Boss 302R/302S Racing Breather Can
The factory Boss Mustang PCV system increases engine pressure and forces oil into the engine intake, especially during hard track driving. This results in a slight loss of horsepower and a reduction in engine oil at a time when they are needed the most.
One solution is to use an oil separator. This fits in-line with the PCV system and separates oil and oil vapor into a catch can and returns only “clean” air back into the engine. This is a good system, but no oil separator is perfect and some amount of oil or oil vapor will continue to be ingested through the intake via the PCV system.
Ford Racing Boss 302S with factory racing breather system.
The 302R and 302S factory race cars use a simple breather system that bypasses the PCV system altogether. This system ensures that no oil is ingested through the intake and should free a couple of ponies. The downsides of this system are that it is more expensive than an oil separator and it almost certainly violates any emission system do-not-tamper laws that many states have, which might cause some trouble when trying to get your safety or emissions inspection sticker.
Ford Racing does not sell this system as a kit. Rehagan Racing does sell this system as a kit, but it is spendy at $425. I put together my own kit for about $235 using OEM parts and high grade hoses and fittings. My version is overkill and a budget-minded person could do this (assuming the use of the core Peterson breather can), for about $150.
- (1) – Peterson Fluid Systems 08-0400 Breather Can with AN -12 Ports (about $90)
- (2) – Summit 220244B – AN -10 to AN -12 Adapter Black (about $10.25/ea.)
- (2) – Earl’s AT800110ERL – AN -10 ST Ano-Tuff Swivel-Seal Hose Ends (about $13.25/ea.)
- (2) – Fragola E-Z Clamp Hose End, -10 AN – Black (about $6.95/ea.)
- (1) – Earl’s 350610ERL – AN -10 PRO-LITE 350 HOSE 6 FOOT (about $57.95)
- (1) – Dorman 02253 – Bypass Cap Assortment (about $5.00) + (2) hose clamps to secure the caps.
- (1) – CR3Z-6A664-A – HOSE VENT ($9.44)
- (1) – 4L2Z-6762-AA – ELBOW, CRANKCASE VENT ($11.31)
1. Mount the breather can.
Find a suitable location on the firewall in the same area as the factory race cars. Measure and mark the location of the band clamp. Drill holes and mount band clamp with your choice of fastener. Since I don’t see the need to ever remove the band clamp, I chose to use rivets. Secure the breather can with the band clamp. Orient the ports as shown in the photo.
Notes: I found that removing the upper strut brace made access easier. I also removed the sound deadening material that was against the firewall. Honestly, I just don’t like the idea of moving blankets stapled around the engine bay. If you don’t remove it, you will have to cut or drill through it to mount the breather can. Finally, I had to remove one of the plastic pins that secures the cowl trim piece to the firewall to prevent interference with the breather can.
2. Make the hoses.
I would recommend first installing the hose ends that mate to the catch can. Connect the hose (using the AN -10 to AN -12 adapter) and tighten everything down (illustration 1). Then measure hose (twice) and cut (once) to proper length. Attach the two (2) plastic quick connectors from the driver’s side vent tube that is no longer needed. Attach the plastic connectors to the hose using the clamp-style hose ends. These connectors fit best into AN -10 hose, which is why I recommend using AN -10 hose and an adapter, rather than just using AN -12 hose. Hose and fittings are priced according to size, so using AN -10 hose and fittings are also less expensive.
Notes: Removing the plastic OEM quick connectors from the vent tube is somewhat difficult, because the tube is hard plastic. I don’t recommend trying to cut against the nipple, because any gouge could be a leak point. This is the technique I used. Cut the hose about 1″ from the tip of the nipple. Then make two cuts into the hose. Grab the tab you have just formed with a pair of needle nose pliers. Then, holding the tip of the tab firmly, roll the pliers so that you are tearing a ribbon out of the hose. If you can get the ribbon all the way to the end of the hose, the pressure fit of the hose will be released and the connector will be free. I took the photo before I had perfected my technique and I was just trying to pull downward, but the ribbon would break before getting to the end. Thin needle nose pliers work better and the rolling technique is the way to go.
3. Replace PCV valve.
On the passenger side of the engine, remove the PCV valve from the head and replace with the same style crankcase vent elbow that is found on the driver’s side. Alternately, you could remove the PCV valve assembly and discard the internal valve.
Notes: I don’t think this matters in any way, but the PCV valve (blue) and the crankcase vent elbow (black) are not exactly the same length.
