New Big Fords

Ford of Cologne introduced the 1183cc Taunus 12M V4s in 1962, and the 2 litre V6 20M followed in September 1964.
So the decision for a wholly American owned Dagenham plant to turn over to V engines was a natural corollary.
This is not to say that Dagenham V engines are enlarged copies of the German units.
Their later introduction shows in more advanced technical specifications, particularly in the adoption of the combustion chamber-in-piston philosophy.

Attention of engineers naturally focuses on the solution of the engine balance problems, which are the only real drawback to V engines with more than two cylinders and fewer than eight.
The expedients adopted to render the V4 acceptably smooth are now well known. No doubt the extra cost and weight of the harmonic balance shaft (which is essential in a V4) was justified by the use of these engines in small commercial vehicles where the compact size is a very real advantage. Such an expedient as not necessary with a V6, which can be balanced to acceptable standards of smoothness by means of balance weights attached to the crankshaft.

Impressive facts about the new engine are that in terms of size, power and weight it shows clear advantages. With an overall length of 288in, 9.5in. less than the in-line six, and a bare weight of 377lb as compared with 401lb, the 2.5-litre V6 develops 112 b.h.p. net at 4,750 rpm. while its predecessor produces 98.5 bhp, at 4,750 rpm. This gain in power owes everything to the adoption of a combustion chamber-piston cylinder head and advanced porting techniques.

Ford's adoption of the V6 makes good sense. There is no doubt that Ford crankshaft casting possible the economic production of the complex crankshaft necessary to ensure even firing on a V-6. The choice of a very short stroke shaft strong enough to accept unconventional, though sound, balancing methods. And the short overall length rendered the shaft free from problems of resonance and torsional vibration

With the 60deg V6, the designer is in effect tilting every other cylinder of an in-line-six sideways at an angle of 60deg about the crankshaft centreline. As a result, the crankpin of every "leaning" cylinder has to be moved around the crank centreline through 60 deg (in sympathy). Thus the virtue of the inline 6-cylinder crank with its perfect balance attained by arranging the throws mirror fashion is lost. We have instead a shaft which is in effect three pairs of throws, each pair set at 60deg to each other.
So the crankshaft on its own is in static balance but will excite the same couples as a simple 3-throw crankshaft when rotated, in that it will have a tendency to follow a double cone-shaped path. The situation is further complicated by the out-of-balance effects introduced by the angle of the cylinders.

Computer calculations, based on vec-tor diagrams, showed that the main out-of -balance force is in the plane of No. 1 cylinder relative to that piston at tdc. It has been counteracted by adding balance weights to the webs of No. 1 and No. 6 crankpins. In the case of the 3-litre engine, which has 1.43in. throws in place of the 1.18in. throws of the 2,495 c.c. engine, an extra balance weight is cast opposite Nos. 2 and 5 throws.
Additional weights are also cast into the crankshaft pulley and fly-wheel. Our diagram shows how these weights are graded out in size, and their angle relative to each pair of throws, to balance out the reciprocating weight.

Advanced techniques enable Ford to maintain wall thickness of 0.2 in. in their iron castings. Thus the weight of the largest single unit in the engine, the cylinder block, is kept down to 135lb.
Structurally, the block and crankcase casting, which is common to the 3 litre and 2.5-litre units, is similar to that of the V4.
The crankcase skirts extend 2.63in. below the crankshaft centreline. Flanged main bearing webs running down to the sump joint face give extra stiffness. Two studs retain each of the four main bearing caps, while the end faces of the caps are machined and locate against faces machined in the webs to resist side loads.

The camshaft bearing housings between the cylinder banks are cast integral with the block, and form webs in the V. The individual tappet blocks are also on the inner faces of the water jackets. This section of the engine is "roofed in" by the separate inlet manifold on assembly.

Four steel-backed main bearings, 2.5in, diameter, lined with copper-lead or aluminium tin, carry the crankshaft, thrust being taken by a washer faced with the same material on No. 2 main bearing housing. A return on the fly-wheel boss acts as an oil thrower for the rear main bearing, which has a silicone rubber garter spring seal.

