High quality Gates 160 degrees Fahrenheit/71 degrees Celsius thermostat to suit all Small Block 273, 318, 340 & 360 fitted to various AP6-CM models & Big Block 361, 383, 400 & 440 engines. This is manufactured from stainless steel featuring a bleed valve & is a high flow/volume version recommended for medium-high performance engines as it increases coolant flow and improves cooling system.