The paper presents an example of the possibility of modifying a heat source model, which resulted from the differences between the shape of a standard model in the shape of a double ellipsoid and the geometry of a liquid metal pool in the metal-cored arc welding process. Due to the fact that the heat source models implemented in the software do not always allow to reproduce the actual bead geometry, it was necessary to modify these models and signal the possibilities with which the results of the analyses can be improved. The results of modeling with a standard model in the shape of a double ellipsoid as well as a model consisting of two two-ellipsoidal models and modification of heat input by heating the selected elements of the model mesh are presented. The use of the proposed solutions of heat source models, which allow to reproduce the shape of the modeled molten pool, also allows to increase the precision of the calculated maximum values of the heat cycle temperature, reducing the difference by an order of magnitude from 18-22% in relation to the values measured for the standard model, to several percent (1.2-3.3%) in the case of combined models.