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TR2/3/3A The timing mark on the crank pulley....

There is only one mark, which should be TDC (unless someone has assembled the pulley wrong).
Dh9BtZw.jpg


The advance curve starts really low on these engines, making it difficult to accurately set initial timing with a light. My suggestion is to start at about 3/16" from the TDC mark (which is about the 4 BTDC called for in the book), and then advance it a degree or two at a time until you can just force the engine to ping a little, by using heavy throttle at low rpm (30 mph in 4th gear) with the engine thoroughly warmed. Then I like to back off by about 2 degrees (half of a hash mark on the distributor vernier), just to be safe.
 
There is only one mark, which should be TDC (unless someone has assembled the pulley wrong).
Dh9BtZw.jpg


The advance curve starts really low on these engines, making it difficult to accurately set initial timing with a light. My suggestion is to start at about 3/16" from the TDC mark (which is about the 4 BTDC called for in the book), and then advance it a degree or two at a time until you can just force the engine to ping a little, by using heavy throttle at low rpm (30 mph in 4th gear) with the engine thoroughly warmed. Then I like to back off by about 2 degrees (half of a hash mark on the distributor vernier), just to be safe.
Just speculating: Would a motor with a mild street cam and headers take 8 degrees advance?
 
It's possible. The initial recommended setting is a starting point. The final determination for spark is during driving tests. With the engine fully warm, tranny in 3rd or 4th gear, and about 2000RPM, floor it and see if you get detonation (pinking according to the manual). If you don't, you can use the Vernier on the dizzy to advance a degree or so...then try the test again. Once you do get the detonation, back the timing off a degree or 2 and you have the optimum timing for your engine.

Oh, in the picture above, Advanced would be with the crank circle to the left of the indicator. Retarded would be to the right.
 
Even if you had a bunch of marks on the damper like a TR6 indicating theoretical degrees that #1 piston is from Top Dead Center, you'll see that the word "nominal" is used in this Haynes manual
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IGNITION TIMING per HAYNES 003.jpg
 
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