Engine No. Model 18

W usually (maybe always) denotes WD 16H or Big Four. Side valve. Same casting as the Model 18 but differently machined.

Previously roger_baudains wrote:

Anyone know if w87961 relates to an ohv 18 engine or can confirm which engine it relates to

Cheers

W designates a war department 16H. The war department Big 4's used an "S" before the engine/frame number.

regards