Why USA Needed A Big-Block 6-Cylinder 

Combustion engines are just beautiful, saved humanity countless times throughout the ages, in stormy weather, in firetrucks on the go, police cars, rescue vehicles. Kept the streets free of snow, got you home for christmas, summer vacationing in hot weather and much much more.

Back in the day (I was born in 49) we had a low grade of fuel called "Buss Gas" or "Commercial Gasoline". It had an octane rating of maybe 75 under to old rating system. It's why all these big engines had 6~7 compression ratios. With modern fuel they could be run up maybe 8.5 to 1 and probably make 50% more power with that higher CR and some more timing ... With modern diesel trucks with regen, catalytic converters, and exhaust additives - these older gas engines are starting to get some interest again. But parts are hard to come by 🙃

inline 6 is the best engine geometry ever invented. perfect primary and secondary balance.

I had a 1947 Chevy pickup (converted to a 1 ton flatbed), and I pulled a 248 GMC engine from a 1953 military duece-and-a-half, along with a 5 speed O.D. transmission, and installed it in the Chevy. It was all of 105 hp., but 238 ft. lbs. of torque! It was commonly used in a lot of small to medium sized trucks of the era. They maxed out around 3400 rpm. tops, but had massive amounts of torque from 1200 rpm. to the 3400 rpm. maximum, and would pull heavy loads all day with no complaints. However, they were not easy on gas, and I eventually replaced it with a more modern 1979 250 cu. in. 6 cylinder that had 30 more hp. and better fuel mileage!😉

The Jag 6 was 3.8-4.2L, you can get them everywhere for cheap here! Even comes with a broken Jag for free.

I have a 1954 GMC 5 window fire engine with a 503 in.³ it is a beast! Super slow rever, but has tons of torque. It move that beast around fairly easy. Original Engine still runs really smooth .

When my Father started his construction company about 1948, he bought a surplus Army Deuce-and-a-half, six-wheel drive truck. It had a huge, inline, gasoline six, and was probably one of these engines. it was very dependable. I just vaguely remember the scripted GMC on the valve cover. He kept it for well over ten years, maybe a bit longer.

I bought a 2002 Chevy Trailblazer that had a 4.2 L inline six. What a smooth, powerful engine that was, with a really flat torque curve.

USA railroads were first in Dieselisation, starting in 1930. For transcontinental railroading, steam wasn't particularly suitable due to US geography (water was difficult to procure and transport in the desert). For use in navy submarines, diesel was only correct option. However, it's use on highway was an afterthought in North America until 1960s.

We did have a big block six, it was the Ford 300. It’s still used to this day in agriculture, aircraft pullers , Mail trucks and Delivery trucks….

Straight 6's are special! I recently bought a 1992 Cherokee manual with the 4.0 AMC inline 6, and the engine is such a joy to drive! It has a roar, almost like a V8, and is so balanced you never feel like you're logging it. It just pulls smoothly without shudder, or hesitation from under 1.500 rpm in any gear, but I prefer to rev it out a bit, as it sounds magnificent 😁

Wow what a huge block of over 1000 cb inches. Those big 6's held the place in the heavy duty field until diesel came into their own.

I'm still impressed with the GM 305ci Bigblock v6 from the 60s70s80s.

Straight 6 engines are awesome. No need for balance shafts, harmonic balancers, etc. Only problem is they are long...

