Flathead Engines vs. Overhead Valves

[Guest BJM]

I am in the process of restocking my shelves. I have one car in the garage, a 1973 Buick with a 455 OHV engine. That makes sense. By 1973 there were NO flathead engines left in the mainstream auto industry.

I like the cars of 1946-49 so the cars coming in are a 1949 Kaiser (6 cyl flathead Continental), a 49 Chrysler New Yorker (8 cyl flathead), a 1948 Packard 356 Custom 8 (8 cyl Flathead), a 1947 Chrysler New Yorker (8 cyl flathead) and the oddball is a 1936 Buick (8 cyl OHV).

Packard and Kaiser held out with flatheads until 1954-55. But why? Chrysler went in 1951. Buicks were always OHV. Cadillac in 1949 went to OHV.

Why? Why would automakers not embrace the additional flexibility that OHV technology offered. Why was the flathead engine design favored in the 1st place?

Both of the "luxury" manufacturers in 1948 still used flatheads. Yet both Packard and Cadillac had some of the best engineering staffs ever. And Chrysler was run by engineers for years. By 1955 I would guess, flatheads were all but extinct dinosaurs. So why flatheads for so long?

[1937hd45]

Less parts cause cheaper cars to be built.

[ply33]

Until you get to about 8:1 compression ratio the flathead can be competitive with OHV. Above that it is hard to design the engine for good flow so your volumetric efficiency is less. As long as the gas is too low in octane rating to allow high compression engines then the L-head engine can be competitive. And as 1947hd45 points out, it is a cheaper engine to make.

[CarlLaFong]

Kaiser had flatheads until the end. They toyed with buying Olds engines, but went belly up before it could happen. Packard was in trouble when they brought out their OHV V8. The Ultramatic had to have put a serious dent in their bank account and designing and building a new engine must have really set them back a bundle. Look at who stuck with the old technology. The independents. The Big 3 had a much larger war chest and could afford radical changes. Of course, little Stude beat Ford and Chev with a new OHV V8

[Dave Mellor NJ]

Both of the "luxury" manufacturers in 1948 still used flatheads. Yet both Packard and Cadillac had some of the best engineering staffs ever. And Chrysler was run by engineers for years. By 1955 I would guess, flatheads were all but extinct dinosaurs. So why flatheads for so long?

Also Lincoln and Imperial

[Bleach]

Dodge and Plymouth offered a flathead 6 until 1959 and Rambler/AMC until 1965.

[Guest Sgt423]

I don't know about manufacturers other than Ford, but Ford stuck with the Flathead because it was cheap, could be replaced easily and could be beefed up to do a rugged job. Almost anyone could work on them. As far as Ford went I never understood why Henry put adjustable valves in his 4 cylinder flathead motors and not in the 6 or V8's. I discovered that the valves and lifters in the 9N Ford tractor engine were the same size as the V8 so when I rebuilt my current Flatty I bought two sets and installed them instead. I learned from an old tractor guy up in Pilot Mountain, NC that if you drilled a 1/8th inch hole in the lifter you could adjust the valve much easier by inserting a welding rod end into the hole to hold it steady while adjusting it to the proper setting. That worked like a charm.

Henry wasn't much into change, his opinion was simple if it ain't broke don't fix it. Of course that philosophy damn near ruined the company. The Shoebox Ford (40 - 51) saved the company from bankruptcy. The body style changes along with the suspension system made the difference. Ford made the Flathead engine up until 1954. The French continued making and installing the Ford Flathead V8 up into the late 1990's for their military equipment vehicles.

[Rusty_OToole]

Before 1920 there a lot of different head designs, like the T head and F head as well as OHV and flathead. Flatheads offered simplicity, silence, reliability, low cost and ease of repair. If a valve spring broke which they often did in those days, the engine would continue to run and no engine damage resulted.

But OHV engines could develop a little more power.

Then in 1921 or 22 Harry Ricardo of England invented the Ricardo cylinder head. It brought the top of the flathead combustion chamber down tight to the piston. This had 3 advantages: It effectively reduced the size of the combustion chamber by half, it increased compression, and it caused a squish effect, squirting or swirling the combustion gasses.

