Because of Henry Ford’s intractability, the flathead was compromised right from the get-go. It was meant to be a carthorse, not a racehorse. Nevertheless, the flathead is the little engine that could. Despite having three rather than five main bearings, the flathead has stayed the course. With some exotic tuning, it has been known to produce 700 hp, and not just for short bursts. A flathead with a 1946 block powered Ron Main’s Flat fire to a new land speed record for its class at 302.674 mph. The world’s quickest flathead dragster, Ron Schnell’s Slider, has run the quarter in 7.695 seconds; it’s blown flattie dyno’d at 939 hp on a 60-percent nitro load.
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So, despite its humble beginnings and inadequate provenance, the flathead can be made to perform. It’s never going to be a small-block Chevy, but it is a great little engine. According to Mike, something with a good rebuild similar to Theresa Spurlock’s engine (see Chapter 9), Navarro heads and intake, an 8.25:1 compression ratio, and a pair of Stromberg 97s should produce around 160 hp. The addition of a 4-inch stroker crank and another Stromberg 97 can push output up to almost 200 hp. However, that’s only the start. With some judicious attention to detail, particularly in the breathing department along with the addition of some speed equipment, you can easily expect a little more than 200 hp.
Several schools of thought exist regarding how to build a hot flathead, and the contention begins with the block. Some say that the NOS French block is the way to go, and in some ways it is. For starters, it’s the most modern casting available; they’re unlikely to have any cracks, they have thicker decks and main bearing bulkheads and larger main bearing caps, and they are already aligned honed. However, the French weighs in at about 30 pounds heavier than an old block, and extensive port work is necessary.
The benefits alone are enough for some, but the French comes at a price, both monetary and aesthetic. Others prefer an original 8BA. If you’re building an out-and-out race car, Bonneville car, or something similar, the choice of block probably doesn’t matter. However, if your goal is a period-correct hot rod, you probably want a Detroit Ford and not a French Ford.
You’ll pay a price for that too, though. As you have seen, finding a good usable original block is tough, even for a mild street engine. If you’re building performance, you’re going to have to search out the best block you can find. That might involve time and disappointment as blocks are rejected.
Following here is the build of a hot rod Ford for Ray Evernham, one-time NASCAR team owner and most recently a TV personality. The engine is destined for the historic Woody Lee T, raced in the late 1940s and early 1950s; it reached a top speed of 133.136 mph at Bonneville in 1951. Current custodian Evernham plans to race it again. Consequently, Mike went through his stash until he found a near-perfect block. Nevertheless, it still needed align boring, boring, new hardened valve seats, and a judicious amount of porting. In essence, it was blueprinted.
You could, of course, buy a brand-new, fully balanced rotating assembly from Scat. However, this example involved mixing and matching an original Merc crank, Scat rods, Ross forged pistons, and Total Seal rings.
Porting the Block
Reams have been written about porting the flathead, because in factory form it’s a very asthmatic engine. Besides, porting is something that you can kind of tackle yourself. I mean, how hard can it be?
Because of the way the flathead was designed, the two inside exhaust ports thread through the middle of the block and heat it up before they are siamesed into one rather than two exit ports. Meanwhile, the outer two exhaust passages snake around the outer cylinders and make sharp doglegs before exiting the block. It is by no means the best design for a performance engine, but you can improve upon it.
If you’ve never tried porting, you should probably buy a junk block to practice on. It’s not a good idea to experiment on the good block you intend to use because you could make a mistake and end up worse than before you started. The porting process followed here took an experienced machinist about 10 hours to complete.
A professional engine builder such as H&H has well used air-powered tools, but electric drills (corded or cordless) and Dremel tools work fi ne. You need only a couple of cutters and a fl ap wheel, which likely come with a Dremel kit.
It’s easy to see what a gnarly casting the flathead typically is just by looking inside the exhaust port. The passages are oddly shaped, with some right-angled turns, with all sorts of nasty casting flaws. However, most of the casting flaws can be smoothed out.
On another stock block, you can see that the standard exhaust port measures just 13⁄8 inches. Plenty of meat is here to allow opening these up wide.
w opening these up wide.
To begin the porting process, Dykem was brushed onto the exhaust flange. If you don’t have Dykem, permanent marker works well.
Mike holds an exhaust header gasket in position while scribing a line into the Dykem. The block has plenty of material in this region, so you don’t have to worry about grinding away too much.
The grinding process begins with one of the cutting tools. You would expect the block to be hard, but it is surprisingly easy to cut if your tool is sharp and you lean on it.
Getting far into the corner, where there is a lot of rough casting, makes sense. It’s possible if you come at it from an oblique angle.
Try to achieve a smooth trumpet mouth shape that blends into the passageway. This one is not quite finished; it’s not ground out to the line yet, but it’s very close.
The exhaust port can be ground out safely from 13⁄8 inches to 13⁄4 inches. Don’t forget to match this measurement to the inlet on the exhaust manifold.
