On 1/9/16 2:31 PM, Michael Porter wrote: > I think all the TR4s were listed as 2138cc. IIRC, the factory manuals > listed TR4s as 100 bhp, while the TR4As were listed as 104 bhp, which > was attributed to a minor cam profile tweak and the change in exhaust > manifolding. The 4A heads had slightly different porting which improved the flow a little as well. TeriAnn