The overall result was higher compression, quicker more efficient combustion, and knock or ping was greatly reduced or eliminated.

With the new head design the OHV engine became obsolete.

No new OHV engines were designed after the Ricardo head came out. The only exceptions were from firms that had nailed their colors to the mast so to speak, like Nash, Buick and Chevrolet, and those that built super performance cars with overhead cam engines like Stutz or Duesenberg. In their case the OHC engine did give a small advantage in horsepower but at a cost that only the most expensive vehicles could justify.

The superiority of the flathead engine continued until very high octane leaded gas became available in the early fifties. Some car companies began designing OHV short stroke engines in anticipation in the late forties.

The new OHV engines were rather different. The large bore made room for larger valves than the old long stroke OHV designs. This took away one of the advantages of the flathead. Their valve sizes were not limited by the size of the cylinder, like an OHV. If you look at a flathead valve chamber or head gasket you will see that the valve chamber was wider than the cylinder bore, this was not possible in an OHV engine.

Even then the difference in power was small. Compare the brand new, 1949 Lincoln, 337 cu in 154HP flathead engine to the equally new, 1949 Cadillac OHV engine of 160HP. This was at a time when 7.5:1 compression was the norm.

7.5:1 or 7.8:1 was about the highest practical compression ratio for a typical flathead. Anything higher and the small combustion chamber cuts off the breathing.

Packard achieved an 8.7:1 ratio in 1954 but this was an exception. The Packard featured valves tipped towards the cylinder bores, and quite a sophisticated combustion chamber design.

The short stroke OHV engine was also better suited to high speed superhighways then being built and worked well with automatic transmissions, then becoming popular.

The proponents of OHV engines did such a good job of advertising and promoting them, that the public became convinced any car with a flathead engine was obsolete, totally inferior and soon to be extinct. This was something of an exaggeration but it did kill the sales of any flathead powered car.

Even today owners of cars from the forties and early fifties, are pleasantly surprised at how well their flathead powered cars perform. They may not develop as much horsepower at high speeds as their OHV V8 counterparts but do have plenty of power for all practical purposes and can easily keep up with normal traffic. And the old long stroke, flathead engine with its high torque at low RPMs makes driving a manual transmission car so easy.

Edited August 24, 2011 by Rusty_OToole (see edit history)

[Rusty_OToole]

As to why Packard stuck with the flathead for so long. Many experts felt the flathead had a lot to offer. As I mentioned earlier, Lincoln brought out an all new flathead V8 in 1949. Packard and Hudson both featured new flathead inline engines when others were going to OHV. The Packard was one of the most powerful cars of its time and only a few OHV V8s could out perform it. The Hudson was a stock car racing champion in the early fifties and handily beat all OHV competitors on the race track.

Packard engineering was also busy in the late forties and early fifties with other things. They designed the only automatic transmission by an independent, the Ultramatic, introduced in 1949. An all new body in 1951. Power brakes, power steering, air conditioning and other power accessories were de rigeur for a luxury car. For whatever reason they decided to stick with the flathead straight eight they had pioneered in the early 20s, in a modernised form.

At some point they changed their mind and began developing their own OHV V8. This debuted in 1955, the same year Pontiac, Chevrolet, and Plymouth introduced theirs. So they were hardly the last to market but they might as well have been, as their competitors had brought out theirs 3 to 6 years earlier.

There was also the fact that Packard pursued a very conservative design philosophy in the late forties and early fifties. They went after the steady, conservative buyer in the upper middle and high price brackets. This was not a bad marketing strategy. Rambler did very well with similar strategy in the lower price market. Packard was offering buyers a genuine choice. At the time, Cadillac and Buick were building gaudy circus wagons more suited to Hollywood and Broadway than middle America. Packard was willing to concede Hollywood and Broadway if they could have the rest of the country.

In the end, it turned out America wanted gaudy circus wagons with big tailfins mouth organ grilles and 3 tone paint jobs. But by the time they figured this out (1955-56) it was too late.

By the way in my small town, the rich people would not be seen dead in a Cadillac. They drove Chrysler New Yorkers and Buicks. A successful realtor told me in all seriousness that if he bought a Cadillac it would hurt his business. He had just bought a new 1975 Buick Electra that cost as much as a Cadillac.

