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.
First of all,the side loading from that wavy washer can cause friction and premature wear problem.
second of all,Oil volume problem Because of the small size of the stock oil pump.
Third of all,"Wet Sumping" problem because of lacking of scavenging.
The above three points 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. The TIGERSGATE oil pump comes with a high efficiency, Billet Aluminum, 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.
Specification:
Brand: TIGERSGATE
Condition: Brand New
Replaces HD# 26035-99A
Item Name：High Volume Billet Aluminum Oil Pump
performance：
Cooler oil & engine temperatures
Increases oil pressure
20% increased feed volume
60% more scavenging (return) volume
Accessory：Complete with all the necessary hardware & gaskets
Material：Made from billet aluminum
Package List：
A set of High Volume Billet Aluminum Oil Pump