The Ferguson TE-20 used a version of the Standard-Triumph wet liner 4 cylinder engine from 47 to 56. Much higher performance versions were used in the Triumph TR-2,3,4 sports cars. A TR-4A cylinder head, 87mm liners, dual carbs etc... would bolt on.
This is where the often heard comment about Triumphs having "tractor engines" came from. Truth be told, Ferguson used a beefy automotive engine in their tractors.