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ive done rockwell harness tests on cam cores their ok it was all the newer lifters that are a joke. most cam corps use all the same blanks for cams. all the good lifter corps are gone



If the cam 's hardness is good but the lifters aren't then why does the cam lobe fail and not the lifter?




The cam and lifters need to be hard to prevent excessive wear, but the lifter has to be harder than the cam. The lifter has to be harder because it has load on one contact point all the time, where as the cams contact loaded point is spread all around the cams lobe.
Once the smooth contact surfaces are gone for different reasons (low zinc/pho, soft lobes, soft lifters, stuck lifters, improper break in, etc), friction increases and wear starts. That's when the harder lifter will rapidly take out the cam lobe.