Corvair PCV modification for Individual Air Cleaners

When adding individual air cleaners, the dilemma of what to do about crank case ventilation is always a question. Some dump the gases outside the engine compartment to the street, others just buy a small K&N-type filter and put it on the end of the tube that was intended to go into the bottom of original air filter housing (as shown in the photo on the top right - click it to see a larger view). Still others go to a lot of expense to make the system work as originally intended yet have a spectacular show-quality presentation, as Herb Berkman did on the Yenko Stinger (YS-317) he built many years ago (the photo on the bottom right).

Here's another way that results in a PCV system that works properly, looks presentable, yet doesn't cost a lot of money.



click on pictures to enlarge


At Home Depot or Lowes (or any hardware store worth its salt), these 2" sewer line pipe connectors can be found. They cost between $3 and $4 each. At least two will be needed, but I picked up four so that all the air cleaners would be the same height on the Corsa engine. Four feet of 5/8" PCV hose and 2 feet of 3/8" fuel line were used to complete the project.



These 5/8" nylon barbed fittings were found at the local hardware store.......


along with this 5/8" Tee.

I used a Dremel tool with a cut-off disk and a grinding wheel to cut and finish the holes that are needed.


Cut notches in the rubber insert to accommodate the lugs on the carburetors.

With the rubber removed from the pipe connector, mark a circle a little smaller than the nylon fitting. With the cut-off wheel in your Dremel, make a crude hole on the connector as shown here. NOTE: Be sure to mount the connector on each carburetor before you cut the holes to mark them in the orientation that will work best for your set up. The tightening screws on the clamps need to end up in a location that will not interfere with throttle or choke linkages.


Using the grinding wheel, smooth and round the hole so that the nylon fitting slides in loosely.

With the rubber insert in place, mount the connector back on the carburetor with everything oriented properly, then mark the hole on the rubber with a Sharpie or pen. With the rubber removed, cut a hole SMALLER than the nylon fitting. The interference fit between the rubber and the fitting is what holds it in place.


Put the rubber back into the connector and insert the fitting as shown in this photo.


Put the air filter into the connector and then place everything on the carburetor, tighten the clamps and hook up the 5/8" hose.


After careful measuring, the end of the original PCV tube was cut to length with a pipe cutter. NOTE: 140 and 110 tubes are different. The 140 tube shown here did not have to otherwise be modified. The orifice tube will need to be relocated when using components from a 110 engine (see details below).

Here's a view of the passenger's side of the engine. The 5/8" hose runs from one side of the engine to the other with the 5/8" nylon Tee connecting the PCV tube and orifice A new 3/8" fuel line was run from the PCV orifice to the crossover/balance tube.


On the driver's side, the 5/8" hose is carefully routed to miss the various linkage pieces.

Completed system


Completed system

Fellow Corvair enthusiast, Chandler Bishop was my inspiration for doing the PCV system using this method. He installed the system on his 110 engine in a slightly different way.


On a 110 PCV tube, the orifice fitting is much further up on the tube and makes it very difficult, if not impossible, to route the hoses. Chandler removed the orifice fitting from its original location and relocated it a place closer the engine. He then cut the tube to length.


Here is a photo of the finished product ready to be installed.

On his first go-round, Chandler used 3/8" fittings and hose instead of the 5/8", only to discover that the smaller hose diameter doesn't accommodate the necessary flow required.


He then switched to 5/8" diameter hosing and used a 5/8" heater hose splice connection (instead of the nylon parts used above).
The finished system is very simple and effective. As shown here, the 5/8" hose runs to only one carburetor which eliminated the need for the tee and extra hosing.
Larry Starr of the Cactus Corvair Club shows us another variation on the topic:
Larry completed the project without modifying the PCV tube.   He fabricated carburetor adapters using parts from old Clark's air cleaners and some tubing. K&N filters were used - p/n RD-0610.