Cont

Cont. from page 5

walls get the more they flex, and if you can keep the walls stiff everything stays in place." As effective as a 1/2-inch stroked crankshaft is for waking up the flathead, it's not an easily found, off-the-shelf item. Depending on the stroke desired, a stock crank could be either offset ground or welded and then ground for a long stroke, such as a 1/4-inch increase. But as we said earlier, hot rodders were given a big gift in 1949 when the Mercury crank was blessed with a 4- inch stroke - 1/4-inch more than previous Ford and Mercury crankshafts. Even today, this is the preferred method for increasing the output in a streetable motor, with good cast-iron Mercury crankshafts selling for a couple of hundred dollars. Be prepared to pay more for a tougher, cast-steel crank. We'll deal with the subject of increased stroke in more detail in Part 2, but we bring up the Mercury crankshaft option just in case you are about to begin your parts hunt. But before you make any big decisions, read the Sidebar teaser to see what's ahead for the hot flathead.

CONNECTING RODS

The 59 series engines were equipped with floating connecting rod bearings which are best avoided. It's an outmoded design with definite shortcomings, not the least of which is a very high price today - about $200 per set. Add to that the news that Federal-Mogul - the only manufacturer of this style bearing - is discontinuing them, and the bearings and the rods that use them are even less attractive. But not to worry; again in 1949, Ford provided a modern locked- insert-bearing rod for both the Ford 8BA and Mercury CM engines, for the same journal size as the 59 engines. For rodders raised on modem over- square high-revving engines, the Ford and Mercury rods appear to be frighteningly delicate, while in reality they are amazingly tough and well up to the rigors of the duty they'll see in a streetable built flathead that's very likely to be twisted no tighter than 5000 rpm if that.

As it is for any successful engine building project, the Ford-Mercury flathead must begin with sound components. For a modem engine, excellent blocks, cranks, rods, and heads are plentiful and inexpensive. For the flathead, with essential components ranging from 47 to 58 years old, the ratio of non-serviceable to serviceable --- three or four to one --- and the cost of the cleaning and testing to reach a point of certainty account for the price of a sound and buildable block - roughly a thousand dollars. Considering the total cost of a professionally built flathead today, to start with anything less is foolish, and engine pros like Dave Tatom won't even consider cost-cutting shortcuts in such critical areas. And neither should the home-builder try to find transient economies by eliminating any of the critical cleaning and inspection steps. With a sound foundation on which to build, we'll turn our attention in Part 2 to spec’ing what may well be called the ultimate street flathead, with the flexibility and reliability of a modern pushrod engine-- and torque output to make the small- blocks envious. We'll learn about the flathead's "sweet spot" and how to take advantage of it. -Mike Bishop

An overlapping pin repair such as this is an excellent method when the crack doesn’t extend down into the valve pocket

Welded repairs are necessary when crack damage extends down into the valve pocket and runner where the parent metal is not thick enough to support a pin repair.

Dave Tatom’s personal flathead is as unfussy as a modern small block—and sounds a whole lot better to some ears.