4. Connect the hoses to the crankcase vents.
5. Cap the intake/vacuum nipples.
1. Put breather can in the “service position” by loosening the band clamp (11 mm nut) and tilting the breather can forward. Remove the cap by loosening the 11 mm top nut. Once the nut has broken loose, unscrew the whole cap to remove. THE NUT, THE CAP, AND THE THREADED ROD ARE CONNECTED. In fact, all of the guts are connected to the threaded rod (see photo 3). Use a turkey baster or mityvac to evacuate the oil.
2. At the bottom of the breather can, there is a tapped bung that holds the threaded post. The bung is stitch welded to the can in a way that allows oil to flow beneath it and into a tapped drain, which is the other way to service the breather can. Most of the race cars that I have observed have drain petcocks installed on the bottom of the cans.
3. This is the breather insert.
Notes and revisions:
Sharp eyes will notice that I used small rivets and washers to secure the band clamp. I had properly sized rivets set aside for the project, but once I got started, I realized that my rivet gun did not accommodate the shank of the large rivets. I will replace those soon, so that the breather can is properly secured. It is also possible to use a bracket that mounts to an existing hole in the firewall, so that no drilling is required.
One possible revision is to cut the top of the firewall for easier access for servicing the catch can. This can be seen in the photo of the factory setup at the top of the page. A more advanced revision that I am considering is getting the racing oil pan, tapping it, and running a drain from the breather can into the oil pan, which will make the breather system service free.
In 2013, I attended a Grand-Am CTSCC race and noticed that many of the top teams had begun to run TWO breather cans, one for each head. Instead of mounting to the firewall, the second can was mounted using a bracket.
I noticed both direct hose setups and crossed setups (breather can services opposite head).
The right side breather cans were mounted in the typical way (directly to the firewall), but the new left side cans got their own mount, which clears the firewall lip and should allow for easier servicing.
At appeared that all of the cans had petcocks for draining and all of the factory breather tube connections are now safety-wired.
This article will be posted in the Oil Separator Thread at trackmustangsonline.com. I have to thank a couple of the guys in that thread who did the first DIY versions of this system and were very generous with their experience and help. I recommend consulting that thread, because it will continue to be a current resource as new versions, revisions, updates, and ideas are shared about these systems.
Sound Tube Delete
This is the sound tube. Well, Ford calls it a sound enhancement pipe. Whatever. It’s an ugly plastic tube that runs from the intake to the firewall and is designed to enhance the engine sounds you hear in the cabin. I don’t like it.
Car companies are using various methods of enhancing engine sounds, including playing recordings of the engine through the speakers! Admittedly, this is largeley because they are making the cabins so quiet (something I appreciate at my age) that when you stomp on the loud pedal, you can’t hear anything. I understand the problem, but I just don’t like the solutions. They seem phony to me. It’s the automotive equivelant of putting cards in the spokes.
A second, more practical issue is that the sound tube passes over the oil dipstick, making it harder to check your oil. So, the sound pipe has to go.
1. Pull this out.
2. Buy this (it is widely available at most national auto parts stores). I paid $6.99.
3. Push it in. As you can see, my stereo installer had already drilled the firewall for the amplifier power cable. If I had done this mod sooner, it would have provided the perfect place to use a grommet without having to drill.
4. Go to Lowe’s and buy this.
5. Paint it. Push it on the intake nipple. Never worry about it again.
CPC Fuse Box Cover
This is embarrasing, because I tend to be a form-follows-function guy, but I actually bought a part that is strictly to dress-up the engine. I saw a Boss Mustang with one of these at a Cars & Coffee and I thought it looked like a great accent to the Boss intake manifold. It’s a CPC Fuse Box Cover that simply snaps over the existing fuse box cover. Simple as that. About $65.
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Hi Jimmy. Great write up on oil separator. Does the passenger PCV fitting just unscrew from the valve cover? There seems to be 2 tabs that lock into the valve cover that prevent me from turning the fitting.
I am installing a Morosso can, like your setup, capped intake manifold, passenger and driver valve covers run to a T into can and then the air intake from the Paxton connected to the other port on the Morroso. Will my connection to the air intake cause any issues?
Hi, Rick. Yes, the fitting just unscrews from the cover, after you have pushed-in the two tabs. Be careful, they aren’t very pliable and I broke one of the tabs when I removed mine.
As for your proposed setup, if I understand it correctly, the Moroso will act as a breather/catch can just like this setup, but I don’t know that a connection from the air intake to the can will do anything. Technically, that means the answer is no, it will not cause any issues, but you might want to consult with a good tuner or a good forum for advice about the best breather setup to use with a supercharger. Good luck and thanks for reading!