In a large bowl, mix together chuck, pork, bread crumbs, eggs, Parmesan, garlic and red pepper flakes until thoroughly combined. Roll out meat mixture into balls 1 1/2 inches in diameter. Season meatballs all over liberally with salt and pepper.
Heat grill. Set cooking grate in place, cover grill and allow to preheat for 5 minutes. Clean and oil the grilling grate. Brush meatballs with olive oil and place on grill and cook until well browned all over and cooked through, about 8 minutes total, 2 minutes per side.
Remove meatballs to a platter and let rest for 5 minutes. Serve with marinara sauce.