I have heard similar stories from the southern US, from New England and from California. Cadillac owners were thought of as too slick, too brash, or making too much profit.To the old money people a Cadillac owner was a character from the wrong side of the tracks who hit it lucky.

In those areas Packard should have done well. But in the fifties, the Brooks Brothers cut was out of fashion.

Edited August 24, 2011 by Rusty_OToole (see edit history)

[Guest]

As to why Packard stuck with the flathead for so long. Many experts felt the flathead had a lot to offer. As I mentioned earlier, Lincoln brought out an all new flathead V8 in 1949. Packard and Hudson both featured new flathead inline engines when others were going to OHV. The Packard was one of the most powerful cars of its time and only a few OHV V8s could out perform it. The Hudson was a stock car racing champion in the early fifties and handily beat all OHV competitors on the race track.

Packard engineering was also busy in the late forties and early fifties with other things. They designed the only automatic transmission by an independent, the Ultramatic, introduced in 1949. An all new body in 1951. Power brakes, power steering, air conditioning and other power accessories were de rigeur for a luxury car. For whatever reason they decided to stick with the flathead straight eight they had pioneered in the early 20s, in a modernised form.

At some point they changed their mind and began developing their own OHV V8. This debuted in 1955, the same year Pontiac, Chevrolet, and Plymouth introduced theirs. So they were hardly the last to market but they might as well have been, as their competitors had brought out theirs 3 to 6 years earlier.

There was also the fact that Packard pursued a very conservative design philosophy in the late forties and early fifties. They went after the steady, conservative buyer in the upper middle and high price brackets. This was not a bad marketing strategy. Rambler did very well with similar strategy in the lower price market. Packard was offering buyers a genuine choice. At the time, Cadillac and Buick were building gaudy circus wagons more suited to Hollywood and Broadway than middle America. Packard was willing to concede Hollywood and Broadway if they could have the rest of the country.

In the end, it turned out America wanted gaudy circus wagons with big tailfins mouth organ grilles and 3 tone paint jobs. But by the time they figured this out (1955-56) it was too late.

By the way in my small town, the rich people would not be seen dead in a Cadillac. They drove Chrysler New Yorkers and Buicks. A successful realtor told me in all seriousness that if he bought a Cadillac it would hurt his business. He had just bought a new 1975 Buick Electra that cost as much as a Cadillac.

I have heard similar stories from the southern US, from New England and from California. Cadillac owners were thought of as too slick, too brash, or making too much profit. Among the old money people a Cadillac owner was a character from the wrong side of the tracks who hit it lucky.

In those areas Packard should have done well. But in the fifties, the Brooks Brothers cut was out of fashion.

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The Hudson Hornet was not as fast as the Olds/Chrysler/Cadillac. The Hudsons advantage in stock car racing was it was faster in the turns because the body was channeled down between the frame rails giving it a low center of gravity. Something Hudson learned from the Hot Rod explosion right after the war.

Growing up in Southern California I never heard that perception analogy about Cadillac. In GM's structure the Cadillac was something for someone to aspire to. Start out with chevy and move up the ranks. Back then all GM cars were made to look like they somewhat had some kinship. A 49 Coupe de Ville, Olds Holiday, Buick Rivera, looks very similar to a 50 Bel-Air or a 50 Pontiac Chieftain Catalina. If you don't like Cadillac styling , you probably don't like other GM cars as well.

As far as Chevy goes, they always used overhead valves, and Pontiac was held backfrom using their OHV V-8 because of Olds and Buick divisions asking corporate to hold Pontiac back for two years for fear of competition. Look at 53-54 Pontiac chassis, it's already designed for the V-8 and V-8's had millions of test miles to prove it. Pontiac's V-8 valve train was designed in 1948 and copied by chevy for their V-8.

Mass produced high octane fuel developed during WW2 gave the auto industry the ability to use overhead valves and high compression where the flat head combustion chamber could never go. By 1955 10.0 and higher compression's had already taken place and were going even higher.

D.

[Rusty_OToole]

You must have lived near Hollywood. As I said, Cadillacs were popular in some areas, but in more conservative parts they were considered too excessive and in bad taste. Unfortunately for Packard, too many buyers preferred Cadillacs, tailfins and all.

