1.401" dia x 3.52" long intake valves. Our race valves are produced in EN214N steel, stellite tipped and use the later narrow collet groove and current valve head shapes. As it is possible, even common, to swap one head for another on 1275 engines, it is quite easy to become confused, or worse yet, confuse the parts-guy when it is time to order new valves! Be aware that if the head has been worked on previously, it may have oversize valves; it may have undersize if seats have been installed. Unless you are 100% sure what is in your cylinder head, it is a good idea to remove a valve for accurate measurement. There are two lengths used (nominally 3.52" & 3.57") three different keepers, (wide, narrow, and three-groove) and many different head diameters!
Early Cooper S valves
If your 970, 1071, or early 275 Cooper S still has the original AEG163 head casting, you must use short, 3.52" valves.