[Healeys] Flywheel orientation

[Elton Schulz]

Fellow Listers,
I am about to reinstall the flywheel on my BJ7. The
  instructions in the shop manual are confusing to me. It states "Place 
the flywheel --- so that the timing mark "1" is at TDC when the first 
throw of the crankshaft is at TDC."
Could someone explain to me what that means. I found the "1" mark on the 
flywheel but am puzzled as to where the referred TDC position is. Is it 
referring to the 12 o'clock position? And what is the meaning of the 
"first throw of the crankshaft at TDC?
Thanks for your help,
Elton