Enjoy Buick Straight 8 stories, opinion, and features from across the car world - Hagerty Media

One of the fascinating aspects of large projects like this Buick straight-eight rebuild is that setbacks are only temporary; given the laundry list of smaller tasks, there’s always some way to make progress. Davin is still brainstorming solutions for the cylinder head assembly problems that cropped up last week, so this week he forges ahead by installing most of the rotating assembly into the engine block.

Of course, it never goes that easily. Davin has to chase the threads on the oil galley plug on the back of the block before he can install the adapter plate for the bell housing. Of course, with a cleaned and painted engine block, this is not the ideal time to create cutting chips; Davin meticulously removes the fragments from chasing that thread so they don’t run through the engine on its first startup. Luckily, there is an access port next to the plug opening, so a few blasts of compressed air and a small magnet take care of the dangerous material.

In go the cam bearings, and Davin measures the crankshaft and main bearings to ensure proper oil clearance. He does this to double-check that the machine work was done correctly and that the bearings are marked properly. Taking some extra time here saves the potential headache of assembling the bottom end of the engine and discovering that it doesn’t spin or that it is way too loose.

A final piece of good news is that the valve debacle has been resolved. As Davin tells it, the Buick 400 V-8 valves that he is using in this straight-eight are manufactured in two different styles, and it was pure luck of the draw that, of those two variants, the first valve order contained the wrong one. A quick phone call got the proper pieces to our doorstep in no time, and now the assembly of the cylinder head can continue as planned.

If you want to see what hurdle will pop up next on this engine—we all know it will happen—be sure to subscribe to the Hagerty YouTube channel to receive notifications with each video that goes live and never miss a problem-solving minute.

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Enjoy Buick Straight 8 stories, opinion, and features from across the car world - Hagerty Media

The Buick straight-eight is looking good after its paint job last week, but that doesn’t mean the assembly process is running completely smoothly. Davin got all his ducks in a row before starting this project—just like he does each time—and the cylinder head still presented him with two problems which weren’t immediately solvable.

“There is always a chance for a situation like this, even when using all the “correct” original parts,” says Davin as he stares at a table holding a plethora of springs, shims, and valves. “The fact we are using a few non-original pieces only elevates the chance.”

The problems arise from the retro-fit valves Davin’s chosen for the Buick 400. The seat diameter is slightly larger, which makes for better airflow, but the stem is causing two issues. The first is a slight discrepancy in length, which Davin resolves with an extra shim under the valve spring. No big deal. The second problem with the stem, though, lies in a step machined just below the lip for the keeper. The step is in the perfect place to catch on the valve stem seal as the valve cycles through its travel.

In addition to troubleshooting the valves, Davin is also confronted with an interference fit between the inner valve spring and the cylinder head. The inside diameter of the spring is just a bit too small and gets hung up on the lower portion of the casting for the valve guide. Davin has a cutter that he thinks will solve the problem, but he hopes cutting a relief won’t cause more problems.

Such are the trials and tribulations of engine building. Problems and setbacks pop up, often at what seems the worst possible time. Davin and the team will need to do some research to build this Buick correctly, but the time investment is worth it for an engine we can trust and don’t have to rebuild after a few drives. Be sure to subscribe to the Hagerty YouTube channel to discover how Davin tackles the challenges the Buick straight-eight throws his way!

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