Top Dead Center is when the #1 cylinder piston at the top of its stroke
just after the compression stroke. This is when the #1 spark plug will
fire. This location is used for setting the timing gears or chain and
for locating (clocking) the distributor. Be careful, you can be off by
one full rev of the crankshaft because top dead center occurs every
other revolution. The #1 piston is also at the top of its stroke just
after expelling the exhaust gas and just before air/gas intake for the
next spark plug firing. So, if the #1 piston is at the top of its stroke
and the exhaust valve just closed and the intake valve is just opening,
you are 180 degrees out of phase. Rotate the crankshaft 1 full
revolution. If the #1 piston is at the top of its stroke and the exhaust
and intake valves have not closed/opened, you are at top dead center
(TDC) and the distributor will/should be pointing at the #1 spark plug
wire.
To bring the motor to top dead center, disconnect the spark plug wire
from the ignition coil, remove all the spark plugs and remove the valve
cover from the #1 cylinder valves. Jog the starter (or rotate the
crankshaft by hand) until the #1 exhaust valve is almost closed and the
#1 intake valve just starts to open. Then rotate the crankshaft 1 full
revolution. When you are close, you can measure the height of the #1
piston with a screw driver in the #1 spark plug hole. Be careful not to
let the screw driver bind against the piston or the head. Rotate the
crankshaft back an forth slightly until you have located the highest
point for the #1 piston. This is top dead center.
Ensure that the crankshaft key is aligned with the timing mark on the engine block......then slide the sprocket on the end of the crankshaft, as shownInstall the inner timing chain so that the dark blue chain link is aligned with the matchmark on the idler sprocket......and the yellow link is aligned with the matchmark on the crankshaft sprocket.
Also, keep in mind your correct firing order...
Hope helps.