There are a number of different methods of cam timing. We at Kent Cams use either the 'Lift at Top Dead Centre' method, or the 'Full Lift Position method'
Full Lift Position method:
For many years the most commonly used method has involved establishing top dead center (TDC) as a datum (zero degrees) and positioning your camshaft with its inlet valve at maximum lift at a given position relative to this datum. For example take our Ford x/flow camshaft number 234 which has a quoted figure of inlet timing @ full lift = 103 degrees. This means that the inlet valve should be set to be fully open at 103 degrees after top dead center. Therefore using a protractor or timing disc you can establish 103 degrees after TDC and it is at this point that your inlet valve should be fully open. Minor adjustments from the standard timing point can be made with the aid of adjustable timing kits or an offset dowel.
Lift at Top Dead Centre:
In recent years with the proliferation of multi valve/multi cam engines this method can be a labourious hit and miss affair. This is solved by setting all of your camshaft timing at a specified lift at the previously used datum of TDC. This Method has been in use by Kent Cams and many top engine builders for many years. This method is relative simple and has the benefit of setting individual cams at the same position without resorting to excessive crankshaft rotation. For example the Ford x/flow camshaft 234 has a quoted 'TDC' lift of 2.84mm. This means that when the piston is at overlap top dead centre (not the firing TDC) the cam should be set so that the inlet valve has 2.84mm of lift.