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

so here at the horsepower monster we are all about bringing you great builds of engines that bring well monstrous levels of horsepower to the table but forged flathead is so important to the hot rodding movement and by today's standards so weird we couldn't resist a chance to do a deep dive on this iconic engine plus this is going to be a great baseline for a future video we're working on with keith thornton an automotive specialist he has a flathead that's going to be competing at bonneville salt flats for a land speed record that is just out of this world he has totally reworked the engine from top to bottom and is going to turn some heads with the innovations he's got going on in there but if you're not familiar with the stock flathead you can't appreciate everything he's done so this video will help you see that make sure you stay tuned for that one too the flat head is nearly a hundred years old now and pretty unique compared to modern engines so on top of being a pretty interesting build this video provides a baseline to compare with for the gonzo build we've got coming up anyhow this is almost a straight up rebuild our friend keith thornton at automotive specialist is doing for a customer who wants a period correct flathead to go into a restored 1938 ford pickup but the guy actually wants to drive his truck and a hundred horsepower lump of iron isn't exactly the best option for modern highways this customer wanted dorton to help him make more power out of the flathead but he didn't want to stray too far away from that stock look plus he wanted to be able to return it to totally stock restoration state if you wanted to later on so no extreme machining to either the block or the heads that means only basic machining to the block and cylinder heads and no matter what it has to stay period correct so dorton cooked up a plan to add stroke to the engine which will also improve compression and also add an old school dual carb setup that should provide enough horsepower to be able to accelerate up to speed so the owner isn't exactly inviting death anytime he tries to merge into traffic on a highway anyway the block is a 239 from 1944 that makes it an early model which means pre-1949 the original engine was worth 100 horsepower and had a stroke of 3.75 inches and a 3.1875 inch bore the terrible gas back then and the design of the combustion chambers meant that the compression ratio was an incredibly low six and change to one we're upping both the cubic inches and the compression ratio with a stroker crank from scat that ups the piston sweep to 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 it helped make the flathead the first v8 that was affordable for the everyday person this scat crank has the same look and feel of the original except for the longer stroke and the raw journals are small black chevy size but before the crank can go into place dorton preps the rear main seal companies have tried to develop a modern molded lip seal for flatheads but they never seem to work dorton says he's seen the best results using a modernized rope seal by a company named i kid you not best gasket the old rope seals were asbestos and when the automotive companies were forced to stop using them they really struggled to come up with a good seal material but this is a graphite impregnated braided teflon which seems to do the trick after pressing the rope into its groove jordan trims the ends to length to get a good seal the cuts have to be perfectly clean with no frayed ends so bess actually includes a fresh razor blade with each seal the other half will go into the main cap another unique feature of the flathead v8 design is it only has three main bearings instead of the usual five this was originally a cost saving measure by ford but it does hurt in terms of strength of the block and support for the crankshaft these are standard babbitt bearings you see installed here which are a big upgrade over the poured babbitt bearings originally used dorton applies plenty of lube to the bearings and then squirts motor oil onto the rope seal the seal absorbs the oil which helps provide enough lubricity between the seal and the metal of the crank to keep the seal from burning up and now we can set in the crank which you can tell by looking at the counterweights is no light weight by any means this bad boy is in the range of 60 pounds jordan drops onto three main caps but notice the unique radius cut ridge or tang machined into the bottom of the main cap these slide in the grooves cut into the block to locate the caps instead of using dowel pins this method works okay for locating the caps laterally but it is possible to spin the calf a bit either clockwise or counterclockwise and bind it up 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 rotates easily after bolting up each cap then once all the caps are in place the nuts on each main stud are tightened to i think it was 85 pounds then dorton rejects crankshaft in play to ensure he still has about five to ten thousandths movement believe it or not up until 1940 the flathead had no provisions for any type of oil filter and even after that it was optional even so on our 1944 block the oil is pumped into a pair of forked galleries where some goes to the engine and about 10 percent or so goes to the filter if you're using one this obviously isn't optimal snorting modifies the oiling passage so that all the oil can first go to a modern canister filter and then be returned to the block under pressure i'll show you the full setup just a little bit later on 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 the top the flathead is unique