Lamborghini Miura manual indicating bigger intake valves in English size (but correct size in metric). The intake and exhaust valves in all 4 liter Lamborghini V12 remained the same throughout all models. This intake size misprint carried forward into Espada 400GT and Countach LP 400/LP 400S owners manuals as well. In 1970, Lamborghini development driver Bob Wallace created a test mule that would conform to the FIA's Appendix J racing regulations. The car was appropriately named the Miura Jota (the pronunciation of the letter 'J' in Spanish). Wallace made extensive modifications to the standard Miura chassis and engine. Weight reductions included replacing
V12 engine the advantages of lower centers of gravity and improved pilot visibility for single-engined designs. Only the pre-war origin BMW VI V12 of Germany was an "upright" engine. The United States had the experimental Continental IV-1430 inverted V12 engine under development, with a higher power-to-weight ratio than any of the initial versions of the German WW II inverted V12s, but was never developed to production status, with only 23 examples of the Continental inverted V12 ever being built. The only American-design inverted V12 engine of any type to see even limited service in World War II was the air-cooled Ranger V-770,