That's one Hard Fox! A Stone Fox!
Stone Fox by John Reynolds Gardiner, 1980.
Immediate tension and simple language make a fast, easy read.
The plot always moves forward but generally without much elegance or plausibility. Many questions remained unanswered, the largest being, how could a ten-year-old care for an ailing grandfather on his own? Changing sheets? Bathing him? Bathroom duties? Perhaps because of the overly simplified language I had difficulty making an emotional connection with the protagonist. And the race, although very intense, seemed like a deus ex machina.
For the male (or female) sports-loving emergent reader, however, I could see this book being top pick.