among modern engines because the valve train is contained in the block the heads are essentially just flat you get 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 they are pretty small and the air and fuel has to follow a pretty convoluted path to get from the carburetor to the combustion chambers so they aren't going to flow very well no matter what you do the valves are seated in the deck of the block and open vertically away from the pistons here you can see on the underside of the cylinder head how the chamber is absolutely huge in order to connect both the valves and the area over the piston to go with the four and a quarter inch stroke of the scat crank the boards have been opened up to 3.3125 inches that will increase the total displacement from 239 cubic inches to 293 which is kind of cool for the piston and rod combo dorton is using a set of eight scat connecting rods matched to molle pistons the rods are 7 inches long from center to center this h-beam design made from 4340 steel is a big upgrade over the stock rod but interestingly because the design of the big end is wider if you're going to use these rods they require a bore of at least three inches 250 thousands the pistons as i've mentioned are from molly they're what allows dorton to squeeze that extra half inch of stroke into a stock block you don't want to shorten the connected rods if you don't have to because that reduces your rod stroke ratio and the longer stroke we already have is going to increase pressure between the pistons and the cylinder wall anyway so we kept the stock 7 inch length and instead used a set of pistons with a short one inch 313 thousandths compression height that's the distance between the center of the wrist pin bore and the top of the piston and it's right at 250 thousandths less than the 1 inch 561 thousandths stock compression height the slipper skirt design also makes the piston lighter and less draggy against the cylinder walls than the original full round pistons plus molly's anti-friction coating on the piston skirts helps reduce piston scuffing in a stroker application like this good stuff all around it's also worth noting that even though there are obviously no valve pockets in these pistons after all the valves are nowhere near them the pistons do have to go into the block a certain way that's because they are machined with offset pin bores here if you look closely you can see how there is less material on the right hand side of the pin boss than on the left after finishing rod and piston assembly dorton installs the rings this is a low tension 1.5 1.5 three millimeter ring package which would have been unfathomable back when the flathead was first designed both the top and second rings are gapped at 20 thousandths of an inch and once the rings are installed in the pistons jordan can start dropping the assemblies in the block [Music] one quirk worth noting is the odd way the flathead numbers its cylinders even though the driver's side bank is forward in the casting it's the first cylinder on the passenger side that's labeled the number one cylinder for setting up timing so the passenger side bank holds 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 rods in you can see the setup with the massive counterweights on the crankshaft next up comes the camshaft this is a solid flat tappet from iski jordan describes it as a pretty mild grind but it is ground on a 114 degree intake center line with 111 degrees of lobe separation duration at fifty thousands tablet lift is 226 degrees for both the intakes and exhaust ischi describes this as a three-quarter race cam with good idle and good low to mid-range power which is just about perfect for this build but before we install the cam first take a moment to check out the big grooves cut into the cam journals this is necessary because of how ford routed the flathead's oil galleries notice the tube running the length of the lifter valley this is essentially the main gallery feeding oil throughout the engine the oil is fed from this tube to the cam journals and then from there it leaves to lubricate the crankshaft's mains not exactly ideal but the large grooves in the cam are there to help move more oil around the cam and to the crank because this is a flat tappet cam dorton applies a liberal coating of thick molle based paste on all the lobes to protect them on first startup then assembly lube is applied to the cam journals before carefully sliding it into the block to spin the camshaft the flathead uses a timing gear instead of a chain driven setup originally the cam gear was made from a fiber material but for our case we'll be going with a timing gear set utilizing a more durable aluminum cam gear note that because the timing setup is gear driven the camshaft actually spins counterclockwise or opposite the direction of the crankshaft you'll also notice a pretty unique setup for degreeing in the camshaft for the flathead you have to be able to reach all the way from the deck of the block through the valve seat and into the lifter valley to contact the lifter it requires a very long reach for your dial indicator to manage this dorton welded a length of rod directly to a tip that screws into his dial indicator making sure the rod stays parallel to the movement of the indicator tip now he can reach into the block to touch the top of the lifter and yes that is a bolt you see there flat heads are full of crazy stuff but more on that in just a moment now we'll flip the engine one more time to work on the bottom again as i mentioned earlier this is an early flathead which ran from the introduction in 1932 until 1948. 