With the "Heron" combustion chamber-in-piston cylinder head, piston design is always of interest. Ford use a machined combustion space to hold accurately a compression ratio of 9.1-to-1 with the 2.5-litre and 8-9-to-1 for the 3-litre Zodiac.
A slight crown is formed in the base of the combustion bowl, and the piston crown is of adequate thickness to provide good heat transfer to the ring belt. In the interest of saving weight with a diameter-to-length ratio of 0-9 to 1, slipper type skirts are used and circumferential slots are cut between the ring belt and the thrust faces to prevent heat transfer to them.

Two compression and one scraper ring are used. The upper ring is chromium plated and the second one molybdenum faced. Common connecting rods are used for both sizes of engine, the compression height of the pistons being adjusted accordingly.
The rods themselves are nickel-chrome stampings, split horizontally on the centreline with pressed-in gudgeon pins.

Although the flat deck cylinder head is described as being of the crossflow type, in that the exhaust ports are on the opposite side of the head to the inlets, this is not an exact description, since the valves are in-line with the crankshaft. However, this arrangement, dictated by the V-cylinder arrangement, does permit a good flow of water round the exhaust ports.

The Ford K-iron camshaft, running in steel-backed white metal bearings, is induction hardened and phosphate coated to ensure long life and freedom from scuffing during the break-in period. It is driven by cast-iron helical tooth gears and operates the valves by way of chilled iron tappets and short tubular pushrods. These are positively lubricated from the oil system through restrictor holes in the tappets. Following American practice, the rockers operate on individual, hemispherical mountings carried on posts pressed into the beads; they are in cast iron, the three seatings for the rocker pivot, pushrod end and valve contact face being formed in a single coining operation. Single valve springs are used, while the bi-metal valves run directly in the head. Exhaust valve head material is EN18D with an addition of columbium.

Water is circulated by a separate, belt-driven pump mounted under the right-hand bank of cylinders. It is easily de-tachable for renewal as a service unit Reversing normal practice, water is fed first into the cylinder jackets-there is a cross-over pipe between the blocks at the back of the engine-and then through metering holes in the cylinder faces into the cylinder heads and induc-tion pipe water jacket. A wax capsule thermostat ensures quick warm-up. A feature of the cooling system is the high operating pressure, 13 psi, adopted to keep down the size, and cost, of the radiator.

Oil is circulated by either a Burman or Hobourn Eaton pump driven off the bottom end of the skew-driven distributor drive shaft.
A throw-away "full-flow" oil filter is incorporated in the system. Mounted high up on the engine for ease of accessibility, it incorporates a weir to keep the system primed in the event of oil drain-away after long standing.

Depending on engine type, mixture is supplied by a single-choke 29mm Zenith 381VT carburettor for the 2-5-litre Zephyr, or 2-choke, vertical Weber 40DFA instrument for the 3-litre Zodiac.
Individual, water-heated mani-folds are fitted in each case. The single-choke unit is divided by a longitudinal partition, and the requirements of good distribution have necessitated mounting the carburettor at the front end of the manifold. The twin-choke manifold is, in effect, two separate manifolds cast as one; it has ribbed floors to assist heat dissipation from the water jacket.

As with the V4, a return fuel system is employed, to prevent fuel vaporization. An AC camshaft-driven pump supplies the fuel, surplus being returned to the tank. A metering block in the system ensures a steady pressure at the carburettor.

The 12-volt electrical system is quite conventional, except that a Lucas 11AC alternator, driven at 2.12 times engine speed, is fitted on Zodiac models. All models have negative earth.

Gearbox
Both the manual and automatic transmissions of the V6 Fords are new.
In the case of the 4-speed manual gearbox the general dimensions have been increased to take care of the extra torque of the 3-litre. The casing is a one-piece iron casting with a detachable top plate for access to the selectors. Power is taken to it through a 9-in. Borg and Beck diaphragm spring clutch.

Ford take the trouble to import their own, American made, C4 automatic transmission. It follows conventional lines with a 3-element torque converter using a freewheel stator and epicyclic gears with hydraulically operated clutches. However, it differs from equivalent British-made transmissions in the design of the governor, which incorporates extra valves to simplify matching the gearbox and to permit the use of a vacuum-operated throttle-sensing device.
Extra efficiency is obtained by omitting the push-start oil pump and there are external adjusters for the brake bands.

From the drivers point of view there is a manual low hold, useful when hauling caravans or climbing steep gradients; it retains bottom gear. Also there are D1 and D2 positions for the control. The D2 setting blocks out bottom gear and the transmission does all its work in the upper two ratios.