3Pb(NO3)2 + 2AlCl3 = 3PbCl2 + 2Al(NO3)3 Is the balanced equation.
If there are 8 moles of ALCl3 used instead of 2, the number of moles need of the first reactant needed will be 6 moles.
The new balanced equation is: 6Pb(NO3)2 + 8AlCl3 = 6PbCl2 + 8Al(NO3)3