This was a great reply by Ed Mayo on the PCA.org Technical Q&A Section. Note to Ed and/or moderator, please let me know if it should be deleted due to any copyright issues (I did not see any on the E-mail I received)...

Classification: Engine
Subject: step by step valve adjustment instructions
Model: 911T
Year: 1973
Total Mileage: 86000
Car Use: General

Question:
I would like to attempt a valve adjustment during my next oil change do you have any good step by step instructions ? The manual that I have (Haynes) is not very clear what takes place after finishing the first cylinder. I have the proper feeler gauge, and gaskets, etc. I would just like a little more info.

Answer:
The first answer is that you adjust the valves in the same order as the engine firing order, that is 162435. If you don't already, you need to know the location of the cylinders, that is looking from the rear of the car the rearmost cylinder on the left (drivers side) is #1, going forward is #2 then #3. The right side is 4-5-6, #4 being at the rear. The decals on the engine lid latch panel will show this (if they're still there). This can also be found in the owner's manual, not to mention your Haynes manual. By the time you're done you will have rotated the crankshaft two complete revolutions. You will need to look carefully at the crank pulley so that you can find the marks you'll need that indicate cylinder TDC (top dead center). For as much as you'll be rotating this engine you'll find it easier to remove all the spark plugs first, but it can be done with them in if you wish.

Rotate the engine either by using the wrench on the fan pulley (you'll need to always push against the right side of the fan belt to get enough tension) or use a long series 19mm box end wrench on the crank pulley nut. You'll need a good light at this point to see the crank pulley marks, turn crank until you get the TDC mark lined up with the notch in the blower housing. There are two marks, one at TDC and one a ¼" away which is 5 degrees after TDC. There are also two marks at 30 and 35 degrees advance which look the same. Be sure you don't have them! You may need to use a light and mirror to see the marks. They are all stamped with appropriate numbers, Z1 is the mark you want, put a dab of white or yellow paint on it.

Now rotating the crank clockwise the next mark you see (in about an inch) is marked FE, you don't need that, keep going, the next mark will not be labled, and it should be about 120 degrees from the TDC mark, paint mark it.

Rotate engine 120 degrees more, find mark and paint it.

Rotate 120 degrees again and you should be back at Z1 (you'll have passed 30 and 35 degrees marks).

Now remove distributor cap and find small mark indicating #1 cylinder firing position for rotor, rotate engine so that Z1 pulley mark aligns with notch, and rotor TIP is aligned with mark on distributor.

Now you adjust valves on #1 cylinder.

Next rotate engine so the next painted mark aligns with blower notch, that will be cylinder #6 (next in firing order).

Next 120 degrees will be for #2, then back to TDC which will be #4, and so on.

Now all you have to do is develop that "feel" for the adjustment. You will break several blades until you develop this. You have to "walk" the gauge in between the valve and rocker, and it must be perfectly flat. Most people tend to make the adjustment too loose, .004" means you could not get a .005" blade in there. Good luck.

Ed Mayo - PCA WebSite - 7/27/2007