Mainshaft Shims to fit OHV and SV Engines (i.e. 16H/Big 4/Mod 18/ES2/Mod 19 etc. Set of 6 shims - 2 each of the following 3 sizes: 0.030”/0.018”/0.012".
Fitting Notes: Norton's did not list mainshaft shims in their 1948 or 1955 Spare Parts Catalogs (the two most well known OHV/SV spare parts lists) - perhaps because shimming was not considered as important on the SV/OHV engines as it was on the SOHC engine (which required shimming to ensure correct mesh of the bevel gears). But never the less . . . it is still good practice to shim the mainshafts to ensure best position of the conrod - which should ideally be centralised to the crankcase mating faces, when conrod is positioned in most central position on the big end journal.
Therefore these shims are essential for placing on the timing side mainshaft, between flywheels and timing side main bearing, to help ensure the flywheels and conrod are best centralised to the barrel. In addition, if you are using a roller bearing on the innermost drive bearing - and have clearance on the mainshaft - these shims can be used to stop the inner roller bearing 'floating' excessively on the mainshaft. When racing OHV engines in the 1980's I always undertook this task.
Note: although I do not show it as a seperate item - individual shims can be purchased at a cost of £2.80 if required. Just add a note in the comment section when placing order and specify which additional size required
By the way - the pictures here are of a mid 1950's crankshaft - timing side first and drive side in the second photograph (and actually this is a rarer 600cc Model 19 crankshaft with 8" conrod), but these shims should fit all SV and OHV models from 1930's to 1950's. Also, unlike the SOHC engine, the mainshafts on both sides were the same diameter, hence why this set includes 2 of each size shim.