Breather recovery canister with PCV

[bjhines]

I have been using this entire V8 track car project to hone new skills and justify buying a few neat tools. This is one of my first functional TIG welding projects. I am by no means a practiced TIG welder. I have been learning to focus and control the heat to allow welding thin(0.065") aluminum tubing. This project was done with a base model TIG torch with control on the handle. I have since purchased a pedal controller and hope it pays off in the future. I found it very difficult to use the thumb wheel on this particular project.

 

The goal of this system is to provide the required catch-can volume for spill control and to provide a functioning PCV system. The engine is a mildly cammed 327 SBC. It should provide good vacuum in the paddock and on decel. The system consists of 2 valve cover breathers connected to 5/8" hoses that TEE and run down to the quart capacity catch can. The baffled can has a 3/8" vacuum takeoff that is connected to a 3/8" hose, PCV valve, and then to the carby's manifold vac port. The catch can has an additional PCV valve mounted in the top to allow overpressure release while closing to maintain available vacuum.

 

I use a several techniques to fabricate the parts for the canister. I used 6061 grade 0.065" plate and 0.065"- 3" dia tubing. I made 3 identical dished covers for the top bottom and baffle. I rough cut 3 disks and used the flaring die to dish them. I then used the center hole to chuck them all stacked onto a bolt and lathe-turn them down to diameter to fit inside the 3" tubing. I made a threaded NPT bung for the drain and a larger bung for the secondary PCVV grommet. I made a ribbed 5/8" hose nipple on the lathe and coped it to fit tangent on the 3" canister. I made a 3/8" barbed nipple for the vacuum port using a flaring tool.

 

 

 

Here is an iside picture of the baffle positioned above the 5/8" inlet post.

 

 

 

Bottom welded on and drain-bung attached.

 

 

 

Here it is installed in the car. You can see the 3/8" vacuum port sticking out above the baffle and the secondary PCVV in the top of the canister. The top PCVV opens to relieve pressure but seals closed to maintain available vacuum.

 

 

 

Here is the primary PCVV mounted in-line near the carby vacuum port. I turned the PCVV adaptor on the lathe and used O-rings and a lip to seal and lock it into place. The 3/8" connector is 3/8" tubing flared on both ends for retention. I purchased the elbow from the "Help section" at autozone. I cut it and turned the legs to make a "U"

[bjhines]

I found that all PCVV are not created equally. Some are highly restrictive. All are considered check-valves(one way), but some do not positively seal. Some of them have weighted check pintles that do not close easily when mounted upside down. Some of them do not open easily when right side up. I pulled dozens out of their packages to check flow and operation to get the results I wanted from the primary and secondary valves.

 

I wanted the primary PCVV to flow a moderate amount of air to maintain a quality idle with a mild cam while still generating decent vacuum on the crankcase. The secondary releif valve needs to flow as freely as possible(to relieve overpressure) and close easily with a positive seal to maintain vacuum.

Edited April 20, 2010 by bjhines