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Have you installed a covert closed PVC System ?


buick man
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Just thought I'd ask … so how many have successfully installed a Covert closed PVC system on their otherwise stock original nail heads with factory oil bath air cleaner … and if so how did you go about it … ?    Did you keep the original draft tube and used that within the scope of install process or did you remove it and plugged off at the valley cover … where did you install the PVC valve without molesting the valve cover or replacing the valve cover cap with an after market with the preinstalled port in the cap … ? 

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Remove road draft tube, use a grommet to install a PCV into the road draft tube hole in the valley cover, T off before brake booster check valve. That's the simplest way to go about it. If done properly, it can look as if it was intended to be there. However, you'd need to use some type of brass T fitting at the brake booster check valve if still using stock steel hard line. If you put it after the check valve, it will never open unless you pump your brakes a lot. Going to the air cleaner to complete the loop is another story, and probably best to tap into the air filter base at the back of the housing so you can see it... You would also have to tap and route a line from the valve cover to the air cleaner to complete the closed loop, with an appropriate baffle.

 

There's really no way to go about doing this without using a modified valve cover breather cap or air filter housing. At best you can run the PCV at the road draft as an open system... I'm sure you understand why a PCV system must be closed loop instead of open loop to actually benefit from a PCV system.

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… I was thinking the same thing about keeping the draft tube at it's location but internally blocking it off and tapping into the valley pan port and run a real route off from there to mount the PCV at a rear out of sight  yet accessible location … Install a carb base plate with the proper rear ports needed instead of going into the air cleaner  and leave the booster line alone … yes the ported non-vented valve cover cap would pose an obvious covert problem … still thinking …. - uncle dave

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Another approach that was used by '67 Chevy V-8s and the items should be in repro.  EASY to do, too.

 

This is how it attaches on a small block Chevy.  Remove the road draft tube.  In it's place there is a cone-shaped metal item which has a 5/16" bolt (about 3.5" long) that goes through it to the road rube's mount.  On this metal item, there's a nipple for a hose to connect to a pcv valve that attaches to the rear of the carb.  Needs a vac port on the carb that goes to manifold vacuum, below the throttle plates.  It all mounts horizontally and is pretty much incognito.  This preceded the valve cover pcv valve location.

 

One issue might be, with a carb not calibrated for such, is that you might need to close the throttle plates a bit to compensate for the "calibrated vacuum leak" the pcv valve will have.  Most of the pcv valves have the same flow rates, so getting one with the correct elbow on the top, or a straight nipple, can be more important.

 

Just some thoughts,

NTX5467

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Good input guys … one approach could be tapping into the rear of each valve cover covertly and then installing a small filter canister somewhere aside or deep behind the distributor area to filter the muck then continue with the line up to the base plate of the carb … so to have a closed positive system the gases need to be returned to the intake and also a means to create the vacuum within both the bottom end and top end of the engine to draw the vapor/gases and return them for secondary burning …. That is a good point regarding the carb and the gap of your typical plug R44's may need to be gaped a little larger, trick the dwell and perhaps a Blaster Coil installed as well … this procedure may help reduce no doubt lower end pressures and real main seal and pan gasket leaking to a major extent on existing components that may be seeping already … not to mention low idle gas outs within the general cabin and engine areas ….

Edited by buick man (see edit history)
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