On a 4 cylinder engine, simply use the “rule of 9”
You don't need to find T.D.C. but, just view the valves when fully opened as you rotate the crankshaft.
Numbering the valves from the front of the engine from 1 to 8:
With number 8 fully open, adjust the gap on number 1
7 open, adjust 2
6 open adjust 3…etc
. i.e. always add up to 9
Of course, to save lots of engine turning, you don't need to do them in strict numerical order…as you rotate, simply spot the valve that is fully open and then adjust the one in a position that adds up to 9.