49 and later models have significant differences but the easiest way to spot an early flathead is to cast in belt housing at the back of the block the early model flatheads use a specific oil pump which you can still get but dorton says it's almost impossible to find either a repop or a new old stock pickup so he had to fabricate his own by welding together two pickup tubes out of a small block chevy the oil pump gear is driven off the back of the camshaft and the cast gear and cover plate just bolts up like you see here the oil pan and gasket set up on the early flatheads is also you guessed it pretty unique the sheet metal oil pan also forms the lower half of the bell housing that's cast into the block so this piece of sheet metal cut into a half moon you see here actually seals the oil in the sump this piece of cork gets glued into a groove in the main cap and that thin piece of sheet metal in the oil pan cuts into it to seal everything off right now however we're just using the oil pan to hold the strip of cork down until the glue dries we can't actually bolt the oil pan down 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 cast in bell housing so the flywheel which weighs nearly 50 pounds by the way has to go into place and we bolt it up before we can do a final install on the oil pan it's an original unit and has a ton of material making up an outside inertia ring for smoothness of operation but here you can see where the cork strip sits that the oil pan will seal against now dorton can replace the rest of the pan gasket on the block and bolt down the original pan for the final time this pan by the way has the largest drain plug i've ever seen i'm assuming it's because of the terrible oil they had way back in the day and the big plug helped get all the sludge out and with that done we can finally start on the valve train remember when dorton was degreeing in the cam and you could see a hex bolt sticking out of the lifter bore turns out that's legit here's a better look at the solid lifters the flathead uses the bolts sticking out of the top are exactly that except with interference threads so they won't easily turn and they can't back out they're used to set the lash of the valve train hey this is 1930s air technology at its best but it works we'll be installing cast replacement valves back into the block both the intakes and the exhaust are the same size approximately an inch and a half in diameter the valve springs are from iski they have 80 pounds of pressure on the seat and just 200 at full lift the retainers aren't actually stock for a flathead turns out they're a set of used small block chevy retainers that dorton already had on hand and they just cut them down on the lathe and make them work the valves will slide into these valve guides pre-49 flat heads have split valve guides and mushroom tips on the valve stems but we aren't saddling this engine with that stuff the rubber ring helps seal the intakes and the silver clip you see locks the valve guide and spring assembly into the block it's hard to visualize it all going together so hang on and i'll show you the valves and springs actually assemble together before going into the engine dorton starts by adding assembly lube to the valve stems then slides the valve into the guide next the spring and retainer slide over the stem then dorton compresses the spring until he can get the locks into the groove here you can see the completed assembly it's definitely very different from the usual overhead valve setup on more modern engines the valves drop into the block right from the top but first i wanted to point out another issue with the flathead 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 charge takes but the exhaust path is downright crazy those aren't freeze plug holes in the side of the block those are exhaust ports when the exhaust valves open the burnt residue of combustion moves past the valve into the bowl area and then takes a hard turn into a port cast inside the block that's the turn the exhaust has to take to get into the port lighted in the area of this shot the two center valves are both exhausts and combined into one exhaust port you can see the outside of that cast port running vertically inside the water jacket here that's why the flathead v8 has that iconic exhaust manifold with just three tubes having the hot exhaust gases move through the block is also the main reason why flatheads struggle with overheating and cracked blocks it's mostly just something you have to live with anyhow now we can begin assembly 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're dropped into the lifter bores the assembly is dropped into the block but it's a tight fit and requires a bit of work to get it properly seated 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 springs coils and grab hold of the valve guide then he has enough leverage to fully seat the assembly in the box once it's seated the silver c-clip can be inserted into the groove cut into the top of the valve guide and that locks it in place with the block and holds everything in position [Music] the next step is to set the lash on the valve train honestly this process can be a huge pain in the you know what you begin by rotating the cranking cam until the lifter is on the heel of the cam lobe its lowest point so that you can see how much last you've got then you can check the lash between the tip of the valve stem and the bolt on the lifter in our case iski recommends a cold latch of 14 thousandths of an inch the lifters have holes in the top of the body on either side of the adjuster as you can see here to be able to run the adjuster bolt in or out you have to be able to hold the lifter steel so it won't spin which is what the holes