McLaren Valve Covers

Cannonball Garage Identifies Design Issue in McLaren V8 Valve Covers

The finding emerged early in our internal engine development program while technicians were performing a routine engine teardown. During inspection, the team discovered unusual wear marks on the underside of a factory valve cover. Further investigation revealed that the marks were caused by intermittent contact between the intake camshaft lobes and internal structural ribs inside the valve cover.

At first glance, the factory valve cover design appears clever and efficient. Both covers are designed as mirrored components, which simplifies manufacturing. But when we examined the internal structure more closely, we found that the stiffening ribs inside the covers were not properly mirrored.

Inside the factory valve covers are reinforcing ribs designed to accommodate the spacing differences between intake and exhaust camshaft lobes. On one cylinder bank the ribs are correctly positioned, but on the opposite bank the internal rib structure was not mirrored to match the camshaft geometry. As a result, the intake cam lobes can make contact with the plastic ribs.

While the contact is not immediately catastrophic, it gradually removes material from the valve cover. Because the covers are plastic, the removed material enters the engine environment.

It is not an isolated issue

Once that plastic material is removed, it has to go somewhere. Some of it is captured by filtration, but some circulates within the oiling system. Over time, that contamination may contribute to wear patterns that are often labeled as random or unexplained.

This condition was not isolated to a single engine.

Through our inspections, we’ve observed this same contact pattern consistently across every McLaren V8 engine we’ve disassembled. The same marks, the same wear patterns, and the same introduction of plastic debris into the oiling system.

Further analysis confirmed that the same valve cover design remains in use across multiple McLaren V8 platforms and model generations.

Oil Smoke from the Exhaust

On this episode of McLaren Engines 101, Ivan takes a deep dive into factory McLaren Technical Service Bulletins and uncovers a much larger issue hiding beneath the surface.

What started as a discussion about oil level readings and perimeter seal gaskets led us down a rabbit hole involving crankcase vacuum, oil scavenging efficiency, turbocharger oil return flow, and warped factory plastic valve covers.

Oil in the Spark Plug Tubes

In this video Ivan goes into another issue with the OEM valve covers. Oil in the spark plug tubes is one of those McLaren issues that usually gets discovered while chasing something else.

Most often, it starts with a wide-open-throttle misfire. You pull a coil pack and find oil dripping off the boot. Then you look down into the spark plug tube and see the plug sitting in a pool of oil.

That oil should not be there. After inspecting hundreds of McLaren valve covers, we found the same issue over and over again. The spark plug tube seal is supposed to engage around the outside of the tube, but in many cases, the seal lip ends up sitting on top of the tube instead. Once that happens, it cannot properly keep oil inside the valve cover.

The Cannonball Billet Aluminum Valve Covers

Rather than treating the issue as an isolated curiosity, we incorporated the discovery into our engineering development program. The result is a purpose-built solution: the CSO Billet Aluminum Valve Covers.

Machined from billet aluminum, the CSO valve covers eliminate the internal rib interference entirely, removing plastic from the equation and preventing camshaft contact. The design protects the engine’s oiling system while maintaining structural rigidity under high-performance conditions.

At Cannonball Garage, our engine development work isn’t just about making more power. It’s about understanding why components wear, how systems interact, and how small design decisions can have long-term consequences.

The Cannonball Billet Aluminum Valve Covers

Available soon

The CSO Billet Aluminum Valve Covers were developed directly from real-world inspection and engineering analysis rather than theoretical modeling.

This is what happens when you look deeper and ask why, it’s how real-world insights become engineered solutions.

The new valve covers are designed for McLaren V8 engines and will be available soon.

For more information about the CSO valve covers or Cannonball Garage’s McLaren engine development program, visit our engines page or contact the shop directly.

Find the two TSB’s from McLaren related to this issue below…