Breather System Installation - Breath Of Fresh Air - PHR Project Car

We didn't get 10 miles down the highway with our new 496-inch big-block before the smile faded and turned to a frown. The rearview mirror told the story: We were trailing a noxious cloud of oil smoke that made Kuwait's burning oilfields look like a Boy Scout camp fire. What the hey? Had we just turned a $7,500 motor into a boxful of industrial art Christmas ornaments? This was more than machine oil burning off a new exhaust; this was a serious Exxon Valdez.

We tried snugging those pleated cotton-gauze breathers. We tightened the valve cover bolts. We tried new valve cover breather grommets. We swapped on different breathers.We even tied old rags around the base of the breathers to stem the engine's flow of blood. But no dice. A small trickle of oil was dripping from both breathers onto the valve covers, and then onto the hot exhaust. And that was after making our best effort at placing the breather holes away from the pushrod oil holes at the top of the rockers. Were it not for the fact that we had seen this same problem in hundreds of other street cars, we would've been stymied. This is an extremely common occurrence on high-powered street machines, so when we went looking for a kit, we were shocked to find there isn't a single engineered system on the market.

Our Chevelle's breather system (clockwise from left) includes a breather tank from Summit, -6AN fitting with a 3/8-inch barb, custom plates for mounting the breather tank, 3/8-inch emission hose, two QFT valve cover breather clamps, two PCV breathers from Spectre Performance, a 3/8-inch OD "Y" barbed union, and tie-wraps.

Yet it's not like designing a breather system is hard, as we soon found out. Turns out, a lot of companies make the different pieces and parts, but you're on your own locating them and putting them together in a cohesive system. To that end, we hope this story will give you a major shortcut to solving your own oil-burning woes. As a side note, passive breather systems like ours are far more common on race cars, but their popularity is being quickly surpassed by more expensive crankcase evacuation systems, which have the additional benefit of a 20 to 40hp boost (typically) at the flywheel. They use a vacuum pump to pull the miasma of oil, air, and exhaust blow-by from the crankcase, then pump it into a breather reservoir like the one in this story. At some point, we may upgrade to an evac system, but for now we'll be happy without the massive smog tail.

When we finished, the sum of $351.28 had vanished, but we're confident you could make some substitutions to lower the price. If an alert vendor out there would like to package such a system under one part number, we'd be all too happy to give that soul some free ink, but until then, you can duplicate our system. And how well does it work? Since we put it on, we haven't had a single drop of oil hit our headers.

The 496ci BBC in our '68 Chevelle project car looked ready to rock after we stuffed it in, but it was a bleeder.	We decided early on that we wanted to use 3/8-inch vacuum hose everywhere, which caused our first problem. Most breathers (such as the popular Mopar style) use a larger nipple.	You'll need to find a good place for the breather tank so it won't interfere with anything else. Since we had removed the HVAC brick from the firewall, we had the perfect location.
This is an ant's eye view from the floor of the passenger seat, looking up at the firewall.	It turns out the crux of the oil leakage was at the breather grommet. These valve cover breather clamps from Quick Fuel Technologies are pricey at $62 each, but they work.	Our second obstacle was the hole size in the valve cover.
Inside the valve cover, you can see how the QFT breather clamp has a step that fits into the hole. The nut has a recess (not shown) to accept the step, thus locking the entire clamp into the hole.	We're almost there now. See how the clamp tightens around the breather, and the breather nipple faces up? We're glad we took the extra time to bead blast the breathers to match the valve covers.	The plumbing is next. You want to route the 3/8-inch emission hose from the breathers to the barbed "Y" fitting.
We've not seen a better valve cover gasket on the market than the Earl's Pressure Master Seals. A Viton rubber seal sandwiches a CNC-cut billet aluminum center.	Before clamping the passenger-side breather on, we topped off the missing oil with more Pennzoil 10W-30 Platinum synthetic.	Here's the finished breather system. It still provides plenty of filtered crankcase flow through the single breather element in the breather tank, but without the leaky oil mess.