M8 Oil Pump Upgrade

Before we get to the M8 oil pump and S&S cam, there are two crucial things that need to be addressed.

First, it is vitally important to measure the crankshaft run-out. A dial indicator is needed to take this measurement. For 2007 and later Harley Davidsons, the run-out should not exceed .012″. Twelve thousandths is actually a lot, considering that the spec for earlier Twin Cam models is .003″. If run-out is out of spec, the flywheels need to be removed so that they can be professionally rebuilt and balanced.

The other important thing to address is the cam bearing. The stock cam bearing should never be reused. It is a caged bearing. It needs to be replaced with full roller bearing, especially when installing a higher lift camshaft. Mike uses a Jim’s specialty tool to not only remove & install the cam bearings but also to take measurements for cam depth.

Mike has the latest Harley Davidson M8 oil pump which has superseded the original M8 oil pump. The latest oil pump now has a seal that mates against the main bearing cavity. The seal that this achieves promotes better oil scavenging. The new M8 oil pump is assembled with assembly lube and installed into the cam compartment. It is of utmost importance that the pump pushes fully into the pickup o-ring.

Mike bleeds the new S&S lifters with an oil can and then leaves them soaking in fresh oil while moving on with the cam install. Again, assembly lube is used to coat the cam bearing, cam shaft, and the cam plate.

It is crucial that the factory torque sequence and torque specs are being followed and that the motor is being periodically rotated when installing the cam plate and M8 oil pump hardware. If the oil pump is not correctly aligned, it can bind creating a loss in oil pressure or possibly catastrophic damage.

With the cam plate installed, Mike installs the stock cam sprocket spacer and temporarily installs the cam and crank gears. The gear offset, or alignment, is checked with a true straightedge. If the offset distance is more than .009″, a different size cam gear spacer will need to be installed in order to compensate. Once the correct gear offset is achieved, the gears are removed.

Mike assembles the gears and chain with the timing marks correctly aligned. The cam and crank bolts are prepped with red Loctite and torqued to factory spec. With the cam compartment completely assembled, Mike is ready to move forward with the motor upgrade.

Next up, we will install lifters, lifter covers, S&S Quickee pushrods, and the cam compartment cover.

Related Videos:
Cam Gear Drive Conversion (Twin Cam)

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