It looks like I see hairline cracks in a couple of the lobes. They look like they form a web of small cracks on one of them. The cam has been run for a long time and is a solid roller. Is this a normal place for them to crack, or am I seeing something else? I figured they would be more likely to crack in the core itself rather than across the face of the lobe. Anyone had this problem? Thanks
init2winit
I Think My Cam Is Cracked
as stated above post is correct in content.
i n other words,
the cam blank core that the grinder used to make this exact cam,..was not large enough or did npot have enough material to make the LSA or whatever, so the material was relative-ly "soft" in comparison to other lobes.
the basic "cam core" is made to allow any number of finished lobes, heat treated and such..with a certain aspect allowance to fit within certain range of finished lobe shapes,,,at least 3 or 4 so such cores exist for common engines.
a SADI core is the cheapest
then there are a number of flame hardened types
including 4140
then 8620
then 9310.
every maker of the basic core has their own spec as to the final heat treatment, to give them the desired effect.
i n other words,
the cam blank core that the grinder used to make this exact cam,..was not large enough or did npot have enough material to make the LSA or whatever, so the material was relative-ly "soft" in comparison to other lobes.
the basic "cam core" is made to allow any number of finished lobes, heat treated and such..with a certain aspect allowance to fit within certain range of finished lobe shapes,,,at least 3 or 4 so such cores exist for common engines.
a SADI core is the cheapest
then there are a number of flame hardened types
including 4140
then 8620
then 9310.
every maker of the basic core has their own spec as to the final heat treatment, to give them the desired effect.
More then liekly that was a 8620 steel core and it was not carburized deep enough.
Pressure from the roller is trying to break thru the carb layer.
For those that don't know, 8620 is a common grade of steel used for making cams. After the lobes are ground the cam goes thru a carburizing process followed by Heat Treatment. The carburizing increased the surface hardness but leaves a tough core.
The same process is performed on 8620 & 9310 rear end gear sets.
Pressure from the roller is trying to break thru the carb layer.
For those that don't know, 8620 is a common grade of steel used for making cams. After the lobes are ground the cam goes thru a carburizing process followed by Heat Treatment. The carburizing increased the surface hardness but leaves a tough core.
The same process is performed on 8620 & 9310 rear end gear sets.
I have seen this on stock ls engines 5.3-6.0l dont reuse it. Its not cracked below the surface IJS
are you referring to the horizontal lines that are in the area of where the lifter roller wheels are running....??
the indicated area is going to dig in to the surface and this is commonly due to the original cam core not being heat treated deep enough in comparison to the lobe shape that is being employed.
need a photo of the overall cam to know what the material was / is.
the indicated area is going to dig in to the surface and this is commonly due to the original cam core not being heat treated deep enough in comparison to the lobe shape that is being employed.
need a photo of the overall cam to know what the material was / is.
i have not seen that but i wouldn't trust it. i would replace it. better to spend the $300 or so now, than have it break and cause a lot more damage and cost you a lot more money. wonder what would have caused that- maybe an improper heat treating. who's the manufacturer?
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