If you have the valve covers off, and the rocker arms off, they do indeed look like nails stuck in a board.
This is a relatively new name, I don't recall them being called that when they were in production (1953 - 64). They were designed before the Horsepower Race got going. Their designer chose a strange head design for no good reason that I ever heard of. One of the drawbacks was that it only had room for small valves. Maybe they thought it would not matter on a mildly tuned luxury car engine, in fact it caused problems from 1957 on, if not earlier. 57 Buicks were hard to tune, they had a radical camshaft that made it hard to get a smooth idle unless everything was exactly right. Buick's effort to overcome the breathing disadvantage of the small valves and crooked exhaust ports.
They were very torquey in their day and that is why Range Rover bought the design and used them for some time.
To keep the engine narrow Buick put the valves in the inside 1/2 of the chamber limiting the valve size. Hence the valves looked more like a nail than other motors.
This post proves some people have no idea what they are talking about........................................ Range Rover, really?.................Heads nailed down!!
Pretty sure it was the aluminum 215 that was used in the Range Rover - or at least patterned after - but what do I know Nailheads must have been good for something. they were used a lot in the 60's for a lot of different applications. Tommy Ivo had a fondness for them
Don't matter if it's old, I'm old and learned something new. Also, those motors look good dressed up and open hood !
Not to beat an old and long dead horse but the combustion chambers on a nailhead Buick engine were not just an afterthought. The Buick engines were designed for torque and the spark plug is centrally located just like a hemi but without all the hype. Buick engineers called this design the "Fireball 8" even when it was used on the straight 8 engines. The principles of the design are still used today to promote high swirl combustion chambers and as a side effect the old Buick engines were very octane tolerant. The head design is so good that hardened seats are never required on nailheads even running non-leaded fuel. The only reason I ever heard that they were called nailheads is because the valves are straight up and with the valve covers off they look like a row of nails which has nothing to do with the valve size. A 425 CID nailhead has valves larger than some hi-po Chevrolet engines. Yes they do dress out nice, just look at my avatar!
A 425 buick had 1.875 intake and 1.5 exhaust hardly big for 425 inches the 322 had 1.75 and 1.25 valves hence the hail valve name.
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