Took the driver side valve cover off. Photos are taken with
- pass side index holes horizontal
- driver side cam is 1/2 tooth before TDC
- crank in exact TDC

I was told there is a timing mark visible on the cam. Where do I need to look for it?

 

I re-did the timing (no cam marks found to allow max precision) with the cam lock tool. This time, locked crank again at perfect TDC, but loosened only the cam nut where the index plate was a tiny bit of perfect horizontal (insert the cam lock pins in that sprocket to get a longer 'lever' and find (through slight up/down movement the high/low point (there is some play in the pins/holes). Loosened the bolt and pupped the sprocket. Then finger tight only and pushing/pulling timing belt in various sections (to allow tension to even out).

Win cam lock pins feeling 'in the middle' of their play, carefully tightening the cam bolt.

Engine runs nice.
I lowered the timing belt tension even more; 2 finger 90 degree twisting (to be performed on the longer run between water pump pulley and passenger side cam sprocket) is now fully achieved.

Side note: Still wondering if a more accurate (rather than guessing) set point is possible. Using the torque to tension (I think I read in Bentley that the 30V heads are tensioned this way?) may not be possible by the design of the tensioner locking bolt (it seems to be designed to apply locking for early with increasing tightening, so torque readings (for rotating the tensioner) could be heavily influenced by the locking bolt.

After several idling warm ups I took the car to the shop for an accurate compression test.

Prior to the timing belt job (same place, same instrument, same procedure), with the 'as bought' settings and a notably sloppy timing belt (turns out it was quite new), we recorded:


Front to back
Passenger
160
125
110

Front to back Driver
150
125
110

After the timing (and re-timing):

Front to back
Passenger side:
148
160
160

Driver side:
155
155
152

==> The numbers are good and pretty consistent (IMO). No signs of bent valves, excessive cylinder/piston wear or leaky valves/head gasket

Most surprising: the front 4 cyl had substantially lower compression prior to the timing (30 psi lower than the 2 rear cyl). Now they are 'in line'. Could this be attributed to the sloppy (low tension) timing belt and/or to 'not so great' timing?

Either way: Engine sounds and runs good. Since I destroyed the new belt and replacement was not yet on hand, I installed the (very new looking, no cranks, sharp teeth; ditto the water pump: virtually new looking. Could be that timing belt job was recently done by previous owner) old timing belt.

Now big question is: Go back and change the belt (getting lots of practice in that)?