cam/lifter rockwell ?

[rod]

my friend just finished a 496 BBC. had a solid lifter cam. not long after break-in a lobe failure occurred. he had the cam nitrided, so it would last a long time. there is a tech college near him and he had the cam and a lifter checked for hardness. the lifter came in about 54 RC and the cam between 34 and 39.
what we do not know is 1. what is a normal figure for these two pieces, and 2. should the cam be the same hardness as the lifter.

any thoughts will be appreciated.

thanks rod in AZ

[Terry Cain]

That sounds about right for lifters but, kinda soft for cam. How much spring pressure, open and seat? High Zinc oil correct? I'm guessing roller rockers?

[Marty Buth]

Nitriding usually yields a hardness that you can't dig into with a 62 rockwell C file.

[Alan Roehrich]

Where on the cam did they perform the Rockwell test?

[Terry Cain]

One more question. Is it a Crane cam?

[rod]

I assume the test was on the actual lobes, more than that i was not told. the brake-in was with the single outer spring. [dual spring pressure was in the area of 150 seat. personally i would have used a lower pressure for the brake-in, because the springs had to come off any but.....]
yes roller rockers and it was a lunati [sp] solid lifter.
anyway the cam tested low on the rockwell. so Andy is really ticked off.
thanks for the help.
rod in AZ

[Reed Granrt]

All flat tappet, whether hydraulic or mechanical, are case hardened. Most are nitrided by one of several methods. This nitriding is only a coverage of the camshaft. It means it can only go so deep. Once a cam starts to wear and it goes thru the nitriding, or case hardening, we then get down to virgin metal. You should be able to check the camshaft at any place, except the one that failed, on the camshaft. Checking the cam at the failed lobe is of no good at all. If the lobe is lost, you have broken thru the hardening. You are much more accurate to check a ground surface. You probably would be better to read it in Rockwell C as more people understand that scale. The nitriding procedure has to be formulized to treat the exact kind of metal you have. Steel is treated differently that cast iron. If you are reading in the 30's on a good lobe, then most likely it was not nitrided or something was wrong in the process (screwed up). I was involved in gas nitriding 100's of thousands of parts for several years. You can solution nitride or gas nitride. Advantages and disadvantages to both. Speed is one of them.
my 1.5 cents worth. Oops wait, that has gone down to .5 cents(inflation)
reed

[Marine One]

Should the cam and lifter be the same? No - never. If you want to see two metals eat each other up (cam to lifter, bearing to race, etc) just make them the same hardness. One of the two has to be a little softer.

Keep in mind that abrasive wear is the fastest growing type of wear you will see. Ever have a bearing go out in a rear end? It starts with a low growl, then just keeps getting louder and louder until it sounds like someone is running a bench grinder. That is a good example of abrasive wear. Once it starts, there is no reversing it. It just keeps getting worse and worse.

[Jeff Lee]

MACH Development in Maricopa, AZ has a coating they apply to the cam & lifters that requires no cam / lifter break-in and you can start the engine first time with upwards of 520# spring pressure and let it idle if you want. I believe it's $150 total but contact them and find out for yourself.