Tecumseh HH120 HH150 OH160 Piston and Rings 3-1/2 In 32238B

Standard size piston and ring set for the Tecumseh HH120, HH150, HH160 and OH160 engines. 3-1/2 inch bore. Replaces Tecumseh 32238B, which supersedes the earlier 32238 and 32238A. Tecumseh's number for the piston supplied together with its rings is 34511, and the standard ring set on its own is 32241. THIS IS THE 3-1/2 INCH BORE AND NOT THE HH100. The HH120 is 3-1/2 inch and the HH100 is 3-5/16 inch. They are not interchangeable in either direction, and the HH100's own standard piston is 32001C with the 32004 ring set. The two engines look alike and went into the same machines, so read the model and spec number off the engine plate rather than going by the machine it is bolted into. WHICH ENGINES THIS COVERS. The same 3-1/2 inch bore runs through the HH120 at 12 horsepower, the HH150, the HH160, and the OH160. HH means horizontal heavy duty cast iron and OH means overhead valve heavy duty cast iron, so this piston spans both the L-head and the overhead valve versions of the big cast iron single. The HH120 itself is 3-1/2 inch bore by 2.875 inch stroke, 27.66 cubic inches. STANDARD SIZE - MEASURE BEFORE ORDERING. This is the standard bore piston. After sixty years most of these cylinders have been bored at least once, and an oversize cylinder needs the matching oversize piston. Tecumseh gave each one its own number for .010, .020, .030 and .040 inches over. Measure the cylinder. ON ASSEMBLY. Check ring end gap in the cylinder the rings will run in rather than the old one, and check side clearance in the piston grooves. Check the cylinder head for warp on a flat surface while it is off. The piston pin retaining rings are Tecumseh 31919 and are a separate item worth having on hand, because sixty year old retainers do not always come out in one piece. AVAILABILITY. Tecumseh closed its engine division in 2008. Standard size parts for the cast iron engines are the scarce end of what is still in circulation.

• STANDARD SIZE 3-1/2 INCH PISTON AND RING SET - Replaces Tecumseh 32238B, the standard size piston and pin assembly for the 3-1/2 inch bore, and supersedes the earlier 32238 and 32238A. Tecumseh's number for the same piston supplied with its ring set is 34511, and the matching standard ring set on its own is 32241.
• THIS IS THE 3-1/2 INCH BORE - IT WILL NOT FIT AN HH100 - The HH120 is 3-1/2 inch. The HH100 is 3-5/16 inch. A piston three sixteenths of an inch too large does not go in, and the HH100's own standard piston is 32001C with 32004 rings. Read the model and spec number off the engine plate before you order.
• IT ALSO FITS THREE MORE ENGINES - The same 3-1/2 inch bore runs through the HH150 and HH160, and through the OH160, which is the overhead valve version. Tecumseh's own OH160 parts list calls out this same piston. So this covers 12, 15 and 16 horsepower across both the L-head and the overhead valve cast iron engines.
• STANDARD SIZE - MEASURE THE CYLINDER FIRST - This is the standard bore piston. These engines are sixty years old and most have been bored at least once, and an oversize cylinder needs the matching oversize piston: .010, .020, .030 and .040 are each a separate part number. Measuring once is cheaper than a return.
• WHAT TO DO WHILE THE ENGINE IS OPEN - Check ring end gap in the cylinder the rings will actually run in and side clearance in the piston grooves. Check the cylinder head for warp on a flat surface. The pin retaining rings are a separate Tecumseh number, 31919, and are worth having on hand because the old ones do not always come out intact.