Wes Duenkel
February 15, 2018

Just like a solid foundation is important for a sturdy house, a well-prepped engine block is critical for a motor make big power—and do it more than once. A professional engine builder offered to show us a few tips and tricks on how they prep and clean an engine block before making big horsepower.

The subject is a Ford Performance Parts BOSS 351 block serving as the bases for a high-boost, 2,000 wheel horsepower engine build. Given what’s in this block’s future, they didn’t want to leave any stone unturned.

While the BOSS 351 block is an excellent part right off the pallet, there were a few things a one should consider, such as knocking the sharp edges off of the block features and adding a chamfer to the top of the cylinder walls. An experienced builder showed us some handy tools he uses to ready a block for mega horsepower.

1. The builder used an abrasive cone to add a chamfer to the top of each cylinder. This helps the delicate piston rings into each bore upon assembly.

2. The builder also used a die grinder to chamfer the edges of the oil drain back holes. He added, “Even though this block has some big drain holes, it’s still a good idea to smooth them out.”

3. Usually the builder will also chamfer the bottom of the cylinders, but this Ford block already had this feature. “This chamfer keeps the piston skirts from scraping the bottom of the cylinders when they rock through the engine’s rotation.”

4. The brush on this special oil gallery cleaning tool cleans debris from the oil galleries, and the water and air pressure washes it away.

5. This photo illustrates how any debris left in the oil galleries is flushed right to the main bearings at engine startup. The builder explains, “Clean oil galleries can make or break an engine build.”

6. After washing the block and drying it out with compressed air, the builder immediately applied penetrating oil to the cylinder walls. “If you don’t oil the cylinder walls after washing, they’ll start rusting immediately.”