Engines Part 2: The Flathead

Long a dream of Henry Ford's, the V8 was offered in 1932. Examples of V type engines existed long before this, but Henry's breakthrough was in casting the engine block in one piece. That original engine produced 60 hp, which over the years was increased (some modified flathead engines produce over 300 hp). The reason it is called a flathead is due to the valve arrangement. A single camshaft, driven by gear, is located in the valley between the cylinders, and the valves driven off of that cam are located in the engine block structure. For that reason, and since none of the valve train is located outside the structure of the block, the cylinder heads are simply that. The lack of valve apparatus in them means that they have a relatively low profile; hence a "flat head".

There is no valve adjustment on a stock Ford flathead. The gap between the valve stem and the tappet is set once forever by grinding the end of the valve stem to create that perfect gap. So, no adjustment, no gap settings, no maintenance. In the later days of the flathead there were adjusters applied to flathead valves, but the process of adjustment means that the carb and the intake manifold have to be removed to even get at the valves.

The lore of the flathead engine is large, and there is a ton of information about them on the Net. Suffice to say, the relative lightness of the powerplant and the wide availability of parts made it The engine to use for performance, from racing to hotrods. In fact, Jud, in working for Bob Estes Lincoln Mercury was very much involved with flatheads from his earliest days there, not only helping to prepare Estes' cars for the Panamerican road races of the early '50s, but in trying to establish the flathead as a winning engine in oval track competition. In the former, he had success, but in the later he could never quite accomplish this, and for that reason went over to using Offenhauser engines in building his race cars. The last flatheads were made in 1954, with Ford moving to an overhead valve arrangement in an engine referred to as the Y block (there were overhead valve conversions of flatheads done in the later days of the flathead. Known as Ardun OHV conversions, created by Ardun Duntov, they did improve the performance of the engine. In fact the first Allied car, used by Burke and Thompson had an Arden head conversion on it).

The engine I've chosen for my car is a Mercury 239 cubic inch. It dates from 1951, and was in remarkably good shape when I bought it. I did have it checked for cracks (block cracking because of heat issues is notorious in these engines), but there were none. I had the cylinders very lightly honed (to take off the wear rings), and the crank lightly turned, but very little else. Of course I had new pistons, valves, main and rod bearings put in as well as a new timing gear put on. There are an enormous amount of aftermarket items to improve the performance of the flathead. Some of these, like the OHV conversion heads, are extremely prized today. My intent will be to add aftermarket heads, an aftermarket intake manifold to accept dual carburetors. Because of the hoodline of the car, I will need to locate the generator on the side of the engine as compared to the top mount. I'm also considering some sort of side draft carburetor for the same reason.