Below is the distributor hold-down bolt which resides under the distributor, you can see the sun shining on it in both pictures. To change the timing:

1. First obtain a timing gun (normal or one with the advance feature)
2. Make sure the engine is warmed up and running at a normal idle level [during the whole procedure].
3. Hook the #1 cylinder up to the timing gun and the two terminals to the battery.
4. Check your current timing by aiming the timing gun near the belts on the right side of your car directly on the crankshaft pulley. There are 7 tick marks, starting from the left (closest to the windshield) 0, 5, 10, 15, 20, 25, 30 degrees. The first tick mark is technically supposed to be orange, but might be covered up from dirt.
5. There is a timing indicator (I call it an arrow) which indicates where your timing is when the light from the gun is flashing on it. If you see the arrow on the middle mark (4 from the left when standing at the right front tire), then your timing is right at 15 degrees.

6. Remove the "ECCS" cover.

7. Obtain a 9 mm socket with an extension and loosen the below distributor hold-down bolt.

            a.  Be careful to keep the wires away from the accessory belts or cooling fans

            b.   Do not take the screw out, only loosen it a little.

8. Once the screw is loosened, put your hand on the distributor and slightly turn it to the right (advancing). Have the nut on the distributor snug enough where it stays in place for fine tuning.
9. Next, check your timing with the gun. I recommend going with 20 degrees, which is the 3^rd tick mark from the right (5^th tick mark from the left). 18 is also a good number and you can adjust accordingly for it.
10. Tighten the distributor hold-down bolt
11. Re-check the timing to ensure the distributor stayed in place while you tightened it.
12. Disconnect the timing gun
13. Put the distributor cover back on.

Take the car for a test drive and make sure no knocking or pinging occurs. If it does, retard the timing slightly. 

Note 1 if you have an advance able timing gun, you can use it’s feature, which allows you to dial the timing in on the gun itself and base everything on the left-most tick mark. With this setup, you really don't need to use the advance feature and can just use the tick marks. The only advantage in my eyes with using the advance feature is that it is a little more easy to determine the left most mark than the 3^rd mark from the right (20 degrees)

Note 2 Higher octane fuel is recommended with the advanced timing setup. I alternate between 89 and 93 octane and haven’t had any problems.