Thanks for a lot of useful information. Found a NIB Tower 46 in a box of other engines I'd acquired over the years. In the box was a "spare" carb body. Recalled there must have been a reason for that so finally found this thread. Somewhere I have a couple of Irvines, a 46 and a 53. Recall they worked well so will probably get them out. Have a few kits I need to to get built and don't want to buy more engines is possible..