Re: Balmar Pulley Size
I think I have the same engine Perkins 154 and the same ? alternator Balmar 100 amp as you. As long as the belt is not bottoming out in the pulley groove you are OK.
I get the belt "dusting" if it is not at the top end of tight and a new belt. . Once it has slipped and dusted tightening it does not get it to stop slipping.
I just carry several spare top quality belts and change them if I get the belt dusting. Keep it tight and it drives OK.