I bought one of the original Tower .46 many years back and I also had a similar problem. For me the engine ran EXTREMELY hot even with 20+% Catsor. After consulting with the late great George Aldrich he suggested I put in a couple of the shims that the engine came with. Well, what do you know? The engine no longer ran hot and to this day the only evidence of that frustrating incident is the blue head is a bit lighter. This engine has run great ever since with awesome power and smooth, low idle. Try putting in some shims- that might help.