The block is already coated with Dykem. Now, the intake gasket is positioned on block and the shape of the intake ports in the gasket is transferred to the block with a scriber.
As seen by the scribed line on the lower left port, due to core shift in the casting process, very little block remains on which the gasket can purchase if all the metal is ground away. Be very conscious of this before you start grinding.
It is easy to see that one of the ports (top) has very little extra metal to grind, so you must compromise. Welcome to flathead world.
Between the two cylinder bores, you can just make out the exhaust passage through the three holes. The two ports immediately to either side are siamesed, and the gases exit to the bottom through the exhaust port. The gases also pass in the opposite direction and exit through the small round holes to heat the intake manifold, which, depending on the application and/or intake, can be plugged off.
Looking down through the intakes, you can see the beautiful job of porting. The numbers stamped into the combustion chamber identify each valve; they are lapped in and become port specific.
Porting the Intake Manifold
On Ray’s Navarro 3 x 2 manifold, Dykem was painted around the ports before the gasket was laid down. Bolts are being dropped into the corner holes to align the gasket properly.
With the gasket removed, you can see the lines clearly scribed into the intake. In some areas, there’s quite a bit of material to be removed; less so in other areas.
Let the chips fly (and they will) as you cut into the soft aluminum with a cutting tool. Wear protective goggles and even a facemask to keep detritus out of your eyes, nose, and mouth.
When the Stromberg BIG97s arrived, Mike used the included gasket to see if the top of the intake would also have to be opened up to match the big carbs.
Again, the intake is marked and then the material is cut away very carefully. Be sure that you do not let the tool get away from you and score the manifold. Also, don’t be too aggressive and cut through the port divider. When you are finished, wash the part thoroughly to clean away all the chips.
After the intake ports were opened up, it’s time to machine a hole in the manifold for the road breather tube. Not all intakes have this feature. You should have already decided if you plan to run one or not.
After all the machining, the intake was bolted down. Not all of the intake bolt holes have corresponding holes in the block. It’s up to you whether to drill and tap these holes. The carbs are the new Stromberg BIG97s, and each flows 250 cfm.
Normally, 8BA inlet and exhaust valves are both 1.5 inches in diameter. However, Ray’s engine has 1.6-inch exhaust valves and whopping 1.75-inch inlets. That necessitates larger, hardened valve seats and commensurate work hogging out the block to accommodate them. The process is the same as described previously.
On the right is the stock 1.5-inch valve used for both inlet and exhaust. In the middle is the new 1.6-inch exhaust valve, and to the left the giant 1.75-inch inlet valve, here with a test spring assembly installed.
The stock 1.5-inch valve is to the left. The new 1.75-inch inlet (right) has a reduced stem diameter to improve flow. The exhaust valves do not have a reduced stem because they experience extreme temperatures.
Each of the 16 valves was hand-lapped using a small amount of fine-grade VersaChem metal grinding compound. You don’t need to overdo it with the compound. Use a back-and-forth motion on the stick, and reposition the valve every so often.
The object of the lapping exercise is to get the middle of the valve to match the middle of the seat perfectly. The seat width is approximately 1/16 (.060) inch, shown here by the dull line around the middle of the valve seat.
Honing the block of this high-performance flathead follows essentially the same procedure described previously, but in this case, the tolerances are much tighter. The fi nal bore is 3.3125 inches with the torque plate. Note that although used, the torque plate has already been removed.
A dial gauge was used to check the exact size and roundness of the bore, from top to bottom. This ensures that the bores meet the manufacturer’s specifications for the Ross pistons.
The aim of the honing process is a nice crosshatch finish that performs superbly.
All of the threads were cleaned using a cordless drill and the correct size taps. This stress relieving is important when building a high-performance engine.
After the machining, grinding, and polishing were complete, the block is washed thoroughly in the hot tank and dried off.
The assembly process is much the same as previously described. However, this is a blueprinted race engine. All measurements are exact and double-checked.
The inside of the block was painted with Glyptal red enamel insulating paint, which not only looks good but also promotes the return of oil to the pan.
All of the valve train components, including Isky double racing valve springs, adjustable Isky lifters, and an H&H racing cam, were assembled and accounted for. The cam has a duration of .302 and a lift of .410.
The new cam bearings were inserted very carefully. Mike made sure that the oil feed holes and the hole for the fuel pump pushrod aligned. He gave them a good coating of engine assembly lube before sliding the new H&H high-lift race cam into place.
An inside micrometer is used to measure spring height. This measurement is critical for a high performance engine.
When put into the spring gauge and set at the correct height, the double spring records only 20 pounds; this engine needs something in the region of 120 pounds. Consequently, a number of shims are required.
The valve assemblies were inserted into the block along with the C-clips. Here, the valve spring is compressed so that the locks (valve spring retainers) can be installed. This can be a tricky, two-man operation. With so much spring pressure, you must be careful not to trap a finger. If you have a magnetic stick to position the locks, use it.
