29.3mm exhaust valve in EN21 steel. 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 3.44" & 3.56") three different cotters, (wide, narrow, and three-groove) and many different head diameters. These 29.3mm valves are really a great quality valve for road use and used in Minispares gas flowed road heads.
These exhaust valves are triple collet groove type as used on all A plus heads
12G1316 (Smog-Type) and all variations of the 12G940 and the latest CAM head castings, they all use the the 3.56" long valves.