Cam timing?

[flyinglizard]

I lost a link for the optimal cam timing.
   I know that I read  a short performance upgrade page here. Where is it??
 TIA.
  On another note. How much better fuel economy will a 3.9 diff do over my current 4.1 ?
      Fl. has some fast traffic and I feel bad cruising at 4200rpm.
 TIA. Mike Ogren , 91 IS