All the Oddities of Ford's Famous Flathead V8 (Full Engine Build)

So here at Horsepower Monster our goal is to bring you great

engine

build

s that bring monstrous levels of horsepower to the table, but the forged

flathead

is very important to the hot rodding movement and by today's standards it is so rare that We couldn't resist the opportunity. to do a deep dive into this iconic

engine

and will also be a great basis for a future video we are working on with Keith Thornton, an automotive specialist. He has a

flathead

that will compete on the Bonneville Salt Flats for land speed. He records that he is out of this world, he has totally redesigned the motor from top to bottom and is going to turn heads with the innovations he has there, but if you are not familiar with the original flathead, you won't be able to appreciate it. everything he's done, so this video will help you see that, make sure you keep an eye out for that too.

The flathead is almost a hundred years old now and is quite unique compared to modern engines, so in addition to being a pretty interesting

build

, this video provides a baseline to compare to the gonzo build ahead of us all. Anyway, this is an almost straight rebuild that our friend Keith Thornton at Automotive Specialist is doing for a customer who wants a period-correct flathead for a restored 1938 Ford truck, but the guy really wants to drive his truck and a hundred-horsepower hunk of iron isn't exactly the best option for modern roads. This customer wanted Dorton to help him make more power with the Flathead, but he didn't want to stray too far. that original look and I also wanted to be able to return it to a

full

y restored state if I wanted to later, so there is no extreme machining on either the block or the heads, which means just basic machining on the block and heads and no matter what it is.

It has to be kept in the right spot, so Dorton came up with a plan to add stroke to the engine, which will also improve compression and also add an old-school dual-carburetor setup that should provide enough power to be able to accelerate up to speed. suitable for the owner not exactly inviting death every time he tries to merge into traffic on a highway anyway, the block is a 1944 239, making it an early model, meaning that before 1949 the Original engine was rated at 100 horsepower and had a 3.75-inch stroke and 3.1875-inch stroke. It had terrible gas back then and the design of the combustion chambers meant the compression ratio was an incredibly low six and by switching to one we are increasing both cubic inches and compression ratio with a Scat crank that increases the piston sweep.

At four and a quarter inches, interestingly, Ford was the first to develop a cast crank that was strong enough to last in a V8 engine and helped make the flathead the first V8 af

ford

able for the average person. This scat crank has the same look and feel of the original except for the longer travel and the blank journals, they are small in size and black, but before the crank can be put into place, Dorton Preps, the Rear main seals have tried to develop a modern molded lip seal for flatheads, but they never seem to work. Dorton says he has seen the best results using a modernized rope seal by a company called i kid you not best packing.

The old rope seals were asbestos and when car companies were forced to stop using them, they really had a hard time finding a good sealing material. but this is a graphite-impregnated braided Teflon that seems to work after you press the string into its slot. Jordan trims the ends to size for a good seal. The cuts must be perfectly clean and free of frayed ends, which is why Bess includes a new razor. sheet with each stamp, the other half will go to the main cover. Another unique feature of the v8 flathead design is that it only has three main bearings instead of the usual five.

This was originally a cost-saving measure by Ford, but it hurts in terms of endurance. of the block and bracket for the crankshaft, these are standard Babbitt bearings you see installed here, which are a big improvement over the poured Babbitt bearings that were originally used. Dorton applies a lot of lubricant to the bearings and then sprays engine oil on the winding seal, the seal absorbs the oil which helps provide enough lubricity between the seal and the crank metal to prevent the seal from burning and now we can attach the crank, which you can see by looking at the counterweights it is not light by any means, this bad boy is in the 60 pound range, Jordan falls on three main caps, but notice the machined single radius cutting ridge or tang at the bottom of the main cover.

These slide into slots cut into the block to locate the caps instead of using pins, this method works. It is okay to position the caps laterally, but it is possible to turn the calf a little clockwise or counterclockwise and attach it against the crank journal. It's not a big deal as long as you're aware of it, you just have to make sure the crank still turns easily after you screw each cap on, then once all the caps are in place the nuts on each main bolt snap together. They tighten it to, I think, it was 85 pounds, then Dorton rejects the crankshaft in play to make sure it still has five to ten thousandths of movement, believe it. or not until 1940 the flat head had no provision for any type of oil filter and even after that it was optional, still in our 1944 block the oil is pumped into a pair of branching galleries where some goes to the engine and About 10 percent or so goes to the filter, if you are using one, this is obviously not optimal.

