31. Helmets also have a spring-loaded exhaust valve which allows excess air to leave the helmet. 32. These actuated the overhead steel intake and exhaust valves . 33. Each exhaust valve on the J37A4 corresponds to one primary and one secondary exhaust rocker arm. 34. Also unusual was the adoption of only one hairspring valve spring to close the exhaust valve . 35. A DOHC design permits a wider angle between intake and exhaust valves than do SOHC engines. 36. Exhaust valves were sodium filled for cooler operation.37. Valve overlap is a secondary means to cool exhaust valves with intake air during valve overlap. 38. At 4 the exhaust valve opens, and the pressure falls abruptly to atmospheric ( approximately ). 39. Cylinder deactivation is achieved by keeping the intake and exhaust valves closed for a particular cylinder. 40. There are three intake and two exhaust valves .