As for the speed of the Hudson vs the cars you mention I assume you mean in a straight line. It would not surprise me if the Chrysler was faster as it had a considerably larger, more powerful engine. Cadillac maybe, Olds it would be a close race. Remember we are considering like to like, a 308 Cu In 140 HP Hudson to a 303 Cu In 135 HP Olds.

The point is the flathead was not the klunker a lot of people imagine. In the late 40s and early fifties they could give comparable OHV cars a run for their money, and in the twenties and thirties they were superior. As you point out, by the mid fifties the contest was over and the OHV V8 was the champion.

This should not erase the very real merits of the flatheads of the past.

[Guest bkazmer]

good points made. The much touted 49 Cadillac OHV V8 had no power advantage on the Packard 356

[Rusty_OToole]

Buick, Chev and Nash all featured OHV engines before the Ricardo head came out. They must have felt they could not abandon them without losing face even if the flathead was a better engine.

Look up the statistics some time of HP per cubic inch for different engine designs, you will see the Buick Chev and Nash had little or no advantage over flatheads of similar size.

There was a very interesting comparison in 1927. In stock car racing, Stutz and Auburn had quite a battle that year. Both had straight eight engines, 288 cu in, the same bore and stroke, but one was an OHV design with overhead cam, the other a conventional flathead made by Lycoming.

In top speed on Daytona Beach that year the Stutz beat the Auburn but by less than 2 MPH.

The kicker is the Stutz was a $5000 car while the Auburn sold for less than $2000.

Another interesting comparison is Pierce Arrow vs Duesenberg. Between 1932 and 35 Pierce Arrow set 24 hour speed records on the Bonneville Salt Flats using a stock chassis, and a Pierce flathead V12 engine. The first year the engine and body were stock, the second year they had a more streamlined body and a slightly hopped up engine, the third year the same car with a more modified engine.

The next year Ab Jenkins beat the Pierce record with his Mormon Meteor, a car of similar size and overall appearance but with a double overhead cam, straight eight, supercharged Duesenberg engine and chassis.

The following year he came back and beat his own record with the same car, now equipped with a Curtis Conqueror aircraft engine.

Once again, the OHV proved slightly faster than the flathead but it took a supercharged OHC engine , and the Duesenberg was stretched to its limits to do it. Otherwise there would have been no point in changing to an aircraft engine the next year.

So it can be seen that in those days an OHV pushrod engine gave no power advantage over a good flathead, and even an OHC engine had a very small advantage.

Ford proved this for years. Their flathead V8 was the hottest car in its class, beating the flathead sixes and the OHV Chev as well. Ford was the hot car for a generation, from 1932 until the OHV V8s came out in the early fifties.

Until the high octane leaded fuels came out in the early to mid fifties, the flathead was king. It is fair to say that the old champion was beaten by a new champion but it is not fair to say he never had anything on the ball.

Edited August 24, 2011 by Rusty_OToole (see edit history)

[Layden B]

Just to set the record straight.. Buick did in the very early days offer a T head engined model and an L head engine. Neither are common but not all Buicks are overhead valves.

[Guest BJM]

And as 1947hd45 points out, it is a cheaper engine to make.

Cost can not be a consideration. To wit, Buick and Chevrolet and Nash used OHV engines and all 3 were high volume based. Yet luxury manufacturers such as Cadillac and Packard used flatheads, so cost wasn't the issue.

[Rusty_OToole]

Then there was the LeMans 24 hour race of 1928. First 2 finishers were Bentley and Stutz, both OHV cars with overhead cams and 4 valves per cylinder - out and out high performance or racing engines.

But 3d and 4th places were taken by Chryslers with flathead six cylinder engines.

They beat such highly rated sports cars as Alvis, Salmson, another Bentley and Lagonda.

It is also fair to point out that the Bentley and Stutz had bigger engines, 4.4 and 4.9 liters compared to the 4.1 Chrysler.

When you have the staying power to complete the 24 hours of LeMans, and finish in the money behind Bentley and Stutz, you have to have a hell of a motor.

