Hi, I know what a Toyota Corona RT40,43,46,50,51,55 and 56 is but what is an RT41. Is it the same as a RT40 only with a 7R fitted instead of a 2R? I also have never seen a 7R engine. These early Corona's had 2R's fitted here in Australia and 3R's fitted in the USA. The sports models (1600S) had 4R's fitted withh twin SU carburetors. I'd be very interested to here more about your car. It may be that it was a special import. Does it have twin SU carburetors? Can you post some photos I understand that the 7R is similar to the 4R but has a bigger bore a shorter stroke. If this is the case you could replace the crank and conrods with those from a 2R or 12R. In effect you will be stroking the engine and increasing the capacity. Hope this helps John