Greasy to gorgeous: Buick Straight 8 Fireball engine rebuild time-lapse | Redline Rebuild - Hagerty Media

The Redline Rebuild process is never easy. Taking what is typically a heap of an engine and returning it to its former glory—or better—requires patience, time, and resources. When he first saw the Buick straight-eight, Davin thought it couldn’t possibly be worse than the boat anchor of a Buick Nailhead V-8 he tackled in 2019. If only he had known.

“This straight-eight was a runner, but it was real tired,” Davin says. “The goal of producing hot-rod looks and performance gave me some leeway in planning the build, but the hurdles I came up against were going to be problems even if we went back to a stock setup.”

The long-block came out of Hagerty’s 1951 Buick convertible, which had been languishing in the corner of the garage for years. There was great debate regarding the fate of the car and, consequently, that of its engine. We decided to create a period hot-rod and thus pulled the straight-eight and sent it over to Davin and team for a refresh and restyle.

“Since it was already a running engine, the teardown was pretty quick. There were no real signs of damage, but the block was plain worn out,” Davin says.

All eight cylinders received a heavy cut followed by pressed-in sleeves to bring the block back to serviceable condition. This process is fairly standard and made sense in the Buick’s case because the worn-out cylinders had already been bored .040 inch over stock, and larger pistons were not readily available. With the block tuned up, the cylinder head received the full machine-shop treatment as well and was cut for larger valves.

Those larger valves evolved into the first hurdle during the reassembly process, since the Buick 401 V-8 valves Davin chose are produced in two varieties. One design includes a straight valve stem; the other has a small step cut into its stem. Davin originally sourced the second variety—and discovered that the small step was perfectly positioned to destroy any valve stem seals. He had to order a second, straight-stemmed set—which was a pain, but nothing compared to the trouble he encountered with pistons.

The pistons took three rounds to get right. The first custom set came out with a goofy design that didn’t spark Davin’s confidence. The second set looked great, but the casting was incorrect and the piston rings didn’t fit. Finally, the third set worked, and he could button up the rotating assembly.

Once the long-block was built, the period-correct Edmunds intake manifold and modern tubular split header were carefully bolted into place, a process that required the use of all three of Davin’s arms—and he might have used a leg when the camera wasn’t rolling.

“That intake and exhaust manifold situation was something else,” Davin says. “For sure, something I am not in any rush to do again.”

At last, in this video, the engine moves over to the run stand for a test-fire and break-in before it heads back to its home in the Buick chassis. Success! The split manifold sound is spot-on hot-rod. Between the sound and the look, this straight-eight might be one of the coolest Redline Rebuild engines so far. After all, who knows what Davin has up his sleeve for 2021?