My brother owns a 76 L48 and he keeps burning out coils. New coil run fine for a while but they get hot after running a while and finally start missing and then just quit. Any ideas would be helpful

Some Coils call for a ballast resistor some don't,
If you are direct wiring a resistor coil to a system that the resistor has been removed it will cause just the problem you describe.
Best of Luck,
Cheers, T.