Converting to... what? PCV is a very old acronym for one of the earliest attempts at controlling the emissions from auto engines. It stands for "Positive Crankcase Ventilation" and was developed in the 1950's. As is typical in our country, it was regulated into law in California first, since they have the perfect storm of population and geography to have a real smog problem in Los Angeles. Basically, the stinky byproducts of gasoline combustion were recycled and burned again to try to reduce their effect on the atmosphere, and not at all coincidentally, also make our garages not stink so badly of unburned hydrocarbons.
When I got Beck TD, the extremely worn engine was from a Volvo PV544, and it predated the PCV wonderfulness. When I updated the engine to one made in 1967 (Hey! Only 55 years old!) I kept the PV544 equipment because it looked more "vintage". Here's what it looked like:
Two things to note from the previous photo: the PV544 valve cover had the filler cap in the center, and that is valued in some circles for its vintage look. There was no PCV system, but there was a rudimentary system to evacuate fumes from the crankcase. That's the black tube in the lower center. It is variously called a "road tube" or because of its shape, a "Ram's Horn." The next photo shows the whole road tube after I modified it to fit the later B18 block. I had to cut and weld it to clear the cast-in boss at the back of the block. That work was reported in Part 44.
The road tube wasn't really an emissions device - it just dumps the gunk on the road. Or, more to the point, on the floor of your garage. I got tired of having to put a pan under Beck to catch the drips, so I elected to update to a PCV system. Here's what it looks like now.
You can see that I've replaced the valve cover with one that fills at the front, for clearance, and now there's an "oil trap" that attaches to a hose that carries the fumes across the engine to be sucked into the intake manifold. The PCV valve is the little silver canister in the tube, and that helps control engine vacuum under different load conditions.
I had some of the parts on hand, and Joe Lazenby sourced the other stuff I needed. Of course, the stuff I had was well-worn old parts, so some restoration was in order. Here's a before-and-after on the oil trap and the filler cap:
The valve cover was the worst, with some real rust damage on the back half. I glass-bead-blasted that, filled the worst of the pits with epoxy, sanded it smooth-ish, and after several coats of primer, paint and clear coat, it looked fine.
In the course of researching this project, Jake Roulstone, Joe Lazenby and I had several conversations about how this system actually works. It's really confusing, because Volvo changed the design several times, and there's plenty of misinformation on the web. At first, I thought I'd try to clear it all up, but there's actually a good resource at this link that makes it more clear, if you can figure out all the permutations:
If you look at the picture of my setup, I am missing the hose from #2 to the air filter, even though Joe supplied that hose to me. That's because the fancy air filters I just finished in Part 83 are too small to allow a fitting on the back for that hose. Instead, I used a small air filter directly on the oil filler. Note that this will work fine on the B18, but on the B20 the airflow direction is reversed, and doing this might make an oily mess. That's just a guess on my part, however, and Steve S. reports that this setup on his B20 stays clean.
Troy Nace and I took a long drive yesterday and it all worked fine. The engine did seem to have a bit of "lean surge" - not a surprise that I'd need to adjust the carbs a little after such a big change in the airflow. I enriched the carbs a tiny bit, and we'll see how that works in subsequent test drives. But I'm very happy to report that checking this morning showed that there were no drips or leaks from the new system. An easy project, and one worth doing.
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