Mike Murphy

^^ This

Mike Murphy

I think the IMS tensioner / chain ramp is the one that cannot be replaced without splitting the case on the 5-chain engine, correct?

sublm8

correct. Other large chain ramps can be replaced, however I question the utility of this as I and other owners have been able to get back to spec without replacing these. They don’t appear to impact cam deviation and they are quite large and unlikely to wear through, at least based on my research and observation. On my engine there was some wear but none of the visible pitting that affects the small cam chain pads.

Viper1000

Sorry for the stupid question but then why do they fall apart? Is it a different one?

sublm8

They just wear over time. You’ll see the center groove. When you look at them side-by-side w the cam pads you can see how much larger the surface area is and how the wear pattern is different as a result.

The four cam pads pit as they are smaller and under dynamic tension as the variocam actuator does its thing. Theory that the original material was inferior and new pads are better, unsure how accurate that is.

also you can’t visualize the IMS chain pads, so those I can’t speak to, but as noted there’s no way to access anyway. They are smaller and potentially a debris source. Nothing a mortal can do anything about without $$$.

De Jeeper

Those longer guides for the long chains and ims chain r a guide for the chain slack to ride against. The chain tensioners keep the chains tight. On the 2 small chains, variocam (can timing) the pads on the actuators push on the chain itself to create tension. This is why they wear faster and chunk.