If you have to work on an engine, this is the first part you need to install. Twin Cams have a small die cast gerotor oil pump that has a wavy washer (Belleville style) to pre-load the pump gears against the cam support plate and pump housing. The side loading from that wavy washer can cause excessive friction and premature wear and give a lot of problems. Because of the small size of the stock oil pump, they often have problems getting enough oil throughout the engine, especially to the valve train components. Another problem is the lack of scavenging, causing "Wet Sumping". Instead of returning to the oil tank, the oil builds-up in the crankcase and cam chest, causing excessive friction/power loss and the oil becomes like "peanut butter". This can result in oil being forced out the breather, air cleaner contamination, oil leaks, loss of oil supply, lifter clatter, component wear and even engine failure. Zodiac comes with a high efficiency, billet, anodized, bolt-in replacement oil pump that provides 40% more supply volume and 60% more scavenge volume than the stock oil pump on 88 CI Twin Cams and provides 20% more supply volume and 30% more scavenge volume over the Harley's improved 2006 Dyna and all 2007 and later Twin Cam oil pump. Large diameter gerotors and aerospace materials are used and the parts of each and every pump are hand matched to ensure close tolerances to create a high efficiency pump, without the need for a high friction wavy washer. This will provide the Twin Cam engine maximum reliability and longevity.