Mike gives us an overview of what goes into a Twin Cam cam compartment inspection and upgrade of the cam chain tensioner chain.
As many of us are already well aware, from 2000 to 2006, Harley Davidson’s spring style cam chain tensioners were a complete disappointment to say the least! Eventually, Harley began suggesting that the tensioners be inspected at 30k miles. Hardly helpful. In the real world, independent shops (like us) have seen spring cam chain tensioners fail with as little as 15k miles. On the other hand, we have had customers go upwards of 60k miles without failure. We guess that’s where HD arrived at suggesting inspection at 30k. We also suggest you watch the Cam Chain hydraulic Tensioner Upgrade Project Videos Here.
Regardless of which style upgrade or vendor is being considered, there are a few things that are extremely important to take into consideration. Inner cam bearings must be upgraded to Torrington bearings. It is imperative that the bearings are replaced correctly and with the correct specialty tool. If inner cam bearings are damaged during removal or installation, debris can fall into the crankcase. This will inevitably result in pulling the motor out of the frame so that the crankcase can be separated. This, in order to retrieve the debris and properly clean the compartment.
Regardless as to whether or not you will be using adjustable pushrods; if rocker boxes are leaking, we strongly suggest addressing at this time. If adjustable pushrods are not needed for a conversion, stock Harley Davidson pushrods are good quality and fine to reuse. It’s important that the hydraulic tappets are replaced. Tappet failure can be catastrophic to a motor. Like a bad cam bearing or a broken spring tensioner, debris from a broken hydraulic tappet can spread throughout a motor. It can score or completely seize an oil pump. If oil pressure is lost, you have catastrophic damage will be inevitable.
If considering a gear drive conversion, pinion shaft run-out will need to be measured. If run-out exceeds the manufacturer’s specified limit, flywheels will need to be replaced or re-trued; or a different conversion will need to be installed.