I have a 26 motor with a Rajo overhead valve conversion that I have running well but every time I run it the fan belt loosens up. It does have a leak less water pump.....I don't want to over tighten the fan/belt adjustment. Am I missing something that holds the fan/pulley/belt adjustment ? Any suggestions would be appreciated. Thanks in advance.
Did you try run it without the pump?
All flathead T's and many OHV T's can run without any pump if the radiator is good.
If you don't do parades you may get by without the fan too - as soon as you're running 5 mph (or more) the air flow through the radiator will be enough without any fan.
If you have to use a pump after testing without, then you must check if it turns like it should - many old pumps has a rusted and worn shaft where it's sealed - to seal it has to be tightened so much it's hard to turn. A new stainless shaft in new bushings would help.
By a serpentine belt from an auto parts store or an industrial supplier. They're just like the serpentine belts on modern cars, but a bit shorter. I run the grooved side against the pulleys. They last for many years and never stretch.
Get rid of the non Model T water pump as long as your rad is half decent. Even then, if you have a leather belt, it might loosen up regularly. I got rid of all that and now run a rubber belt on the original setup. Even with very little tension, it always works great.