The conventional pushrod OHV engines weren't in it with the flathead and OHC engines.

http://www.allpar.com/racing/lemans-1928.html

Edited August 24, 2011 by Rusty_OToole (see edit history)

[Rusty_OToole]

Cost can not be a consideration. To wit, Buick and Chevrolet and Nash used OHV engines and all 3 were high volume based. Yet luxury manufacturers such as Cadillac and Packard used flatheads, so cost wasn't the issue.

Nash used OHV engines only in their most expensive models, the cheaper ones were flathead powered. All Buicks were expensive cars in the upper medium price brackets. Why Chev stuck with the OHV engine I don't know. But Buick's short lived companion car, Marquette, had a flathead six.

Cost was just one consideration. But once the Ricardo head came out, the OHV engine was awfully hard to justify. A few firms continued to make OHV engine if they had done so in the past, but most went to the flathead.

Nash was head of Buick before he went out on his own and bought the Jeffrey company which he renamed Nash. So there was his connection to a successful OHV engine. I believe he started making Nash cars in 1917 so he had a reputation as an OHV engine supporter before the twenties.

Then there were the ultra luxury models. Most used a flathead design. Cadillac made an OHV pushrod V12 and V16 but only because their narrow angle design did not leave room for side valves. In the end they changed to a wide angle flathead V16 to go with their flathead V8.

Stutz and Duesenberg had overhead cams as well as overhead valves, these were the only OHV engines with a genuine performance advantage over a similar size flathead, but it was a small advantage, at what a cost!

[Guest]

You must have lived near Hollywood. As I said, Cadillacs were popular in some areas, but in more conservative parts they were considered too excessive and in bad taste. Unfortunately for Packard, too many buyers preferred Cadillacs, tailfins and all.

As for the speed of the Hudson vs the cars you mention I assume you mean in a straight line. It would not surprise me if the Chrysler was faster as it had a considerably larger, more powerful engine. Cadillac maybe, Olds it would be a close race. Remember we are considering like to like, a 308 Cu In 140 HP Hudson to a 303 Cu In 135 HP Olds.

The point is the flathead was not the klunker a lot of people imagine. In the late 40s and early fifties they could give comparable OHV cars a run for their money, and in the twenties and thirties they were superior. As you point out, by the mid fifties the contest was over and the OHV V8 was the champion.

This should not erase the very real merits of the flatheads of the past.

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No Rusty, I grew up in a middle class town still part of the city of L.A. called Westchester- near LAX, very conservative, however my dad owned a company in Hollywood from 1938-1965. BTW, Hollywood in those days compared to today would be considered conservative.

The point IS that the Hudson's flat head or the Packhard's is they were stretched to their limit at that time period while the OHV valve V-8 was mearly loafing, just getting started. Hudsons competed in NASCAR until 1955. The 7 X race engine was rated at 210 hp and the car would barely break 100mph on the sand at Daytona. Consider the 1957 Pontiac that won Daytona just two years later, 347 cubic inches, 317 Hp and top speed of just over 141 mph.

Don

[Guest BJM]

Buick had many lower mid priced cars especially during the Great Depression. Nonetheless I see your point.

I am eager to get these flatheads here and get to working on them. Sounds like fun.

[Rusty_OToole]

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No Rusty, I grew up in a middle class town still part of the city of L.A. called Westchester- near LAX, very conservative, however my dad owned a company in Hollywood from 1938-1965. BTW, Hollywood in those days compared to today would be considered conservative.

The point IS that the Hudson's flat head or the Packhard's is they were stretched to their limit at that time period while the OHV valve V-8 was mearly loafing, just getting started. Hudsons competed in NASCAR until 1955. The 7 X race engine was rated at 210 hp and the car would barely break 100mph on the sand at Daytona. Consider the 1957 Pontiac that won Daytona just two years later, 347 cubic inches, 317 Hp and top speed of just over 141 mph.

Don

Exactly. You nailed it. In 1957, a high compression engine would develop more power than a 1951, low compression engine. That is why the flathead fell by the wayside.

In 1947, the future was far from clear. Some very smart engineers and auto company executives thought the flathead was preferable to the OHV . Lincoln, Packard and Hudson were all planning new flathead engines at this time. What they did not know was that their plans would be thrown into disarray by the introduction of high test leaded gas of a type formerly used only in aircraft.

