences in the PCV components between ‘67 and ‘68. Without knowing what combination of ‘67, ‘68, and aftermarket parts are in use, it’s hard to tell what you have to work with. For example, ports to connect the PCV hoses may not be there any more.
 
I did some more research and found a guy at local car show that looked at my car and told my buick engineered the pcv on back side of intake behind the carb. The driver side was designed with the filler/ breather to pull fresh air in. This is how my car is currently set up. So from what he recalls my car is set up correctly and that the 67 valve covers did not have any holes on passenger side valve covers. I attached some pictures of my engine.
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The pictures help. There was confusion as to what is the left and what is the right side of the engine.

The PCV valve shows up in one of the pictures. What does the other end of the hose on the PCV valve connect to? The earlier post indicated there is no PCV valve.
 
Well i was unsure if that was the pcv valve on back of intake. I should have worded it differently.
The pcv valve is routed back to the base of the fuel injection vacuum port.


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I would agree with the car show guy that the correct components are in place and hooked up properly. It would not be a good idea to add a second PCV valve. When the valve is “closed” at idle, it still provides about 25% of the air used in the idle mixture. Adding even more air can result in rough idle.

There is test for the PCV system in the Chassis Service Manual on pg. 64-7. It may be a good idea to straighten out the rough running conditions and spark plug fouling issues first. Would be interesting to see if the breather cap residue decreases after other repairs are complete.
 
Got the ignition issue figured out but my breather is still puking oil…
I took the pcv valve out and gave it a shake and heard the ball moving around so its not stuck…

Ryan


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