This recommended practice applies to domestic four-cycle air- and water-cooled engines having a maximum of 20 hp (14.9 kW) or less in power output and /or 50 in3 (0.82 L) 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. Exhaust flanges are sized to be used with mild steel or aluminized steel but welded tubing. Recommended port tap sizes and exhaust flanges for both horizontal and vertical crankshaft engines are noted Purpose - This SAE Recommended Practice is intended to define tapped and flanged exhaust connections for small gasoline engines.
SAE J624-1984 history
2001SAE J624-2001 Tapped and Flanged Exhaust Connections for Small Engines
1989SAE J624-1989 Tapped and Flanged Exhaust Connections for Small Engines
1984SAE J624-1984 Tapped and Flanged Exhaust Connections for Small Engines