VALVE ADJUSTING ON THE 4 CYLINDER ENGINE
It is possible to hold the tappets so that they can be adjusted by drilling a 1/8” hole in each tappet through the block after they are lined up on top dead center of the compression stroke for each cylinder. Try to have the tappet turned so that the drill enters the void in the tappet instead of the metal of the tappet. Drill the hole as close to the center of the tappet as possible. A smaller drill bit than 1/8” inch can be inserted into the hole to hold the tappet so the adjusters can be turned. Recheck the clearance after the drill bit has been removed. The piston should be on TDC of the cylinder you are adjusting. If you will start with the #1 cylinder and make a mark on the front pulley with a whiteout pen etc and then a reference point to it on the block somewhere then make another mark on the pulley 180 degrees across. After you have adjusted the first #1 cylinder to get the next cylinder in the firing order to TDC turn the engine untill the next mark on the pulley is at the reference point mark and adjust the second cylinder in the firing order. Do this turning the engine 180 degrees each time till the next pulley mark is at the reference mark until all four cylinders have been adjusted or checked. This procedure keeps you from having to find the compression stroke on all the rest of the cylinders.
The original mushroom shaped valves on the early Ns were not adjustable with hand tools. They had to be ground to fit.