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Hi does anyone know the recommended torque for the bolts that hold the sprockets for the top timing chain to the camshaft?.
About every other torque figure is quoted but I've never seen one for this. As it's a 5/16 bolt I'd reckon about 20nm (15ft/1b). (I've got the later 4 bolt sprocket and camshafts for XJ6 S3, together with a big valve/ported head)

Hi

If its an Inch/Imperial size screw then it should have equi-spaced radial markings on the top. 3 marks is grade 5 (or P), 6 marks is grade 8 (or S) and 9 marks (dots) is grade L9 (T rated). Nominal torque figures are 8.2, 15.7 and 17 lbf ft respectively for dry assembly of unplated screws. These figures should take you to around 90% of yield strength.

Reduce these figures by around 20% if assembling lubricated or if plated (unlikely inside the engine). Reduce by a further 10% if plated and lubricated.

Hope this helps.

Regards