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RB26 - Damage to buckets and camshafts

Practical Engine Building

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Good day everyone!

I'm trying to find the root cause of this kind of damage after we installed camshafts and the recommended springs for the application on a RB26 (all from the same manufacturer). The cams "ate" the OEM bucket and you can see some damage on the ramp and nose of the camshafts lobe. About half the buckets were damage like this, and there is no sign of oil starvation in the head or in the Block rotating assembly.

Car is running Redline 10W-60 oil, rev limiter is set at 7800 and is pushing close to 600whp on my dyno. Valve clearance was adjusted with the spec of the cams manufacturer. Those are small lift 264deg cams.

Let me know if you ever saw that and what was the root cause so I can fix it and it doesn't happen again!

Attached Files

There are several things that come to mind, from failures on other engines, and it could be follower, camshaft, or both at fault -

Blocked oil squirters that should spray the tops of the followers, allowing the metal to metal contact.

A generous coating of anti-scuff/camshaft lubricant wasn't used, allowing metal to metal contact.

If, as they should be, NEW followers were fitted, they weren't actually genuine OEM, they were made of inferior material, and/or the heat treating was missed.

If the original/used followers were used - BAD practice* - the wear patterns disrupted the correct formation of the hydro-dynamic oil wedge/film and allowed metal to metal contact and, as soon as that occurred, rapid failure was assured.

The camshaft manufacturer, even if reputable, may have missed the heat treatment and/or other post-grinding process. Were these NEW camshafts, or exchange/reground, as some re-grinders are better than others when it comes to the quality of the grind and/or treating the cam lobes.

*With modern materials and finishing, one can often, even usually, get away with it, but...

How about valves and seats- did you do anything to them -valve job ?

Thank you for your input Gord. We did reuse the follower, as we usually do on other installs. We always visually inspect them but maybe they were starting to worn and we didn't catch that up. This is one of my theories as well about what could have happened.

Shota, we just performed the camshafts install. The head was rebuilt 4-5 years ago by another shop. However, I did check the valve to guide clearance and they are now out of spec so I'll probably have them replaced and perform a valve seat job.

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