In 1937, or 1927, the flathead had it over the OHV engine, unless the OHV also had overhead cams and was specifically designed as a performance or racing engine. Even then, the advantage was small. When we are talking about ordinary cars that normal people would buy, the flathead was better.

Coming from California I am surprised you didn't know this. The Ford flathead V8 was the hot rod king for 20 years.

As for conservative motorists buying Cadillac over Packard you are also correct. I was trying to explain that in the 1945 to 1954 period Packard pursued a certain sales and marketing strategy that did not work out. Part of the strategy may have been the flathead straight eight engine which they pioneered in 1923 and which was strongly associated with the Packard brand.

When they started it looked like a good idea but public taste turned out to be more radical than they expected and engine developments progressed faster too. By the time they figured this out and revised their plans it was too late.

My point is the flathead is not the hopeless klunker some people think it is. You do not have to put a Chev 350 in everything in order to make it drivable. The old flathead still has a lot to offer as a reliable power plant even if it is not going to win any races except against another flathead.

Edited August 24, 2011 by Rusty_OToole (see edit history)

[Guest]

Exactly. You nailed it. In 1957, a high compression engine would develop more power than a 1951, low compression engine. That is why the flathead fell by the wayside.

In 1947, the future was far from clear. Some very smart engineers and auto company executives thought the flathead was preferable to the OHV . Lincoln, Packard and Hudson were all planning new flathead engines at this time. What they did not know was that their plans would be thrown into disarray by the introduction of high test leaded gas of a type formerly used only in aircraft.

In 1937, or 1927, the flathead had it over the OHV engine, unless the OHV also had overhead cams and was specifically designed as a performance or racing engine. Even then, the advantage was small. When we are talking about ordinary cars that normal people would buy, the flathead was better.

Coming from California I am surprised you didn't know this. The Ford flathead V8 was the hot rod king for 20 years.

As for conservative motorists buying Cadillac over Packard you are also correct. I was trying to explain that in the 1945 to 1954 period Packard pursued a certain sales and marketing strategy that did not work out. Part of the strategy may have been the flathead straight eight engine which they pioneered in 1923 and which was strongly associated with the Packard brand.

When they started it looked like a good idea but public taste turned out to be more radical than they expected and engine developments progressed faster too. By the time they figured this out and revised their plans it was too late.

My point is the flathead is not the hopeless klunker some people think it is. You do not have to put a Chev 350 in everything in order to make it drivable. The old flathead still has a lot to offer as a reliable power plant even if it is not going to win any races except against another flathead.

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Rusty you are right that the Ford flathead was the weapon of choice to hot rodders, but that was from 46-48, and as Cadillac's, Chrysler, Olds and Buick nail heads found their way into junkyards after accidents, they became the new weapon of choice for hot rodders. Now we finally come to the SB Chevy which changed the whole picture because now you had a engine that could make reasonable Hp at a fraction of the cost of rebuilding the afore mentioned engines. Which it is still why it is the engine of choice for them today. For myself, I like flatheads, especially Pontiac straight eights and Cadillac V-16 flathead (1938-40) and 346 V-8's. But if you want to make horsepower the flathead has major vises, inferior combustion chamber, and the inability to breathe due to small valve size and restrictive port design. Packard finally succumbed to the logic even though they were too late, plus they didn't listen to their own logic when they were touting the major achievements of the Packard-Merlin engine that were powering fighter planes in WW2. Ever see a flathead engine in a WW2 fighter?? Even WW1???

It is naive to think the General of U.S. war production didn't think about high octane fuel for automobiles of the future after all he was chairman of the board and ex president of GM Big Bill Knudsen. Remember the thread above where I said Pontiac had won Daytona in 1957, Bill Knudsen son Bunkie was the head of Pontiac division from mid 1956-to beginning production of 62 model Pontiac cars. Pontiac began work on the V-8 on paper before the war and had a all new valve train by 1948. Does anyone think they would have done all of this not knowing they would have adequate fuel to burn???

