Norton Service Release Database N3/13

SERVICE RELEASE N3/13

NATURE OF RELEASE: Camshaft interchangeability (read in conjunction with Servive Release N77) MODELS AFFECTED: 1970 and 1971 Commando (all models) PARTS AFFECTED: Camshaft/Crankcase/Cylinder heads and valves DISTRIBUTION: Worldwide (for general distribution) EXPLANATION: Following the introduction of new crankcases with modified breathing, together with the introduction of the Combat "SS" type camshaft, there are now several possible combinations of crankcases and camshafts. In addition, where it is desired to fit the high performance "SS" type camshaft to a pre-1972 engine there are problems with cam lobe clearance at the crankcase oil filling shroud. In addition problems can arise due to valve head diameter, valve stem and spring length discrepancies particularly where an early "non-Combat" cylinder head is fitted. It is also essential to fit tappet locating plates 063092 to accommodate the increased lift on both "SS" and "SSS" camshafts. The part numbers and applications of the various components are tabled below:- Use scrolled journal camshafts prior to Engine Number 204048 with plain bushes NMT2036 & NMT2037 Use plain or scrolled journal camshafts subsequent to Engine Number 204049 with scrolled bushes 062600. NOTE: Scrolled condition camshafts only will be supplied against orders for all above camshafts. Surface Treatment. 3 Conversion from standard cams to Combat condition requires the following:- a) Cylinder head 063327 to provide 10:1 compression ratio b) . Solid skirt Combat pistons (063348 LH, 063349 RH, Std. )-see Service Release N. 2/4 for oversizes c) Combat valves-inlet 063283, exhaust 063282 d) Standard valve springs NM22838 outer, NM22839 inner using spring seat and spacers to provide 0.050 in. (1.27mm) clearance at fill lift. e) Combat tappet locating plates 063092. + Conversion to "SSS" specification -as Combat from standard -no further action required for Combat .   ACTION: 3 Conversion from standard cams to Combat condition requires the following:- a) Cylinder head 063327 to provide 10:1 compression ratio b). Solid skirt Combat pistons (063348 LH, 063349 RH, Std. )-see Service Release N2/04 for oversizes c) Combat valves-inlet 063283, exhaust 063282 d) Standard valve springs NM22838 outer, NM22839 inner using spring seat and spacers to provide 0.050 in. (1. 27mm) clearance at fill lift. e) Combat tappet locating plates 063092. + Conversion to "SSS" specification -as Combat from standard -no further action required for Combat May 1972 Norton Villier Canada Limited