Originally Posted By: Ducked
Originally Posted By: ka9mnx
Most cam failures in the 90's was later discovered to be with inferior camshaft and lifter materials and hardening. Present day failures are attributed to import lifters.
Ah, So if that's true, IOW there were failures, and there still are.
Doesn't entirely fit the "non-issue" line you came in with,
OK, cam and lifter failures are two different things. Obviously they relate to each other, but they come from different causes.
Most cam failures are caused by incorrect heat treating of wrong alloy selection and then poor surface hardening. The big failures (by numbers) were/are GM and Comp. Both were attributed to soft cores.
Lifters failures are related to one of three factors. Lifter face hardness, lifter face radial geometry, and poor bore fit. So something like the Delphi or Johnson lifters were well made and held to very tight tolerances. Then along came the off-shore copies ...
So the Aussies had/have to buy OEM lifters from the USA when GM and Ford were still building cars down under. Lifters were an expensive import item for the hot-rod community. So they got good at regrinding the faces and reusing them. Same quality metal throughout. They claim to be able to get three re-grinds and are still selling known good USA lifters as re-grinds around the world with decent results.
A cam will fail by wearing the nose off, usually through spalling. A lifter will fail by cupping or failing to spin. If a lifter skids (not spinning) it will die quickly. It's prolly dead in 100 Revolutions of the cam lobe, but if it starts spinning again, it'll limp along for a while. But the death knell is set.
The way you know which is which is by looking at the carnage. If the cam is flattened, but the lifter is mostly intact, you have a soft core /hardness issue. If the lifter is cupped or oddly worn, but the cam lobe looks about right, you have a bad lifter.
OEM spring pressures, even say Z-28 springs will not really stress a cam/lifter combo. But you start getting past say .550~.580 lift on a BBC (fairly mild hot cam) and say 350#s over the nose to control valve float above 5,000 RPM and you are goinna stress the materials. If they are not right, it'll die. >1,000 PPM ZDDP is mandatory as the spring pressures go up. Above these numbers and things just go sideways quicker, if not all correct.
Comp lost a lot of cam/lifter sets and did everything they could to blame the end user. Howards and Crower have had very, very few failures. Howard's offers a 5-year warranty if you buy their whole kit and follow instructions. Comp wouldn't do that if you paid them ...
Ford and Chrysler have had few cam/lifters failures running even their most aggressive factory grinds. Practically none of their daily driver combos have failed. And this is with average Joe doing spotty maintenance, etc. GM has not been so fortunate ...
So we need to know exactly what scenario you are interested in? I still will not buy much from Comp (mostly just rockers) and their other brands like Lunati. Howards or Crower - no question about their reliability as far as I'm concerned.
Oil pressure does not fix this. 60 PSI at 6,500 is plenty, more than enough. Bad oil and bad metallurgy will get you every time. It's up to the builder to get things right. Break-in right. Pop the valve covers and make sure every push rod is spinning as it should after initial fire-up. No start stop, or herky jerky allowed. It's either right, or shut it down and fix it ...
Cam on shim/bucket is a type of flat tappet. But not the traditional push-rod configuration that had all the issues ... OHC engines have different lube strategies and lighter valve trains, so they have milder spring pressures (no need to control as much inertia). Push-rod engines have cam lobes lubed by sling oil off the crank. Hit and miss at best ...