Neat to see! Hercules built a 936 ci flathead six. The 478 magnum V6 made only 13 ftlb less than the 504 but did so 200 rpm lower (442@1400). However, the V6 was 254 hp vs. 216 and could wind higher. What blows most peoples minds is that the V6, V12, and V8s were oversquare short stroke engines that pull like an electric motor. The 637 V8 was 5.125 bore x 3.86 stroke, a 637 with less stroke than a 454. GMC figured out that stroke doesn't equal torque. Actually, the math comes out the same. Big bore engines have less piston speed, less cylinder and ring wear, better rod ratios, can fit bigger valves, use smaller cams, and have higher rpm potential. I had a 401 magnum V6 (4.875x3.58) that you could pull down so low the electronic tach quit reading the revolutions, and you could count the fan blades going by, I put a 4bbl on it in a pickup and dual valve springs. I shifted it at 5k rpm, once, I missed a power shift, and it hit 6300 rpm and lived! . By comparison, long stroke motors fall on their butts lugging down before oversquare ones trying to bring the next cylinder up on compression. I have owned 27 GMC v6, v8, v12s gas and Diesel, two 602 Continental inline 6, 3 331 Diamond Reos, 2 302 GMCs and a 251 and 230 Dodge flathead 6. And an International RD 450. Great to see a presentation on these little known stump pullers! The big gassers wete lighter (more payload) cheaper, simpler, made way more hp and bottom end torque, wound higher, and required fewer gears in the transmission than early especially turbo Diesels, they still pull down lower because they don't fall out of the turbo. A gas 478 was 254hp/442 ftlbs, a Diesel 478 was 170hp and 342 ft lb 200 rpm higher. About equal to a 305 gas v6. The gas crunch killed them.

How many people can say they used a GMC 503 inline six to haul loads and make money five days a week in 2024? Its me. I did

Here in Brazil we jave GM 250" L6 in cara ,pick up s,from 70',80's and 90's

I bought a '68 Chevy C/10 Stepside in 1973. It was factory equipped with the L25 292 L6. I still run that truck. On its third engine. Currently 406,000 miles on the odometer.

The inline 6 certainly has it's charm. Some of the most sought after BMWs and Jags were inline 6s. Now we see Dodge going back to the layout in their vehicles. What was old is new again!

Love the sound of those big sixes.

I have a Jeep and a Volvo with straight 6 engines, such smooth power delivery. 😊

Great Video I never knew about some of these Engines 1000 ci strait 6 hell yea !

Hard to imagine big gas engines still? Look no further than Ford's 7.3 V8 (Gas) and Chevy's 6.6 V8 (Gas) in pickups, box trucks, delivery vans, buses, and more :) The 7.3 Ford recently replaced their 6.8 V10.

The 302 GMC engine was amazing powerhouse 2 barrel car with a 3 inches off what more could you ask for with a 12-inch clutch, I believe it was only three or four inches longer than the regular GM engine I installed one in my friends flatbed, what a true powerhouse put a nice 3 inches on all you can hear is The Sweet sound that engine purring under load.😊

Great video on really large U.S. domestic Inline 6 cylinder industrial gasoline engines! I was impressed by the 7 main bearings design & gear drive cams! Nice!

Thanks for showing these unique period engines

That would probably explain why most semi trucks these days are big block straight six desiel. I see where they came from. Those big block straight six gassers are insane

I had a 70 C-10 with the I-6 250ci great to work on. So simple

My grandfather had a GMC after the second war, replacing his 1935 FN truck. Strong he always was saying.

I was getting over 200hp out of a 261 blue flame think it was bored 20 over, balanced and was decked, to have 10.5 compresion. Still have the 55 1st 1/2 ton it was in, daily driver with the 383HT GM V8 and 5 speed tremic trans, was very easy swap. :}

Barra, Australia has already done it!!!

I wonder what would come out if such old enormous straight-six gas engines would be build with today's parts and possibilities, including a turbo and such bells and whistles. 😯💪

imagine modernizing one of these with fuel injection, forged internals, a better and/or bigger cam, and a turbo or two hanging off of it. I wonder what kinda power itd make

The super nice 302 cu in "Jimmy" was a great almost drop in switch to most in-line later Chevys. If I recall the block was about 1 1/2 inch longer so in some it required an adjustment in the radiator mounts etc. Bell housing to Chevy all the same. Nice and a great add on to a Chevy and looks almost original. Some speed equipment was available as cast iron headers and dual intake manifolds, cams etc. There were also the very rare 12 port heads made by one or two cos Wayne Horning and another one I believe. The 302 block could not be bored out much over as the walls got thin. Very sweet sound they made with a nice cam.

3:05 I have seen that snow plow in person every year for over a decade, had no idea it was gas powered. Will definitely be taking a closer look next week. If anyone is in Oregon, Antique Powerland is having their Steam Up the next couple weekends, last weekend of July and first weekend of August every year. Well worth a visit.

