[dalewrc30]

[quote=desmo11;498680]Ah. AISI9310 / AMS6265 (AMS from memory).

I'm afraid you're very, very optimistic on the hardness values. It's probably more like HRC ~60 (max),

As for EN40B or nitrided cams I have to disagree with you there. Commonly cams are nitrided to .004-.008" depth and work just peachy in many applications (including F1). They are flat out as tough as nails. The advantage to nitriding is less deformation. Your core hardness is HRC mid to low 40's on either carburized or nitrided so no difference there. Just get rid of the white layer from nitriding.

Hi Desmo,

the hardness figure is from the catalogue supplied by my steel merchant.Up to 64,so probably in the low 60s.
Dave does cams for a guy who supplies Triumph twin cams to the US.They are nitrided,however he had to take a lick off a set recently ,less than .002",and it pretty much went through the hardening and they could be filed!
He was told by the heat treatment company that although the hardening does penetrate to the kind of depth you have indicated,it drops off very quickly from the surface,so much so that the hardness tester they use,requires a different(much gentler) application to measure hardness.

As for core strength,as I understand it,a metal treated at 880*C then quenched will retain pretty much all of its Toughness whereas a metal nitrided at 550*C will suffer a substantial drop off.

Again,I dont hold myself to be an expert on these things,this is just what I've been told by the guys I trust.

I'd have no problem nitriding them myself,but the last thing I want is guys buying these and suffering a failure some time or ruining a set of cams because another part failed and they weren't able to repair them.With a .040 case depth,its probably going to have full hardness for at least .030".

If anyone wants to go down the nitriding route,theres going to be a saving.After having a closer look into this,the cost of case hardened sets will be more like US$1500 delivered.
Nitrided sets will be US$1200 delivered.

Dale