Abstract: A fin-tube block type heat exchanger in which extruded tubes are alternatingly arranged with corrugated fins, the fins being shorter in overall length than the tubes and having elongated bars at their ends serving as spacer bars between the tubes. The side walls of the spacer bar preferably taper towards each other such that the thickness of the spacer bar at the inner wall is less than the thickness of the spacer bar at the outer wall. The side walls include one or more recesses or grooves extending lengthwise with the spacer bar into which low temperature melting alloy is captively inserted. During brazing, the alloy melts and is drawn by capillary action into the space created between the tapered side walls of the spacer bar and the facing surfaces of the adjacent tubes so that a complete joint is formed between the spacer bar and the adjacent tubes.