Have you noticed that most all simi trucks run I6 engines? Very few V8s. Heavy mining & AG equipment too, all I6s. They build 650hp I6s you can get from the factory in your new simi. An I6 can be tweaked to make 800hp for truck pullin. An I6 only uses 75% as many parts as a V8 making the I6 more dependable and economical as it has 2 less cylinders to feed fuel to than a V8. !

Thank you. Good episode. You can beat the sound of those old petrol sixes but … you can certainly beat their fuel economy😁. Cheers from NZ🇳🇿. Good to be a Patron.

I've always been partial to straight sixes, and have owned them most of my driving life. Starting with a '65 Rambler Classic with a 232 six that I started driving on in the early 70's, on up to the '93 Dodge Cumins I stll have today, and several straight six cars in between, They've been the most practical for me.

Imagine taking the GMC big 6, making a light weight crank , rods and Pistons. Made from 4340 and forged aluminum. Bore it out about .100" and destroke it to around 4"-4.37" and cast a 4 valve head for it, possibly aluminum. With stainless o-ring with dead soft copper gasket around .020", thick. And possibly. Make the head a cross flow. And make billet steel main caps. With additional bolts. Or studs, along with head studs. An aluminum intake manifold holding 6 single barrel carburetors. Possibly holley carbs if they can be found. Or 3x 2,bbl 350 holley carbs. In a high rise design with a dtraight shot down to the intake valves. The runners at about 22° angled down to the head. With a large open plenum the carbs sitting side by side. With the throttle blade sitting directly over the port. With all carbs sharing the vacuum signal. The cam getting around .580" lift and 230° @ .050", using a roller follower. Made of titanium and tool steel roller with oilite bushings . Being double bushed, bushed in the roller and in the follower , or use pushrods to operate the 4 valves per cylinder with hemi style rockers. However a over head cam is best. with a shaft mounted roller follower. with thr shaft feeding the oilthe cam also hollow, feeding oil through pin holes in the lobe bottoms. The follower having milled in oil cups to funnel oil into the bushing, or possibly in a trough, so the cam and follower is filed with oil that slowly drains out when shut off. And possibly incorporate twin spark plugs per cylinder. Using a distributor with two cap and rotors. With the ability to set the timing lightly different. Fire one then with in 1°- 2° if crank rotation fire the other. With the mechanical advance operating them both together. Before the split. Cast 1.75" i.d. stainless header split into 3cyl wit dual out with 3.5" collectors , And possibly go fuel injection, build the same basic intake with individual throttle bodies, and port injection two per cylinder a bottom injector at the top of the runner, with a top mount injector at the ports traditional location. Using smaller injectors for a fine mist ,. using 3x 350-400:cfm throttle bodies, or 6x 300cfm units, or possibly a single 102 mm , mount an aluminum flywheel, with a bolt in .250" iron friction surface with about 60,1/4 counter sunk bolts , with a 5-6 speed manual transmission, or(modified) 6L90 auto transmission. With the shorter stroke light weight free flow head capable of around 120 CFM at .150" lift and 500cfm @1.0" getting to 5700 rpm should be simple. And possibly 6k - 6500for a short time, probably drill the block to access each main oil Galle externally, use a crank drive oil pump. Sump in the pan to remote filter and cooler. Lubrication to the crank, then av1/4" or 5/16" line to the head split to go to each end a follower shaft bearing grooved to feed oil to the shaft . The cam the same way the bushing using using brass labyrinth seals to slow the leak. One on each end of both shafts.with the follower shape feeding oil to the valves,. A basically semi dry sump oil system using the sump as the oil tank.. and possibly use a second pump stage to feed piston oil squirter's a 1/2 line from sump, filter screen about 20' x, 3"-4" forming a zigzag picku screen when placed in a 2" tube with 3/4" pickup welded to the end, placed inside the sump , possibly feeding both pump stages , also incorporating a 18 gauge steel windage tray. To separate the crank from the oil. And possibly mount an adater manifold to alow fitment of a 6-71 Detroit diesel blower, with a air to water intercooler inside the manufold the flow path going from 6-4-2-1 to the blower discharge, the topside ofthe blower having a large 90° elbow to adapt a pair of 650 holley carbs, capable of about 1 bar additional atmosphere. This should simulate a engine twice th displacement! 100 hp per cylinder should be nothing. And 450+lbft TQ without boost. And the stars and moon with boost. With long runnrs for a blower manifold to keep the TQ. This makes me want to find on of these engines. Put it into a modified 55 56 chevy 1/2 ton truck, it would be awesome and very different! Sorry for the rambling, havesn awesome day 🎉

