Aluminum Timing Chain Ramp

[carrooth]

I have my muffler and heat exchangers off. While off I have adjusted valves and rebuilt the old open reservoir tensioners.

In another thread regarding the tensioner John Walker recommended changing the plastic timing chain ramps as they can break and do bad things. Sounded like a great idea while I was in there. Only problem is I have aluminum ramps with a plastic cap on top. Apparently these ramps and the open reservoir tensioners were only in 65-66 911's.

Are the plastic faced aluminum ramps prone to failure similar to the solid plastic ramps? Are plastic ramps interchangeable with the aluminum ramps?

Thanks, Jay