are for door makes his own lifter tool to keep it from spinning while he uses a wrench to turn the adjuster remember it's an interference thread cut into the lifter so the bolt has some resistance to 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 sunk too far into the lifter bore so you have to rotate the cam until the lifter is up out of the bore then bend the cam again and drop the lifter back in the bore and check your lash odds are you won't get it right on the first shot so repeat this annoying process again and again until you get it right by the way since there's no rocker arm to increase the leverage the lobe lift which is 364 thousandths of an inch in our case is exactly what you get for the valve lift minus the lash by this point dorton has not only installed the 24 studs used to secure each head to the block he's also painted everything original flathead dark green before bolting up the heads for the final time he does a quick check with some clay to determine he has enough valve to chamber clearance both vertically and laterally everything seems copacetic here so it looks like we're good to go i kind of think it's funny how ford went from complete overkill with 24 head studs on the flathead to a measly 10 fastener securing each head on a windsor anyhow each of the 7 16 head studs gets torqued to 55 pounds once the heads are bolted up jordan whistles a couple of chambers to verify the compression ratio we came up with a compression ratio of 8.4 to 1. hey not great but there's only so much you can do with these original heads still it's better than the six and a half or so the engine originally had one concession we did make to modern dependability over originality is a modern distributor this replaces the old integrated distributor coil and condenser which looks quite different still this model like the original unit is driven directly off the nose of the camshaft the intake is an offenhauser repop with provisions for double deuces and those deuces mixing the air and fuel are primary 9 super 7 carbs that are based on the old stromberg super 97 model these are all new carburetors and cast from aluminum and not cast iron like the old strongbergs though finally dorton fits up the alternator that's 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 tension on the belt and here's the engine complete on the dyno now you can see the belt i was talking about i love the old-school clear red fuel lines they attach to a manifold distribution block it's just left hanging here on the dyno but in the car this will mount somewhere on the firewall there's also an old-school fuel pump at the back of the block complete with a very cool glass fuel filter and now that everything is plumbed up on the dyno you can see a little better where i spoke about earlier on the oiling system modifications all of the pressurized oil from the oil pump now goes out of the block through a remote mount oil filter with a modern canister paper filter and is returned to the block on the top of the boss anyhow let's fire this old girl up and hear her run [Music] after a complete break-in for the flat-tap of lifters and cam jordan checked over the engine gave the okay and we are ready to make some power pulls so [Music] [Music] generally speaking the flathead is not a rev happy machine so dorton limited the pulse to 4400 rpm if you're used to modern race engines it feels weird to pull back on the handle when the engine sounds like it's just getting started anyhow power isn't exactly over the moon but the torque curve is as flat as a pool table we saw a torque peak of 242 and a half foot pounds at 3 300 rpm and a maximum horsepower of 170.1 at 4300 rpm still that is a ton better than the 100 horsepower this engine originally made and nothing has been done that keeps it from being returned to purely stock form but now we've got an engine that keeps his old school looks while being dead reliable and has enough power to accelerate to 65 or 70 miles an hour to safely merge with traffic and cruise there all day long but we're not done yet the carbs came with these very small air filters they're barely larger than a breather you'd stick on a valve cover on a traditional small block so we thought we'd test them too for comparison just so you can see here's a stock breather for the flathead it's not exactly what anyone would call sexy but you can see just how much larger it is than what we're working with here anyhow here's a pull with a tiny air cleaners attached [Music] [Music] we thought those small air cleaners would hurt power but we had no idea it would be this bad power was down throughout the pull and it only got worse the more rpms increased peak power was down 17 horsepower to 153.1 at 4 000 rpm so obviously dorton will work with the owner to find an air cleaner option that keeps the old school look while flowing a whole lot better than these duds anyhow thanks for watching if you enjoyed this video please check out these cool engine builds too and if you have any stories about messing with flatheads please tell us about them in the comments hey like and subscribe if you haven't already and we'll see you next time [Music] you

Channel: The Horsepower Monster

Views: 309,921

Rating: 4.9351621 out of 5

Keywords: Ford Flathead V8, how to build a ford flathead, ford flat head engine, famous engines, scat flathead stroker crank, scat flathead connecting rods, mahle flathead pistons, isky flathead camshaft, isky flathead lifters, flathead cylinder heads, how much horsepower did a flathead make, automotive specialists, keith dorton, jeff huneycutt, horsepower monster

Id: sUvM5te8ZoY

Length: 27min 38sec (1658 seconds)

Published: Sat Feb 20 2021