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Hi Alex,
I have tried several of the coating materials on this type surface with mixed results. With Alfa's with the cast camshafts, that becomes the NEXT problem. Cam surface is too soft. The DLC coating is applied to the follower (or whatever) after hardening, and provides a very slick surface. It does not cushion or reduce pressure on the cam lobe. I'm not sure, but I don't think DLC can be used on cast iron due to porosity. I looked into this once, but remember there was a problem.
However, the followers, correctly hardened and coated, would be better than uncoated, for any application.
Just my opinion.
 

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Diamond coated? would that not make it a grinding stone?
 

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But on the other hand German made tappets might be a whole lot better with or with out a coating.
 

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The DLC is a clear coating, called "diamond-like-coating" as it is almost as hard as diamond. Not a grit or cutting material. VERY thin. It possibly might become a cutting material in porous materials like cast iron, I don't know. Used on friction surfaces to make them wear resistant and slippery.
Some year ago, I read about this as I was considering it on an Alfa crankshaft. I did not follow through, but would be interested on actual users comments.
 

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Is there a reason why a Teflon coating couldn't work? If it's applied to both the cam lobe and the bucket, with decent oil supply, the friction should be reduced and component life increased.
Or am I missing something?
 

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But Mad North-Northwest
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Teflon's low friction but too soft.
 

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Gubi's right, moreover, we have found teflon plays havoc inside engines. Something to be avoided.
 

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On the "ZDDP issue": I just did a valve clearance check on my engine that has about 50k miles now. I've been using Castrol GTX, no additives or supplements and noted virtually zero cam lobe or tappet wear. So my question is, outside of all the talk and banter going on around muscle car sites and such is there anyone here who has actually experienced or seen excessive wear or impending destruction due to motor oil reformulation?

Since the Alfa tappets are partially submerged in the cam housing oil bath they probably aren't a good bell-weather for this sort of thing but how about anyone with HP pushrod V8's using splash lubed cam and tappet interfaces. Has there been an actual problem or is it just a lot of talk so far? How about motorcycle owners?
 

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This has been posted on the BB before, and I have used it as a good example a few times. Another example I always throw away in disgust are the ball end Ferrari valve adjustors that touch the valve stem tip on single cam Ferrari V12's. These have been showing metal transfer issues for many many years, ZDDP or not. Excess clearance first ruins the adjuster ball tip, then the valve tip. Agghh! New adjustors are superior in material and hardening than old. I still check each and every one, replacing as necessary. Those that use Valvoline racing 20-50, and or other high ZDDP oils, come out better off than those that do not.
From my experience.
 

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