70s and 80s GM straight 6s were the 252 and 292 Chev 6s. Which used a LOT of SBC components. GMC also had some 6s but I have no idea of capacity. Ford used the 300 6 for decades. Same bore and stroke to the 400 M V8 I think Chrysler gave up on 6s with the slant 6. 225. Though in Oz we got the hemi 6 with 215 245 and 265 capacity

If you don’t mind diesel, caterpillar still sells the C6, C7, and C9. All have Tier and 4 final compliment models available now

The biggest problem with petrol engines in trucks is there thirst , a 500 cube conte in a 1942 tank transporter drinks about 3 imperial gallons per mile , 500 cube V8 in trucks from the 70s drink about the same and diesel same displacement sip at about 6 MPG .

One of the main reasons inline 6 motors faded in passenger cars is the length of the block. Long hoods reduced space in the passenger cabin and made the vehicle heavier. Too bad because I love the inline 6’s. Most commercial trucks still use this design. It is far easier to service and is naturally balanced.

Put an LTx style aluminum cylinder head on it with EFI & 6 independent TB's, COP ignition, headers and let it eat. Maybe even VVT-L if you're feeling fancy and don't think you have enough possible future failure points.

The Ford 240/300 is like an upgraded GMC 270/302 - produced one year after the 302 went out of production. In most ways similar, but the Ford had 12 ports.

I loved my 2 Dodge pickups with 225 slant 6’s! One was a 1979c the other a 1982. I don’t even like 4 strokes, but these are sweet engines and tan amazing! Good on gas and loaded with torque as well! Sweet exhaust note too! These sounded very close to a 6-71 2 stroke Detroit!

The USA was slow to use diesel fuel in trucks because they taxed gasoline at a low rate, a lot less than on diesel fuel. Thus their tax regime masked the cost saving in using more efficient diesel engines. It should be noted too that the USA is an extremely conservative, change resistant, country. This shows up in many ways, apart from sticking to gasoline:- sticking to 8-track tapes long after the market died elsewhere; 8-bit s-100 CP/M computers selling long after the world changed to 16-bit DOS computers; and refusing to go metric.

Imagine what one of those high cubic inch 6’s would do today with modern EFI and boost. 🐌

I like many types of engines. I admire every type of engine design. But straight inline six engines are my first and forever love, especially long stroke inline sixes. Torque rules over horsepower. Torque can move anything, no matter how gigantic, if you are smart enough not to be in a hurry. Nothing has more torque, and smoother torque, and indestructible simplicity and durability, than a straight six engine. I've never worked on or driven a straight six of more than 300 cubic inch displacement. I'm not sure I've even been near a running straight six of more than 300 cubic inch displacement. I'm a scrapyard wander for 5 decades but not really seen any massive gasoline straight sixes. Id have noticed them and I'd have taken a bow to them. I'd be in awe standing next to one that's running. I'd be very turned on to drive one. And thank you for showing yours in a shop environment where real people are doing real things, not some fake-ly fastidious environment cursted for a camera.

Fun fact. GMC never had a v8 engine. Ever! My old bus came with with a 478 V6. Pretty cool

DO a video on the new Cummins 6.7 GAS straight 6

You had me at inline 6! 😍

Minneapolis Moline used a 504 ci inline 6 gasser in tractors.

If doing real work is just part of your life then the 6 cylinders are your friend. Ford, GM and Chrysler have all made a solid 6.

450 ft/lbs just off idle out of a gas 6 cylinder. Unreal.

