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<x-charset iso-8859-1>The British Type 3 analyses give details of the cam and follower metallurgy and the microstructure. >From the 1961 Notch, the details are:- The steel alloy has 2.89% graphitic carbon out of a total carbon content of 3.62%, with 2.5% Silicon, 0.93% Manganese, 0.86% Chromium, 0.52% Molybdenum and 0.2% or less of Ni, Va, Ti, Cu, and Mg. The tip of the cams has a hardness in V.p.n. of 590 at 10kg load and 262 on the bearing surface. The camshaft was made of heat-treatable alloy cast-iron which had been surface hardened on the cams by flame or induction hardening (they couldn't tell which). The hardened zone is about 2mm thick around the shaft and about 7mm maximum at the cam lobe, as shown by the Nital etch picture. How the hardness varied with depth I can't say; the picture doesn't reveal any obvious difference, but it must vary as the bearing surface is not as hard as the cam. The 1969 TLE Fastback covered the followers:- This alloy had a bit less graphite, a lot less Va, and more Cu, Mg, Ni and P. It had been induction hardened to a depth of 0.032". The average V.p.n of the surface measured 660 with a 5kg load. I don't know exactly what this means, but I guess some of you technical boffins recognise a Vickers Pyramid Numeral when you see one. Any comments from the metallurgists on the list? Dave. UK VW Type 3 & 4 Club http://www.hallvw.clara.co.uk/ ------ ------------------------------------------------------------------- Unsubscribe? mailto:type3-request@vwtype3.org, Subject: unsubscribe </x-charset>