Inhalation modifies the lubrication passage so that all the oil can go first to a modern canister filter and then return to the block under pressure. I'll show you the

full

setup a little later in the build, but now with the crank in place we can turn our attention to the rest of the block. Here's a view from above. The flat head is unique among modern engines because the valve train is contained in the block the heads are essentially flat you make it right plates used to provide a top for the combustion chambers the holes you see in the top of the block are The intake ports are quite small and the air and fuel have to follow a pretty complicated path to get from the carburetor to the combustion chambers, so they won't flow very well no matter what you do, the valves are located on the block deck and open vertically away from the pistons.

Here you can see on the underside of the cylinder head how the chamber is absolutely huge to connect both the valves and the area above the piston to go with the four and a quarter inch stroke of the scat crank, the tables have been opened up to 3.3125 inches, which will increase the total displacement from 239 cubic inches to 293, which is great for the piston and rod combination. Dorton is using a set of eight scat connecting rods paired with molle pistons. Rods measure 7 inches long from center to center. This H-beam design is made from 4340. The steel is a big improvement over the original rod, but interestingly, because the connecting rod design is wider, if you are going to use these rods, they require an inner diameter of at least three inches. 250 thousand.

The pistons, as I mentioned, are from Molly. They're what allows Dorton to squeeze that extra half-inch of stroke out of a stock block. You don't want to shorten the connecting rods if you don't have to because that reduces the rod stroke ratio and the longer stroke we already have is We're going to increase the pressure between the pistons and the cylinder wall anyway, so we kept the stock length of 7 inches and instead we used a set of pistons with a short compression height of one inch and 313 thousandths, which is the distance between the center of the wrist pin hole and the top. of the piston and is just 250 thousandths less than the original compression height of 1 inch and 561 thousandths.

The sliding skirt design also makes the piston lighter and less resistant against the cylinder walls than the stock round pistons, in addition to Molly's anti-friction coating on the piston. The skirts help reduce piston wear in a racing application like this. It is also worth noting that although there are obviously no valve pockets in these pistons, after all the valves are not close to them, the pistons have to enter the block for a certain time. This is because they are machined with offset pin holes here. If you look closely, you can see how there is less material on the right side of the pin boss than on the left after the rod and piston assembly is finished.

Dorton installs the rings. This is a low level. tension 1.5 1.5 three millimeter ring pack which would have been unfathomable when the flat head was first designed, both the top and second rings are 20 mils apart and once the rings are installed in pistons, Jordan may start dropping the assemblies into the One quirk of the block worth noting is the strange way the flathead numbers its cylinders, although the driver's side bank is forward in the casting, it is the first cylinder on the passenger side which is labeled cylinder number one to set the timing so the passenger side bench holds the cylinders. one through four, while the driver's side is five through eight, you don't want to mix that up, so with all the pistons and connecting rods you can see the setup with the huge counterweights on the crankshaft, then comes the camshaft, this It is a solid plane.

Iski Jordan's tappet describes it as a fairly smooth grind, but it is milled on a 114-degree intake centerline with 111 degrees of lobe separation. The elevation duration of the tablet at fifty thousand is 226 degrees for both intakes and exhaust. Ischi describes this as a three-quarter stroke cam with good idle and good low to mid range power, which is almost perfect for this build, but before installing the cam, first take a moment to check the large grooves. cut into the cam journals, this is necessary because of how Ford routes the flat head oil galleries note the tube that runs along the lifter valley, this is essentially the main gallery that feeds oil to the entire engine , the oil is fed from this tube to the cam journals and then comes out from there to lubricate the crankshaft main pipes, not exactly Ideal, but the large grooves in the cam are there to help move more oil around the cam and towards the crank because it is a cam with a flat tappet.

Dorton applies a liberal coat of thick molle-based paste to all lobes to protect them at first start and afterwards. Assembly lubricant is applied to the cam journals before carefully sliding it into the block to rotate the camshaft. The flathead uses a timing gear instead of a chain-driven setup. Originally the cam gear was made of a fiber material, but for our case we will move on. With a timing gear set that uses a more durable aluminum cam gear, keep in mind that because the timing setup is gear driven, the camshaft actually rotates counterclockwise or in the opposite direction of the crankshaft, you will also notice a rather unique configuration for timing the camshaft for the flathead model.

It must be able to reach from the block deck through the valve seat and into the lifter valley to contact the lifter. A very long reach is required for your dial indicator to handle this dorton welded with a piece of rod directly to a tip that screws into your dial indicator making sure the rod remains parallel to the movement of the indicator tip. Now you can reach up to the block to touch the top of the lifter and yes, that is a bolt. You see, flat heads are full of madness. things, but more on that in a moment, we'll turn the engine over once more to work on the bottom again, as I mentioned earlier, this is one of the first flathead models that ran from its introduction in 1932 until 1948.

