The 10 inch ID 110 tooth ring gear is the most common size for the Formula Ford 1600 engine. This high-strength ring gear will work with Tilton and Lucas starters and is less prone to tooth wear than the standard ring gear. This makes it ideal for use with Lucas (inertia) starters, which spin prior to engaging. When used with the Lucas starter, the ring gear should be installed with the tooth chamfer facing the transmission. Tilton starters do not require the chamfer and will work with the ring gear installed in either direction.
Note: Some later cars use a 10.12" ID 110 Tooth Ring Gear (Part No. 173-03), and some later British formula cars use a 132 tooth ring gear. Be sure to check your car before you order.