ACL's main bearings are made of a softer metal so that you don't wear out your crank or engine block. Additionally, a thin layer of oil lubricates the connection between the bearings and the crank allowing the crank to "float" and reduce wear. Proper support via main bearings is crucial to prevent oscillations and wear that can damage the crankshaft and other components as the motor moves further out of balance.
Bearings with extra oil clearance will absorb the stress of higher horsepower motors greater, but will see increased wear during start up. We recommend these be purchased by experienced professionals only.
Any returns for an exchange or refund will be allowed within 30 days from the receipt of your order and must be authorized prior to shipping with an RMA Number (Return Merchandise Authorization). To receive your return instructions and RMA# please use our online form under Returns and Exchanges! Once you receive your return instructions please ship out the item at your earliest convenience and provide the tracking number to your customer service rep. The customer will be responsible for all shipping fees. Before shipping your product back please make sure you package it up exactly how you received it and in all of its original packaging. All items must be in brand new and resalable condition. Once the item is received it will be inspected and a credit will be issued accordingly. All returns are subject to a 15% restocking fee. Any returns received without an RMA# will be charged a restocking fee and any shipping fees associated with the return. An item that does not ship directly from IIR's warehouse is considered a "special order" item and no returns will be authorized.