This will be the second time I've written this. The first potsing crashed, so if there is a double post, mea culpa.

Background: My 75 SR5 blew a headgasket. Had the head machined for $70. The head, cam, rocker arm assembly was re-installed, and now is the valve adjustment phase.
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I'm a visual learner, and the written details might be over elaborate. This is done for others to add their comments, perspectives, and suggestions.

1) First I set the the engine to Top Dead Center Compression (TDCC). This was done by moving the CRANK pulley to where the timing mark/diit on CRANK PULLEY is aligned directly below the ZERO ("0") on the timing guide.

2) Confirmation of TDCC was done by the location of the timing mark/dot on the CAM SPROCKET GEAR. The Timing mark/Dot is pointed upward at the 12 o'clock position. Both he Crank pulley and the Cam Sprocket gear markers are pointed upward at 12 O'clock.

3) At TDCC, two valves are open to INTAKE and two valves are open to EXHAUST.
The two for INTAKE are the first two from the front on the passenger side; the two at EXHAUST are the number one and number three from the front on the driver side.

( See attached pic from HanyesManual. The letter "F" may have been omitted from "Front" ).

Before I started the adjustments, the current clearances were checked with a Feeler Gauge. ( The clearance for Intake : 0.008; the clearance for Exhaust: 0.012. )

The wasn't ANY clearance PERIOD! I couldn't get a Feeler gauge between the adjustment screw and the Valve stem on seven of the eight valves! Only one was set per standards. I wonder if this lack of proper spacing/tolerances contributed to the engine over heating that resulted in the headgasket failure....

4) I loosened the valve tightening/securing nut (12mm) on the the first Intake valve and also loosened the adjusting screw. I placed in a 0.008 Feller Gauge, and adjusted until a slight-but-firm resistance tug on the Feeler Gauge before tightening the securing nut. I did the same for the remaining Intake Valve and then again with the Exhaust Valves at 0.012.

5) After those four valves were adjusted per specification, the CRANK pulley was rotated one full turn with the Timing Mark once again set in line below the Zero (0).This would be Top Dead Center Exhaust ( TDCE).

This TDCE was confirmed be viewing the timing mark/dot on the CAM Gear Sprocket. The timing dot is now 180 degree opposite at the 6 O'clock position.

 

20R - Rocker Arm Valves Adjustment - Pics _ Part Two

6) With the engine now set at TDCE, the the next set of valves were adjusted: Intake to 0.008 and Exhaust to 0.012 - the same specification as were used in the previous set.

( See attached picture from the Haynes Manual - TDCE )

( Note: The attached pictures for this set are out of sequence. The pictures in this set were taken for the previous adjustment of TDCC. But the the adjustment on the tightening nut (12mm), adjustment screw, feeler gauge, and valve stem are the same. The pictures are for visual reference help for the Feeler Gauge, adjusting screw, tightening nut..... )

I checked and double checked the valve clearances with the Feeler Gauge on both sets of adjustments. Though I had to go back and do a re-adjustment a couple of times when the tightening bolt moved the adjusting screw upon tightening, overall everything was easy to do!

7) I reset the engine to TDCC for the next step: Re-Installing the Distributor.

( The final two pictures is confirmation of the Valve Clearance specification of Intake 0.008 and Exhaust of 0.012, and the crank pulley re-set to TDCC )

Your thoughts, experiences, and perspectives requested...