In a small bowl, whisk together the bourbon, vegetable oil, vinegar, mustard, salt and pepper.
Place the beef in a large lock-top plastic bag and pour in the bourbon mixture.
Press out the air and seal bag tightly.
Refrigerate for at least 1 day or up to 3 days, turning the bag occasionally.
Prepare a fire for indirect-heat cooking in a covered grill.
Remove the meat from the marinade and pat it dry with paper towels.
Boil the remaining marinade and reserve.
Place meat on the center of the grill rack, cover and open the vents halfway.
Cook, turning 3 or 4 times, and brushing with reserved marinade, until the roast is well browned and a thermometer inserted into the thickest part registers 130 degrees F for medium-rare or 140 degrees F for medium, 45-60 minutes.
Transfer the chuck roast to a cutting board. Cover loosely with aluminum foil and let rest for 10 minutes.
To serve, carve into slices across the grain and arrange on warmed individual plates.
