I really don't like the idea of letting oil vapours run around willy-nilly inside of the double-walled shell. Seems like that would be asking for trouble. (In my opinion).

I agree with your comment about routing the vapors into the double-walled shell.  It just doesn't seem right and you would have to worry about what would build up in there.

I sure like the pictures you have included.  It makes everything so easy to understand.  I think your system is going to work great.

56D500boy - 2023-03-09 8:31 AM . Thanks for the detailed comments and suggestions Justin. Sounds like a plan.... But only *IF* there is an issue. And one way to find that out would be to carry on with Plan A and run the car for awhile, periodically checking the condition of the air cleaner element(s) for build up of oily residue, i.e. signs of blow-by. THEN if there is an issue, I can follow your suggestion, Plan B. :)

Chances are if the engine doesn't have excessive blow-by, it'll take a long time to clog a doubled-up filter that large enough to starve the engine if you aren't putting many miles on the car each year. Either way, I'd prefer your filter-element conversion over the oil bath.

Happy to give my input. I understand what I'm about to say gets deep into the weeds, but I know you and I both appreciate going down into those details, and you clearly are willing to go through the effort to improve your system. If your sole intent is to recycle the engine vapors once through combustion and out the exhaust pipes to remove fumes inside the cabin, your setup won't get you there. The oil-filler cap/breather will still vent vapors into the engine compartment and likely at a higher volume without the draft tube since the filler tube and breather have less resistance than your air cleaner modification with 3/8" hose. The primitive 1960's PCV system that Nathan describes--which you have essentially recreated with a smaller diameter hose--relies not on vacuum drawing out the crankcase vapors but on the vapors building up enough positive pressure in the crankcase to push into the air cleaner via a larger hose (usually 5/8" versus your 3/8"). The system does a poor job, just like the draft-tube system, of keeping the crankcase clear of contaminated vapors, positive pressure, and circulated with fresh air to cut down on deposits/sludge and to relieve gaskets/seals of pressure stresses. Your system will have the same internal physics as a draft-tube system with the benefit of venting one of the two breathers into the combustion process. If you choose to run this system as-built, I highly recommend you replace the PCV valve with a nipple with no check ball or modify the PCV valve to remove the check ball. Removing the check ball will increase the hose inside area and make it more likely the vapors will travel into the air cleaner versus venting through the oil-filler cap/breather. With the check ball in place further shrinking an already small hose diameter compared to the filler tube, the vapors will likely migrate through the filler breather versus your modification. Your current system does not require a PCV valve since that line has no vacuum applied that requires regulating.

To improve the primitive system, manufacturers started using a system that ran a hose from one breather into the air cleaner and added a vacuum hose from a PCV valve in the valve cover to manifold vacuum downstream the carburetor throttle plates. In this system, the purpose of the breather-to-air-cleaner line is reversed from yours: that line doesn't vent vapors into the air cleaner but draws filtered fresh air into the engine to replace the air that the manifold vacuum sucks out through the PCV valve in the valve cover. The PCV valve is required to regulate the vacuum signal. This system keeps contaminated crankcase vapors sucking into combustion, replaced with filtered fresh air, and the gaskets/seals free of pressure in a constant cycle. For a V8 system, the breather would be on one valve cover and the PCV valve on the opposite valve cover to promote a circular, thorough flow of air through the crankcase.

When I first bought our 1956 Dodge coupe, the poly 270 with 95K miles had a ton of blow-by that would come out of both the filler cap/breather and the draft tube. To cut down on the cabin vapors until I pulled the engine, I ditched the oil bath and modified the base of a new aftermarket paper filter air cleaner to fit on the 2-barrel carb. That base had an integrated 5/8" nipple. After measuring the filler tube and digging through parts catalogs, I found the Gates 31070 with an integrated 5/8" nipple was a perfect fit into the filler tube (https://www.jegs.com/i/Gates/465/31070/10002/-1). I ran a hose from that breather to the air cleaner nipple, essentially doing what you've done in venting vapors into the air cleaner. With this system, I saw about the same blow-by out of the draft tube but all the filler breather vapors captured into combustion.

If you want a vacuum-assisted PCV system, as I've already mentioned, you could either make a carb spacer or drill a hole in the right side of the intake plenum, tap for FPT, and screw in a nipple. You'd connect your PCV valve in the valley cover to this nipple for manifold vacuum. You'd abandon the pipe you've installed in the air cleaner. In this system, the manifold vacuum would suck the vapors through the PCV valve, and fresh air would draw into the crankcase via the oil-filler breather. It wouldn't promote ideal circulation since the active flow won't go through the valve cover, down through the crank case, and up through the opposite valve cover, but it would create a circular flow at least in the top of the crankcase. If you wanted to filter the air entering the crankcase more so than the breather filter element allows, you could use a breather like the Gates 31070 and run a hose to the nipple of your air cleaner modification.

I sum, if your ultimate desire is to remove all vapors from the cabin, you need a vacuum-assisted PCV system. If your ultimate desire is to also keep the engine as free of sludge and pressure build-up as possible, you need a vacuum-assisted PCV system. If your desire is to decrease the vapors in the cabin but not remove them completely, your current modification (with the PCV check ball removed) will move in that direction more so than the draft tube, but you'll still get vapors venting from the filler breather.

We might be talking about a different spacer. I'm referring to a spacer that has the correct front to back bolt pattern for the WCFB but requires the holes be relocated inward like the image I quickly edited. There isn't enough material to move the holes inward. If the spacer is made for a Holley/AFB baseplate, which I now see it likely is, then there won't be any issue since the WCFB holes would be in the main body of the spacer and not the ears as you point out.

Dave, if the spacer is a Holley/AFB, you could simply scribe the WCFB holes onto the spacer, center-punch and drill them, and cut off the ears to clean up the perimeter. I'm not sure if you've messed with phenolic plastic before, but use an awl or similar sharp point to push a center-punch, but don't use a hammer to make the punch since the plastic can crack. When drilling, I'd use three steps starting with a 3/16" bit up to the finished bore. While it sounds odd, use cutting oil with the drill speed at a moderate rpm to make the cuts, and go slow letting the bit do the cutting without digging in quickly. This method will keep the plastic from melting, the bit from screwing in, and will result in cleaner bores. When you're done drilling the holes, use a countersink bit held between your fingers to lightly chamfer both sides of the bore. Presto! Custom PCV WCFB spacer.

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