Don

[Guest Bob Call]

As for costs, the extra cost manufacturing the the dual rocker shaft hemi heads in all Chrysler division except Plymouth in the 1950's killed that head design ending with the 1958 model year. Beginning in 1958 Dodge and DeSoto began switching to the new high compression "wedge head" single rocker shaft engines. In 1959 the switch was complete with all divisions using the new V8's and the last year for Plymouth and Dodge flathead 6 in cars. The flathead 6 lived on for a few more years in Dodge and Fargo trucks and industrial applications.

[mrspeedyt]

all this talk makes me want to jump into my 'way back machine' and live the '50s as an adult instead of the little kid that I was.

question... what cars did the 'ricardo' engine come in?

Edited August 24, 2011 by mrspeedyt (see edit history)

[Guest Bob Call]

I don't know if any cars "came" with the Richardo head. Richardo figured out that turbulence in the intake passage and combustion chamber produced more power and that location of the major part of the combustion chamber directly above the valves and correct placement of the spark plug produced a controlled flame front and thereby reduced preignition knock or ping. The heads he made had the redesigned combustion chamber and relocated spark plug and produced more power that the "stock" head of a particular engine.

[Rusty_OToole]

There wasn't any "Ricardo" engine as such, except for a Triumph motorcycle of 1921 and 22. They sold a bike with a "Ricardo" head and advertised it as such.

Harry Ricardo was a researcher who developed new engines and cylinder heads for customers, they could be for cars, trucks, motorcycles, or whatever. In the thirties he did a lot of work on diesel engines.

If you can find a Dykes Encyclopedia or other technical automotive book from the early twenties you may find some discussion of the Ricardo head. It was adopted by all flathead engines eventually but usually without attribution.

Here is a link to a page from a 1927 Dykes giving details of the Ricardo head. Scroll down to see the actual page.

http://sites.google.com/site/rockislandg2/head-bolt-tensioning-pattern

There were actually different "Ricardo heads" for different applications. The Triumph mentioned above had an OHV engine and of course, there were different designs for diesels. But it was the flathead design that was commonly known as a Ricardo head in the US.

The Waukesha engine company made a "Ricardo head" in 1923 that was sold as such, making different ones for Model T Fords, Dodges, and other cars and trucks.

Edited August 24, 2011 by Rusty_OToole (see edit history)

[Rusty_OToole]

"But if you want to make horsepower the flathead has major vises, inferior combustion chamber, and the inability to breathe due to small valve size and restrictive port design."

It was the other way around. When the long stroke, small bore engine was in vogue it was the OHV engines that had small valves and restrictive breathing. Flatheads had the advantage that the valve chamber being beside the cylinder, could be wider than the cylinder with larger valves and more room around them for air flow.

I think you will agree the ports can be as large and well shaped on either engine, right up to the valve seats. The valves on the flathead can be larger and with more room around them. The only breathing restriction is the passage between the combustion chamber and cylinder.

This is where the compression ratio comes in. The more you lower the head, the more compression but the more restricted this passage becomes. If you go over about 7.5:1 you lose more in breathing than you gain in compression. Hudson and Packard overcame this to a certain extent by tipping the valves toward the cylinder and by some creative head design. But they still hit their limit at 8.7:1.

The new school of large bore, short stroke, OHV engines did not have these restrictions and of course, had a lot more scope for development.

But I think it is significant that the OHV advantage was very small as long as gas was below 80 octane and car makers were obliged to limit their compression to under 8:1.

I already gave the example of the 1949 Lincoln V8, long stroke flathead, 337 cu in 154 HP vs Cadillac, short stroke OHV V8, 331 cu in 160 HP.

Note that the "superior" OHV only develops 6 more HP than the "inferior" flathead. But both have a compression ratio of 7.5:1.

Meanwhile the 1951 Chrysler had the same bore and stroke as the Cadillac, the same compression ratio, but developed 180HP thanks to its hemi head design. This was a significant increase but at what a cost in money, complexity, and weight.

Chrysler eventually abandoned the hemi head design because it just wasn't worth it unless you were building a racing engine.

Only after 1951 did the OHV engines forge ahead as better gas allowed higher compression.

