SAE J 624:2001-07-31

This SAE Recommended Practice applies to domestic four-cycle air- and water-cooled engines having a maximum of 14.9 kW (20 hp) or less in power output and/or 0.82 L (50 in3) or less in displacement, with horizontal or vertical crankshafts. The engine shall be furnished with a minimum of either a tapped exhaust port or two tapped holes and flat port face making possible use of a threaded connector or one of the flanges shown in Figure 1. Exhaust flanges are sized to be used with mild steel or aluminized steel butt-welded tubing.