The models 49 and later have important differences, but the easiest way to detect an early flathead is to cast the belt housing to the back of the block. Early model flatheads use a specific oil pump that can still be found, but Dorton says it's nearly impossible to find a repop or anew. original old truck so he had to make his own by welding two pickup tubes from a small block chevy, the oil pump gear is driven from the back of the camshaft and the cast gear and cover plate They are simply screwed on as seen here the oil.

The crankcase and gasket installed on the early Flatheads is also, you guessed it, quite unique. The sheet metal oil pan also forms the lower half of the bellhousing which is cast into the block, so this half-moon cut sheet metal piece is actually seen here. It seals the oil in the crankcase, this piece of cork sticks into a slot in the main cap and that thin piece of sheet metal on the oil pan cuts it to seal everything at the moment, however we are only using the crankcase of oil to hold. the cork strip down until the glue dries, we can't actually bolt on the oil pan yet because believe it or not, you have to install the flywheel before the oil pan because there is no other way to get it inside the mold in the bell.

So the flywheel, which by the way weighs almost 50 pounds, has to be put in place and bolted on before we can do a final installation on the oil pan. It is an original unit and has a ton of material that forms an outer inertia ring for added smoothness. of operation, but here you can see where the cork strip sits against which the oil pan will seal. Now Dorton can replace the rest of the crankcase gasket in the block and bolt the original crankcase on one last time. By the way, this crankcase has the largest one. drain plug I've ever seen, I guess it's because of the terrible oil they had in the past and the big plug helped get all the sludge out and once that's done we can finally start on the valvetrain, remember when Dorton was?

When you graduated on the cam and you could see a hex bolt sticking out of the lifter hole, it turns out it's legit. Here's a better look at the solid risers the flathead uses. The bolts sticking out of the top are exactly that, except with interfering threads, so no. They do not turn easily and cannot reverse. They are used to adjust the valve train clearance. Hey, this is 1930s air technology at its finest, but it works. We will install cast replacement valves into the block, both the intakes and valves. the exhaust is the same size about an inch and a half in diameter the valve springs are from iski they have 80 lbs depression at the seat and only 200 with full lift the retainers are actually not stock for a flat head.

Turns out they are a set of used small block Chevy retainers that Dorton already had on hand and they just cut them on the lathe and made them. They work, the valves will slide inside these valve guides, pre-49 flatheads have split valve guides and mushroom tips on the valve stems, but we're not going to saddle this engine with that stuff, the rubber ring It helps seal the sockets and the silver clip, you see. locks the valve guide and spring assembly into the block, it's hard to visualize everything going together, so hold on and I'll show you how the valves and springs are assembled before going into the engine.

Dorton starts by adding assembly lubricant to the valve stems and then slides the valve into the guide, then the spring and retainer slide over the stem, then Dorton compresses the spring until it can fit the locks into the slot. Here you can see the complete assembly. It's definitely very different from the usual overhead valve configuration on more modern engines. The valves drop into the block from the top, but first I wanted to point out another issue with the flat head. I've already shown the intake ports on the top of the block and it's pretty easy to visualize the path of the incoming air and fuel. charging is needed, but the escape route is completely crazy.

Those are not freeze plug holes in the side of the block. Those are exhaust ports. When the exhaust valves open, the burned residue from combustion passes through the valve into the bowl area and then takes a sharp turn. on a cast port inside the block, that is the turn the exhaust must take to enter the port illuminated in the area of ​​this intake, the two center valves are exhausts and combined into one exhaust port, you can see the outside of that cast port working. vertically into the water jacket here, that's why the flathead v8 has that iconic exhaust manifold with only three pipes, making the hot exhaust gases move through the block and it's also the main reason why the flathead fight against overheating and cracked blocks;

It's mostly something you have to live with. Anyway, now we can start assembling. Dorton has already coated the cam loads with a thick molle-based paste, but more is added to the face of the flat tappet cam lifters before they drop into the lifter holes, the assembly is dropped into the block, but it is a perfect fit and requires a little work to seat correctly. Here's a tool you don't normally see in an engine shop, but this giant pry bar is made specifically to fit between the valve spring coils and grab the valve guide. You then have enough leverage to fully seat the assembly in the box.

Once seated, the silver C-clip can be inserted into the slot cut into the top of the valve guide and that locks it in place with the block and holds everything in position. The next step is to place the whip on the valve train. Honestly this process can be a big pain, you know what you start by turning the crank cam until the lifter is at the heel of the cam lobe at its lowest point so you can see. how much last you have, then you can check the play between the tip of the valve stem and the bolt on the lifter.