[mrspeedyt]

maybe my 'f' head jeep has the best of both worlds... (which came out for the 53's)

Edited August 24, 2011 by mrspeedyt (see edit history)

[Rusty_OToole]

The F head design had a lot to offer. It was used by such respected makers as Harley Davidson, Hudson, Rolls Royce, Rover and Jeep. But somehow it never caught on.

[Guest cben09]

On Packard 8 1923[1st series]old style head,,

1924[sept] [2nd series]1925 year model,,first year of Ricardo head

BUT the one port manifold persisted for a few years,,Ben

[Morgan Wright]

On 8/23/2011 at 10:44 PM, Guest BJM said:

I am in the process of restocking my shelves. I have one car in the garage, a 1973 Buick with a 455 OHV engine. That makes sense. By 1973 there were NO flathead engines left in the mainstream auto industry.

 

It makes even more sense when you consider that Buick NEVER made a flathead engine. Their first OHV engine was in 1904, which happened to be the first Buick ever made. They did make a T-head engine in Jackson Michigan around 1910, briefly, but the Flint factory never made anything but OHV for over 100 years.

 

Buick = valve in head.

 

[Morgan Wright]

By the way.....the OHV engine was invented by Walter Marr, chief engineer at Buick starting in 1899.

[padgett]

The other issues with a flathead is the distance the flame front needs to travel for full combustion and the fact that only a fraction of the combustion pressure is against the piston. Going to avoid all the math but OHV made high(er) compression possible, then the hemi  came along (NYC garbage trucks) to minimize the flame front travel by having a spherical chamber with a center plug (so why do modern hemi-V-8s need 16 spark plugs ?). However current hemis can only have two valves so the most modern designs are a DOHC with a pentroof 4 valve head just like a 1928 Duesenberg.

[Spinneyhill]

I believe Peugeot had hemi-spherical combustion chambers on their grand prix cars of about 1904.

[padgett]

Peugeot also had a bevel shaft driven OHC AFAIR. Current SOA seems to be a pent roof center plug four valve DOHC head. Though since lead is gone and valves no longer need to rotate have wondered about  dual stem lozenge shaped valves. That said with direct injection and boost, chamber shape is more important than valve area.

[Guest]

Just by the way a "T head" is a flat head as is "L head".  The others are OHV or valve in head and then there is that funny "F head" neither fish nor fowl.  I suppose a two stroke could also be called a flat head???

[padgett]

And a Knight sleeve valve ?

[Larry Schramm]

9 hours ago, Morgan Wright said:

 

It makes even more sense when you consider that Buick NEVER made a flathead engine. Their first OHV engine was in 1904, which happened to be the first Buick ever made. They did make a T-head engine in Jackson Michigan around 1910, briefly, but the Flint factory never made anything but OHV for over 100 years.

 

Buick = valve in head.

 

 

By the way, Buick did make a flat head engine I believe only one year and it was in 1913 for the Buick Truck.  I have personally seen this truck and the documentation.

 

Please see post #74 for explanation.  http://forums.aaca.org/topic/282329-buick-trucks/?page=3

Edited November 16, 2016 by Larry Schramm (see edit history)

[Morgan Wright]

13 hours ago, Larry Schramm said:

 

By the way, Buick did make a flat head engine I believe only one year and it was in 1913 for the Buick Truck.  I have personally seen this truck and the documentation.

 

Please see post #74 for explanation.  http://forums.aaca.org/topic/282329-buick-trucks/?page=3

 

Was this made in the Jackson, Michigan plant? Because there was the T-head model D 4-cylinder Buick of around 1910, made in Jackson, under Marr's protest (Billy Durant OK'd it). But as long as Walter Marr was in charge of the Flint factory, anything but valve-in-head were words that could not be uttered there.

 

I don't know if Peugeot made an OHV engine in 1904 but the first production car in the world with OHV was Marr's Autocar, which not only had OHV in 1903, but had overhead cams as well. World's first on both counts. But his first OHV car was his experimental trike of 1898.

[Layden B]

Buick 1907 Models D,S,H, and K are T heads, 1911 Model 14 is an L head, all other Buicks are overhead valves.

Sorry I do not know what factory these were made in but they put to rest the fiction that all Buicks have overhead valves.

[Morgan Wright]

I knew about the Model D