In the Redline Rebuild garage, any time we’re tearing down an engine we start with disassembly before making a trip to the machine shop. Davin has done this routine enough times that he often has a good idea of what the experts at Thirlby machine shop in northern Michigan are going to tell him the engine will need once the parts cleaned and inspected. The 1951 Buick straight-eight we’re working on came apart easy enough, but it was hiding some unsavory secrets that led Davin to believe that this trip to the machine shop was not going to be a simple in-and-out process.
Though this engine was in significantly better shape than past Redline Rebuild candidates, the overall condition was grimy at best. Once at the machine shop, Davin took a break in the action to talk us through the four-step process that both the engine block and heads experience before the real inspection begins.
The Buick straight-eight had heavy pitting and taper in one of the cylinders, and the others were in only marginally better shape. Davin assumed all eight of the cylinders would need to be bored oversize and have sleeves hammered in. Before that diagnosis took place though, the block needed to be cleaned.
Each of the large green cabinets presented in the video serve a separate purpose. The first is essentially a dishwasher, which uses detergents to break down and wash off the majority of the grease and oil on the parts. Then a hoist snatches the block up and moves it over about 10 feet into the second cabinet, which is a furnace. The goal is to cook off all the paint and remaining grease. Then the block gets assaulted with steel media that polishes away any remaining imperfections. Of course, as Davin notes in the video, you want to get absolutely all of that steel media out of the nooks and crannies of the engine before reassembly. Which is why the last cabinet rolls the block at various angles and blasts it with compressed air to break up those lingering pockets of material.
Then, only after all that, was the block ready for a real inspection. A magnet and iron filings confirmed the block is crack-free, but Thirlby’s resident bore expert Mike still had bad, if not unsurprising news for Davin and the Redline crew—they’ll need to bore the cylinders out and place sleeves in all eight holes.
On the bright side, for you engine nerds, it’s a process that a future Redline Update episode will walk through step by step. Hooray! Of course, if you don’t want to miss an oil-soaked minute be sure to subscribe to Hagerty’s YouTube channel to receive updates with each new video that goes live.