GMC did briefly make a 707cid straight six.

I bet the guy in the second video is real bad ass with out that camera in his hand.

Id like to see a modern big block inline 6 aluminum block fuel injection with turbo charging and DOHC 😎

Very interesting! Thanks for presenting this excellent video content!

I have something that looks like this in a 69 Chevy grain truck. You can drive it all week on the farm, but 30miles to the grain elevator and back will burn a full tank of 20!gallons. Top speed floored loaded is about 60 mph. 70 unloaded. Only 30k miles on her.

Thanks again

International Red Diamond 501 Cubic Inches.. Hercules , Hall Scott ..White ect

Its important to recall that in WW2 the US and UK tanks were petrol, so were the heavy military trucks and even the MTBs. The military had all the supply in place for petrol and did not want to change to diesel and they bought a lot of trucks.

It’s crazy that diesels had been around for 40 years without more development.

That’s awesome!!

Cummins has converted their isx15 to operate on natural gas or propane. Theyve recently did a conversion on a 6.7isb to run on gasoline

This is trucks, but I knew 2 locals who raced at the local 1/3 NASCAR oval always with 6 rather than 8. 200 lbs lighter and better handling.

Imagine that 503 with 5 to 7 lbs of boost.

I seriously doubt that GM would have called any displacement in liters back then. They would have all been in cubic inches of displacement. And as they say, there's no replacement for displacement :)

5:04 sounds like a turbo diesel. Is that really a gas I-6, or is this just a visualization of what truck may have had this engine?

I owned a early model GMC wrecker truck that had the 503 engine. It had duel exhaust and a four barrel carburetor. I did run but my brother was impatient and sent it to the crusher. Said no purpose in saving junk trucks and other stuff stored on his property. I really was hurt by his decision to junk it and maybe he was right in the fact that I was broke and could not use it.

You know what they say.. there's no substitution for cubic inches..

Great video as usual

I have a big block 6 cylinder engine. It's a 3.5L with dual overhead cams and EFI. Runs wonderfully in my Lincoln MKX. What country are you from?

(2:30) That head looks to have had a blown head gasket.

Did we need it? That's a good question. We could have used diesel engines instead of petrol, both for greater torque and efficiency. However, back in the old days, farms and industrial sites had their own fuel depots on property, and it was more convenient to use one fuel for all. We had a single axle dump truck with a big petrol inline six. GM also made a big V6, which was also made into a V12.

My dad drove all 48 and Canada before diesel trucks were used born 1917

Gday mate , luv ya work. Do u Kno of the 1938 'Gusabera' V8 2 stroke bike ?

Ford 7.3 godzilla is bringing the big block gasoline engine back.

Time 504 Looks like they left a rear facing door open swinging in the breeze.

The atlas was fairly large at least on the outside. How big should it be?

3 litres, 130 HP and 30L/100 km?😂😂😂

Looking at old engines makes me cry… I work on German cars…. Look up a 4.4l TT V8 from Audi/Lamborghini. You’ll see why I don’t like them.

Diesels of the time were not at all convenient, with long complicated start up proceedures and especially poor cold weather starts.

3:31 Are pairs of intakes sharing one port? I don't recall ever seeing a six-cylinder head having nine ports.

Big 6 hd

Wait till this guy finds out about the continental r6602

Why won't it let me like your video?

1091 Hall-Scott!

Chonk block engines....

The commenters thick accent makes parsing out details difficult .

4.9 ford

These material are used six cylinder engine

Can't understand you.

bigger loads. he’s saying “bigger loads” not “bigallows”. it’s his weird accent.

👀🇮🇪👍⚓

I need $$$😢 t repair my 258 AMC. 4 my jeep😢 i need $$$$

Not a big block I6 A *bigger block* I6

Gg

You talked over the good sounds and shut up over silence. I get it, Europeans hate the awesome sounds of American engines, they’re not as annoying as a fart through a trumpet but they’re musical here in America and tacking over it is just irritating. Why not just mute the engine sounds altogether if you want to talk over it? Not watching the rest and getting nothing out of it.