Timing disc
for precise camshaft timing
Valve timing instructions
Owing to the variation in centre distances between crankshaft and camshaft, particularly if the cylinder head has been skimmed, and the manufacturing process of high performance camshafts, it is not always possible to use the standard marks, and vatve timing should be checked in the following manner.
Determine true T.D.C. position of the engine by rocking the crankshaft whilst No. 1 piston is at the top of the bore. There will be approximately a 10 degree dwell period and true T.D.C. will be in the centre of the dwell period. Having obtained true T.O.C. fit Timing Disc to crankshaft and set to zero. Now rotate crankshaft clockwise to the full lift position specified for the particular camshaft being fitted. It is at this position
that No. 1 inlet valve should be fully open. This can be checked by fitting a dial indicator gauge on No. 1 inlet valve spring retaining cap and rotating camshaft until valve is fully open. Once again approximately a 10 degree well period will be shown and true full lift will occur in the centre of this dwell period.