Sorry, but I can't find any information on Westfield mowers or tractors. I can't help you much will the info you are providing. We will need some number off the unit itself. If you have no numbers, the only other way to figure out what you have, is to contact Honda with all Honda numbers and they may be able to check their records to see where that engine was used. If you do this, make sure you provide them with all Honda numbers, not just GV400, or they will not be able to help.