You must be careful not to damage the bearing surfaces when the crank is lifted into the block. Original Merc cranks weigh in at 65 pounds, so it might take two people to lift it. Make sure the crank turns freely.
Heavy-duty heat-treated chrome-moly mains studs from ARP were installed using a little thread sealant. These studs have a tensile strength between 180,000 and 210,000 psi. Chrome-moly nuts were also used.
A set of H&H billet steel mains caps were used instead of the stock caps. The billet replacements offer more strength and rigidity.
Check the crank at every stage of the tightening process to make sure that it turns freely. Then, torque the nuts in sequence to the specified 95 pounds.
The Total Seal rings are put into the honed block, and the gap is measured with a feeler gauge. The chart included with the rings indicates that the top and second rings should have a .015-inch end gap. The chart also notes that the gap is tied to application: naturally aspirated, supercharged, and so on.
To increase the gap, the ring is put into this Goodson ring grinder where it is ground and then rechecked. This laborious process takes time and patience.
A diamond file is used to remove any burrs generated by the gaping process. In this image, a dot is visible on the ring just below the file; it indicates the top or uppermost side of the ring.
Instead of the more common lock rings, spiral locks are used to retain the pin because they offer better retention. Spiral locks are little fl at springs that you pull apart and ease into the groove in the piston. However, they are a little more difficult to install and remove.
The three-piece oil ring is installed by gently winding on the three components. The second ring and top ring are installed next, in the same coiling manner. The dot goes uppermost, and the gaps should be 180 degrees apart.
The pistons are installed following the piston installation procedure outlined in Chapter 8. Note that each piston is numbered and that the arrow indicates the direction it was mocked up, so that each piston goes in the correct hole.
The Melling M-15 high-volume pump is identifiable by the tall cap on the upper end of the shaft. Longer gears enable the M-15 to pump 25 percent more oil than the stock pump. However, it is 11⁄4 inches taller than the stock pump, so more pan clearance is necessary. In addition, an original (short) truck oil pickup was required to match the stock truck pan.
The pickup is carefully aligned with the pan rail so that the stepped flange in the pickup sits in the corresponding recess in the pan baffle.
In this case, a baffled oil pan from a truck is used; the baffle helps oil control and keeps the oil in the sump surrounding the pickup. This is not the truck pan with the inspection plate. The corresponding original factory oil pickup must be used in conjunction with this pan.
Ray supplied a pair of original Sharp aluminum heads from the Woody Lee T. They were in remarkably good condition, but they did need some massaging to make them race ready.
This is one of the original Sharp heads fitted to the Woody Lee T as supplied by the car’s owner, Ray Evernham. The heads were in usable condition; this one is cleaned and ready for machining.
A lot of measuring and some minor machine work had been done, but the heads really needed surfacing before the final work was performed.
A micrometer depth gauge is used to measure the depth of the combustion chamber. The measurement helps determine how much material must be removed to get the chambers back to size and to make sure that the valves don’t hit the heads.
Another depth-measuring gauge is used to determine valve lift; it measures the distance between the top of the deck and the face of the valve, which in this case is .410 inch. This measurement determines the necessary depth of the valve pockets. The clearance between the valve and the head needs to be at least .050 inch. Incidentally, the compressed thickness of the head gasket is approximately .055 (.060 uncompressed), and the stock Ford valve lift is .292 inch.
The valve pockets in the head are machined accordingly. You must still do a physical check to ensure against a miscalculation and to make sure that the valves don’t hit the heads.
A small amount of checking or modeling clay is put into the cylinder head at the crown of the combustion chamber and also in the valve pockets.
The heads (including the head gasket) were bolted to the block with just two studs, and the engine turned over. You can just see the valves in the plug holes so you know that the clearances are tight.
After removing the checking clay from the head, each compressed wafer is measured. The clearance between the top of the piston and the roof of the combustion chamber is .063 inch, which is suffi cient and confirms the previous calculations.
Because of the tight tolerances, the spark plugs should not protrude into the combustion chamber. If a plug protrudes too far, you should either find a shorter plug or use copper washers to raise the plug. Every plug must be checked.
Before the heads are finally installed, a dial gauge is used to ascertain TDC, using cylinder number-1 (passenger-side, front).
When number-1 is at TDC, the pointer on the timing cover and the notch on the crank pulley (here marked in orange) will align.
With the piston at TDC and the pointer and notch aligned, insert the distributor so that the rotor points at the number-1 plug wire, which is indicated on some caps. This gives you sufficiently accurate timing to start the engine. The distributor here is the original Mallory dual-point.
The completed engine for Ray Evernham’s Woody Lee T started on H&H’s test stand with the first turn of the key. It is running test-stand headers, not the final headers. Note that, because it is a race engine, it has no generator and, therefore, a shorter belt was needed. In addition, it has no fuel pump; an electric pump will be used instead. If all the calculations are correct, the engine will produce approximately 225 hp.
Written by Greg Kolasa and Posted with Permission of CarTechBooks