Overview Reviews Product Description Extended Starter Nut Briggs 5hp Flathead. Thread 5/8 - 18 and 2.625" overall length. Uses 3/4" socket wrench. Product Videos Custom Field Product Reviews Write a Review Write a Review × 6434 Starter Nut 5/8-18 Briggs 5HP Flathead Extended Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Email * Review Subject * Comments *