[68lemans462]

Inspired by mchell's recent post on "air flow" and needing an air cleaner, I bought a new dual snorkel air cleaner setup. I love the look and the engine really seems to like it performance wise.

I connected the valve cover breather to the air cleaner, as pictured. On the other side there is another breather + the stock pcv hose to carb.. In talking with others there was concern about the absence of air "pull" in the pcv system from the valve cover due to the 14" cap. What are your concerns with this if any and or how can it be improved upon? Thanks

[lust4speed]

The breather with the vent tube is totally separate from the PCV system and definitely not dependent upon availability of any negative pressure in the air cleaner. Figure a majority of us here have straight vents not going to the air cleaner and simply open to ambient air pressure with absolutely no problem. The tube does allow the valve cover to stay a little cleaner and also allows any fumes to be mostly inhaled by the carb and burned in the combustion process. As long as the PCV hose still goes to manifold vacuum you are good.

[78w72]

yeah that tube is doing nothing with the smaller lid & open air cleaner... same for the dual snorkels, with the open lid they are not functioning at all, all the air is going into the open air cleaner. that isnt a bad thing aside from pulling all warm air from the engine bay, but it does have more open area than just the snorkel ends.

to make the vent tube function you'd want a full lid which will also draw air from the snorkels although still warm air. if you don't care about originality, i'd just get rid of the v/c vent tube & get an open breather as mentioned above, the pcv will function as it should & you can keep the smaller lid for a little better air flow.

[Formulajones]

Like mentioned, that breather on the passenger valve cover isn't reliant on any pressure from the air cleaner, so you can run it like you have it, or just put a regular breather in the valve cover that vents to open air. Either way works.

You have a PCV hooked up in the other valve cover running to manifold vacuum, you're good to go.


Now at the track you can switch from the stock full lid to the dome lid you have in your picture and see how the car responds. Those dome style lids have always worked really good for me.

You could even go a step further since you have a GTO hood and a 68, you could buy the 68 style pan and seal for the hood, open the scoops for fresh outside air and see if the car likes it, and still look stock. Just a thought.

[grandam1979]

Can you take another picture with the air cleaner off? Just want to see how you have pcv hooked up.

[68lemans462]

Good call Larry. I previously had a crummy El Cheapo Air cleaner ( with the hated K&N lid) that I ran around town with and at the drag strip I was running no air cleaner. This new setup seems to work better than either in all conditions esp at WOT

[NeighborsComplaint]

It's fine the way it is. You have a venturi effect with low pressure at the air filter that will draw the fumes out. Really isn't any different than with full lid in place.

[Tom Vaught]

The flow may not go into the carb airhorn under some modes of high speed but would be drawn from the Air Cleaner for the PCV/Valve Cover. In either case the air flow whether going into the engine or getting flushed under the chassis, (The engine will have a POSITIVE PRESSURE in the PCV/Valve Cover Hose/oil pan during WOT conditions.
That is the PUSH Mode of the system. Maybe not as Emissions friendly but should at least keep oil off the firewall with the small filter on the air cleaner ring.

Tom V.

[389]

You want to pick up filtered air behind the filter and run that to the passenger side valve cover. Make sure there are no other openings in that valve cover. Next run the PVC valve into the drivers side valve cover and pull all the gasses into the air cleaner, carb then out the tail pipe...

You would be better off using the correct lid to that air cleaner so you can take advantage of the velocity that was built into that air cleaners snorkels...

[Tom Vaught]

Originally Posted by 389

You want to pick up filtered air behind the filter and run that to the passenger side valve cover. Make sure there are no other openings in that valve cover. Next run the PVC valve into the drivers side valve cover and pull all the gasses into the air cleaner, carb then out the tail pipe...

You would be better off using the correct lid to that air cleaner so you can take advantage of the velocity that was built into that air cleaners snorkels...

I do not agree with this flow path.

Originally Posted by 389

You want to pick up filtered air behind the filter and run that to the passenger side valve cover. Make sure there are no other openings in that valve cover. .

If the engine is worn, having the push side hose installed after the normal 14" air filter will allow raw oil and fumes directly into the engine with the potential to reduce effective sparkplug life and possible oil fouling. The small filter on the air cleaner outer ring eliminates any road dirt/ trash from entering the hose to the passenger side valve cover. You will remove one filter in the two filter system but now allow raw oil directly into the carb (after the 14" air filter if the crankcase is pressurized (under WOT Modes).

Nor this flow routing.

Originally Posted by 389

Next run the PVC valve into the drivers side valve cover and pull all the gasses into the air cleaner, carb then out the tail pipe...

You just took the Intake Manifold Vacuum out of the normal driving modes so now the only way the PCV will work is under high suction modes in the Air filter area under high rpm modes.

Install the parts the way the Pontiac Engineers and other OEMs designed the PCV System and you will be fine.

Tom V.