Saturday, 22 November 2008

Vintage Thing No.35 - the flathead Ford V8

There aren't many engines that burst out of the engine bay and assume a life of their own but the flathead Ford V8 is definitely one of them. Look - there's one that's escaped even now, wriggling across the pebbles of my scrap buddy's drive. As Rob puts it, this engine won World War 2. That's a bit of an exaggeration but it was really what the flathead Ford V8 got up to afterwards that makes if of interest to me and marks it out as a Vintage Thing in its own right.

You've probably heard of the phrase Anglo-American Bastard? It covers a wide variety of British cars that used big, low-stressed American engines in stripped down chassis and lightweight bodywork. This trend began before World War II with things like the Brough Superior and Railton and carried on right up into the sixties with the Gordon-Keeble, Bristol and Jensen.

Some of these cars weren't so much Anglo-American bastards but more love children.

Liberated from their heavy American chassis and bodywork, these engines enjoyed outstanding performance for their day and were really early hot-rods. The early ones were usually powered by Hudson flathead straight eights. Then Ford UK got in on the act and producer factory version in the shape of a Ford Pilot. By the time World War II broke out, there were many Ford V8s powering private motor cars. During World War II, this doughty engine was enlisted and powered everything from staff cars to artillery tractors. After World War II, the Ford V8 embarked on an illustrious competition career.

You'll've heard of Rob before. He is my scrap buddy and is mildly obsessed with Allard trials cars but in a good way. Sydney Allard was a larger-than-life character who spotted and started to exploit the performance potential of the Ford V8 in the late 1930s. He began by making mud-plugging trials specials, initially just for himself and a few friends, but then he began series production. He also entered the history books when he won the Monte Carlo Rally in a car that he had designed and built himself, a feat that nobody else is likely to ever match. During the war, his garage serviced all sorts of military vehicles powered by this engine. After the war, the Flathead Ford V8 was available cheaply as ex-army surplus.

But why's it called a flathead? It's because it has its valves on the side of the cylinders. In the case of the Ford V8 they nestle down in the vee of the engine. It's a very simple layout but is not very efficient. The combustion path is tortuous and lopsided. Overhead valves are much better in this respect but require a more complex head casting. Cylinder heads are on side valve motors are little more than slabs of iron or aluminium, hence the nickname flathead.

Let's just do the numbers on this engine. Cubic capacity is 3,622cc (221 cubic inches if you're over the other side of the pond) with a 77.72 x 95.25 mm bore and stroke. On a 6.2 to 1 compression ratio they put out 90 bhp. Mercury V8s had a bigger bore of 80.96mm to give 3917cc and 100bhp on a 6.75 to 1 CR. These were shared with Ford trucks and later with Fords cars. To perpetuate Mercury's premium brand image, and performance reputation, the V8 was stroked to a full four inches to give 255 CID (4184cc, 80.96 x 101.6) that ultimately gave 125 bhp on a 7.2:1 CR in production form.

We don't talk about the 2227cc V8. This was a small bore taxation special that found rice pudding skins intimidating. It was replaced in 1941 by a larger capacity straight six but was popular in midget racing in the US. Under the UK's pre-war RAC rating, which was calculated on bore size, the 66.04 x 81.28 engine was dubbed the V8-22. It's bigger 3.6 litre brother was the V8-30, which was much more expensive to tax annually. Still, phwaaoorr, though, eh?

"Enjoying the new crankshaft, gentlemen?"

The first flathead Ford V8 appeared back in 1932 and it was remarkable for being the first monoblock V8 engineered for mass production. V8s were by no means a new idea but combining the crankcase and blocks together in a single casting was. This was the key to making it cheap enough to produce and viable for Henry Ford to use in a family car. He picked a handful of his best engineers and housed them in an authentic replica of Thomas Edison's inventing shed. Suitably inspired by these surroundings, engineers Carl Schultz and Ray Laird worked closely with head of the pattern shop Herman Reinhold to build the prototype. Once the engine was up and running, however, it needed the determination of production manager Charlie Sorensen to work out a way to insure that 54 separate cores stayed put in the mould. All of them had been exactly the right place at the valve sections and cylinders in the engine block. It was only after many failures and sometimes days when the Ford factories produced only scrap that eventually the production problems were solved and Charles Sorensen became henceforth known as "Cast Iron Charlie."

There then followed an anxious time as production slowly built up to meet demand that this was the height of the depression. Between November 1931 and March 1932, the vast Ford factories produced no cars at all while Sorensen of the rest of Ford's team raced to solve the production problems. It was only Henry Ford's fast personal wealth that tided the company over until the new car had overcome initial buyer resistance.

The Ford flathead V8 was an early incarnation of the world engine concept. It powered American, Canadian, British, French and Australian vehicles and Rob has an ex-NATO example for one of his Allards that was built in Clermont-Ferrand in the 1960's.

Because of its thick walled cast iron engine block, over-boring of the cylinders is quite feasible and capacities of up to 286 CID or 4691cc are possible. I found Vanpelt Parts and ServiceAmerican website and they quote a four and one eighth inch stroke crank as well as the stock ones.

Ford flathead V8 capacities (in metric, I live in Yerp you know)
Stock Stock Special
95.25 101.6 104.78
Stock 77.8 3622 3864 3985
Stock 80.9 3917 4178 4309
Special 84.1 4233 4515 4656
Special 85.7 4395 4689 4835

The example on Rob's drive has the desirable - count them - 24 stud head. When tuned for high performance, standard heads, which are little more than thin slabs of metal, can warp. (That's another reason for calling them flat heads - it encourages them not to warp.) More studs aid the seal between head and block and prevent blown head gaskets. This engine also has the rare twin carb Allard induction manifold.

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