In our case, Iski recommends a 14 mil cold latch. The risers have holes in the upper part of the body. on each side of the adjuster, as you can see here, in order to move the adjuster bolt in or out, you have to be able to hold the steel lifter from rotating, which is what the holes are for for the door to make its own elevator. tool to prevent it from turning while using a wrench to turn the adjuster, remember it is an interference thread cut into the riser, so the bolt has some resistance when turning. Also, you can't reach the bolt holes in the lifter body with the lifter on the heel of the cam lobe because it went too deep into the lifter hole, so you have to turn the cam until the lifter comes out of the hole. , then bend the cam again and drop the lifter back into the hole and check its lash odds.

You won't get it right on the first shot, so repeat this annoying process over and over until you get it right, by the way, since there is no rocker arm to increase the leverage, the lobe lift, which is 364 thousandths of inch in our case, it's exactly what you get for valve lift minus lash At this point, Dorton not only installed the 24 bolts used to secure each head to the block, but he also painted the entire original flathead green dark before screwing the heads on for the last time, and does a quick check with some clay to determine that you have enough clearance between the valve and the chamber both vertically and laterally, everything looks copacetic here, so it looks like we're ready to go .

I think it's funny how Ford went from total overkill with 24 flat head bolts. to a measly 10 fastener that secures each head on a Windsor anyway, each of the 7 bolts on the 16 head are torqued to 55 pounds once the heads are bolted on Jordan whistles a couple of cams to check the ratio of compression, we got a compression ratio of 8.4 to 1. Hey, it's not great, but there's a lot you can do with these stock heads, it's still better than the six and a half or so. The engine originally had a concession we made to modern reliability over originality.

It is a modern distributor replacing the old integrated distributor coil and condenser which still looks quite different, this model, like the original unit, is driven directly from the tip of the camshaft, the intake is an offenhauser repop with provisions for double deuces and those twos that mix the air and fuel are primary 9 super 7 Carburetors that are based on the old Stromberg Super 97 model. These are all new carburetors and are made of aluminum and not cast iron like the old Strongberg ones, although eventually Dorton install the alternator which is designed to mimic the look of an old generator so the alternator mounts to the intake manifold on a sliding bracket that allows it to be raised or lowered so you can adjust the belt tension and here is the engine complete on the test bench.

Now you can see the strap he was talking about. I love the old school light red. The fuel lines connect to a manifold block and are simply left hanging here on the dyno, but on the car this will be mounted somewhere on the firewall. There's also an old-school fuel pump at the rear of the block complete with a very cool glass fuel filter. and now that everything is connected to the dyno, you can see a little better than what I talked about before about the lubrication system modifications, all the pressurized oil from the oil pump now leaves the block through an oil filter Remote mount with a modern oil filter. canister paper filter and goes back to the block on top of the boss anyway let's fire this old girl up and hear her run after a full break-in for the flat touch of the lifters and the cam Jordan checked the engine gave the thumbs up well and We're ready to make some power pulls, so generally speaking the flathead is not a high revving machine, so Dorton limited the pulse to 4400 rpm.

If you're used to modern racing engines, it feels strange to pull the handle back when the engine sounds. Anyway, it's just getting started, the power isn't exactly spectacular, but the torque curve is as flat as a pool table. We saw peak torque of 242 and a half pound-feet at 3,300 rpm and peak power of 170.1 at 4,300 rpm. That's a lot better than the 100 horsepower this engine originally had and nothing has been done to prevent it from returning to its purely stock form, but now we have an engine that maintains its old school appearance and at the same time is completely reliable and has enough power. accelerate to 65 or 70 miles per hour to safely merge into traffic and cruise there all day, but we're not done yet.

The carbs come with these very small air filters. They're barely larger than a breather you'd put on a valve cover on a traditional small block, so we thought we'd test them out as well for comparison, just so you can see. Here is an original breather for the flat head. It's not exactly what anyone would call sexy, but you can see how much bigger it is. We're working here anyway. Here is a pull with small air filters attached. We thought those little air filters would hurt the power, but we had no idea that it would be this bad power that dropped throughout the pull and only got worse as the revs increased. peak power was reduced by 17 horsepower to 153.1 at 4000 rpm, so obviously Dorton will work with the owner to find an air filter option that maintains the old school look and flows much better than these rags anyway, thanks for watching if you enjoyed this video.

Please also check out these great engine builds, and if you have any stories about playing Flatheads, tell us in the comments. Hey, like and subscribe if you haven't already and I'll see you next time.