should be getting a reasonable 9-10L / 100kms
My T18 gets about 11L - 100kms and I have a 38 38 weber carb, extractors, 2" exhaust, with a very tall ratio diff (4.8) and thats not trying to get any kind of fuel econamy just driving and having fun like it was made to do. But before all the mods it was getting 9L around town and 7 on the highway that was after a good tune up new plugs, adjusted points, ect.