Hammering pistons out of a Buick Nailhead—again - Hagerty Media

The Buick Nailhead has been a thorn in Davin’s foot for months now, causing him pain with every step in the Redline Rebuild process. The crew’s last trip to the machine shop was the most painful, where we learned that the cylinder heads were unusable, and the block required extensive repair work to save. The most economical solution—sourcing parts, in the form of a used block and head—meant now Davin had to take a few steps back to ultimately move ahead.

When Davin started this teardown, the Nailhead resembled something more akin to a greasy boat anchor than a 401-cubic-inch V-8. Almost every part that came off the engine put up a fight, from the torque converter to the pistons, which meant big hammers and torches proved the most used tools in the toolbox for what seemed like weeks.

When the replacement 401 long block arrived, Davin figured disassembly would be a quick and easy process. After all, this new purchase turned over by hand, and nothing was gunked up or stuck to get in his way. Unfortunately he made the mistake of expressing that thought out loud, which of course meant the teardown ended up hitting a big roadblock: When he tapped the pistons to coax them out of their bores, they didn’t want to leave.

“It was a ridge at the top of the cylinder. Not uncommon to see on high-mile engines,” Davin says while staring at the oily mess. “The piston rings wore the cylinder wall, but since the travel of the piston is not all the way to the top edge of the cylinder, it leaves a ridge of material that makes it tough to remove pistons sometimes.”

Thankfully, the process proved still significantly less of a nightmare than last time, and the sledgehammer and air chisel stayed in the toolbox. With the crank, pistons, and camshaft pulled, this block is now ready for a bath in the hot tank at the machine shop. With any luck, what comes out on the other side will be one big step closer to a beautifully rebuilt Nailhead.