Ground To Earth ? ? ?

[SCHOONER]

HI EVERYONE

PROBLEM: I NEED TO FIND A LOCATION TO GROUND THE FIREWALL.
JUST WHERE AND HOW THE HECK DO I DO THAT ?

YES, I CAN GET A BATTERY CALBE OR SOMETHING SUITABLE TO GROUND WITH. YES, I CAN DRILL AND BURNISH THE AREA WHERE THE GROUND FROM THE ENGINE TO THE FIREWALL GOES.

BUT JUST WHERE DO I PLUG INTO THE ENGINE OR FRAME ?

THE FIREWALL IS EASY; JUST BURNISH AND DRILL AND PLACE A MEDIUM SIZE SHEEP METAL SCREW AND I'M IN BUSSINESS.

NEED ALL YOU SUGGESTIONS PLEASE.
GOD BLESS ALL OF YOU GUYS/GAL

SCHOONER