"I couldn't find the sports car of my dreams, so I built it myself"

- Ferdinand Porsche

Cam Timing:

By: Cole

Crankshaft to Camshaft Relationship: 

Always rotate the crank in a clockwise direction. 
All ignition and cam timing operations will reference Z1. Z1 is the designation used for the position of the number one piston in relation to the rotation of the crankshaft. Z1 is stamped and marked on the face of the crankshaft pulley. There is also a corresponding marking (just above the crankshaft pulley) located on the bottom edge of the fan housing and directly in line with the case split where the right and left engine case halves come together. If the Z1 mark on the crank pulley is directly aligned with the case split or fan housing marking it indicates that the No.1 piston is at the very top of its stroke (TDC or Top Dead Center). This gives us an accurate and consistent reference point for timing and assembly of any engine components referenced off crankshaft rotation. 
The Z1 mark alignment with the case split indicates piston No.1 is at Top Dead Center. To complete one 4 stroke combustion cycle the crankshaft must be rotated clockwise 2 complete revolutions or a total of 720*. If you start at Z1 (Top Dead Center) and rotate the crankshaft clockwise 360* back to Z1 you have completed the first 360* of the 720* combustion cycle. Then, again, rotating clockwise from Z1 (Top Dead Center) another 360* back to Z1 (Top Dead Center) we have completed the 720* combustion cycle and the Z1 mark is aligned with the case split, for the second time, indicating piston No.1 is at Top Dead Center again.
As noted above there are two distinctly different positions in that 720* combustion cycle where the Z1 marking on the crank pulley will be directly aligned with the split in the engine case. One Z1 (TDC) position is at the end of the compression stroke or (TDC compression point) this is also the point where the ignition is timed and the distributor is installed. The second Z1 (TDC) position is 360* later at the end of the exhaust stroke/start of the intake stroke or (TDC the crossover point) this is the point where cam timing is set. 

Setting Up for Cam Timing:

Starting at No.1 cylinder (left bank first cylinder on the crank pulley end of the engine) Turn the crank clockwise to the Z1TDC compression point (both intake and exhaust valves on No.1 cylinder will be closed and the shoes of the rockers will be riding on the base circle of the cam, not on the cam lobe) this indicates you are at Z1TDC compression point.) If (either the intake or exhaust valves are open/ depressed or the shoe of either rocker is resting on the cam lob and not the base circle this indicates you are at the Z1 TDC crossover point) If you find that you are at the Z1 TDC crossover point you must rotate the crank shaft another 360* to get to the Z1 TDC compression point.
Once you are assured you are at Z1 TDC compression point adjust No.1 intake valve to .1mm /.0039 in. spec. After the valve lash is set on No.1 cylinder remove both sprocket retaining pins and adjust both cams so the dot, and/or 930 stamping marks, are pointing straight up and then reinstall the chain sprocket retaining pins. Install the Z block on the valve cover stud just above the No.1 intake valve. Insert the dial gage into the Z block and pre load the dial gage about 1 inch. and secure it with the stem resting on the outer edge of the intake valve retainer. Rotate the outer rim of the dial indicator face to zero.

Recheck everything: 

Crankshaft set at Z1TDC (compression point), make sure sprockets, chains, chain ramps, and idlers are installed correctly. Chain tensioners removed, sprocket locking pins inserted, cam dot/930 stamp pointing up, cam washer, bolts and/or nuts installed and snugged, No.1 valve lash adjusted to .1mm /.0039 in. Z block and dial indicator positioned, secured, preloaded, and dial set to zero. Now, using vice grips or hand clamp, securely clamp idler arm to the case to apply firm tension on the chains. Write down your particular cam spec range, do it in both millimeters and inches and keep it in your work area for quick reference.

Just Do It:

With your recheck done and your starting point at the, Z1 TDC (compression point), slowly rotate the crankshaft 360* clockwise to Z1 TDC (crossover point), Do not overshoot the Z1 alignment as you reach Z1if you overshoot, turn the crankshaft another 360* clockwise and start over. NEVER TURN THE CRANKSHAFT BACK COUNTERWISE TO Z1. Once you are at Z1 TDC (crossover point) look at the dial indicator reading, ideally you want to see a reading in the middle of your spec range. If you are not in that range you need to remove the snugged cam nut/ bolt and washer and pull the sprocket locking pin and using a 17mm open end wrench, adjust the camshaft to the correct setting and reinstall the sprocket locking pin, reassemble the washer and snug the cam nut/bolt. Now rotate the crankshaft 2 complete revolutions, 720*, and recheck your setting. Your setting should repeat as long as you had the cam nut/ bolt snugged enough to eliminate any creep. If you setting is not repeating, tighten the cam bolt/nut more and then rotate another 2 complete revolutions, 720*, and recheck your setting again. Once you have repeatability, hold the cam snout and tighten the cam nut/bolt tightly but do not torque yet, after you tighten the nut rotate 720* to make sure you didn’t lose your setting. If you have maintained your setting after tightening put a breaker bar on the crankshaft nut and rotate the crankshaft until you can firmly wedge the breaker bar against the engine somewhere and then torque to 165nm or 110 ft./lb. Unfortunately it may take several attempts before you get the cam to fall into spec correctly but don’t give up. As you repeat the procedure you can make adjustments when readjusting the camshaft that will offset the creep when torqueing the Cam nut/bolt. Once you have completed the left bank cam setting remove your Z block and dial indicator and repeat the procedure for the right bank.

I just finished timing the cams on my 930 and thought I'd put something together to try and help others. I read through all the threads and tryed to do this operation several times. I found that I had a tendacy to overthink everything making it harder than it really is. If you read carefully and get a good understanding of what you are trying to do and how all the setps are integrated you will make this job much easier Hope this clears things up a little.

Link to the origional Thread this artical taken from Pelican Parts Forum with permision of the author.

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