Inliners International Forums General Discussion Engines 261 Remote oil filter line size

261 engines had 2 options. There is a 1/2" diameter pin that could be left in the flush position for say a fleet vehicle with no oil filter (like the old days). Once the pin (located by the 1/2" NPT oil line fittings) is driven in 9/16" then a full flow filter or a bypass line connecting the NPT fittings is required as ALL the oil is filtered before going to the engine.