How did Flathead Motors Hang on So Long?

[Rusty_OToole]

9 hours ago, Tom Boehm said:

New question about flathead engines: A method I have heard of to revive engines that have sat unused for a long time is to remove the spark plugs and fill the cylinders with Marvel Mystery Oil. If the engine is suspected of being stuck the MMO soak could loosen it up. Is this method possible with a flathead engine? If a valve is open, wouldn't the MMO fill the intake or exhaust manifold rather than filling the cylinder? Especially if the spark plug is over the valves and not centered on the cylinder. 

In my experience of old engines left sitting for a long time flathead engines are more prone to valves sticking, OHV engines more prone to pistons and rings sticking. This could be because moisture tends to settle at the lowest point in the cylinders and cause rust.

 

If the sticking is not too bad some kind of penetrating oil in the cylinders and valve may be all it needs to get running, and once it is running the heat and vibration helps loosen things up.

[Bloo]

9 hours ago, Harold said:

On Plymouths I've used a pump oiler with a long, skinny flex nozzle.  I go in through the spark plug hole and aim the nozzle towards the driver's side of the engine to get the lubricant above the piston where it has to go.

 

Exactly. You have to get over where the cylinder is. A Zoom Spout bottle also works.

 

Edited December 24, 2023 by Bloo (see edit history)

[B Jake Moran]

Or take the head off?  Again I’m no flathead expert, that’s partly why I asked the initial questions.  

[Rusty_OToole]

There  is a site on Youtube called Cold War Motors where  they have revived a number of old flathead and overhead valve motors. The owner Scott Newstead lets on to be a hack but he knows what he is doing. He just hates to spend money. Have taken apart and got running, several hopeless cases.         

You could start with this straight eight showdown where they revive a flathead Packard and an OHV Buick. Both were bought as basically junkers that had not run in 30 years or more.

    

                  

[Ben Bruce aka First Born]

12 hours ago, Rusty_OToole said:

There  is a site on Youtube called Cold War Motors where  they have revived a number of old flathead and overhead valve motors. The owner Scott Newstead lets on to be a hack but he knows what he is doing. He just hates to spend money. Have taken apart and got running, several hopeless cases.         

You could start with this straight eight showdown where they revive a flathead Packard and an OHV Buick. Both were bought as basically junkers that had not run in 30 years or more.

    

                  

That was a fun one. 

 

  Ben

[Hemi Joel]

During the waning years of the flathead era, there were a whole lot of drivers, my grandparent included, who had lived through the depression and as a result were very thrifty. Low cost upfront, low operating costs such as good fuel economy were most important. Driving over 55-60 was not done. The flatheads filled the demand in this market segment.

[Leif in Calif]

On 12/14/2023 at 11:52 AM, Rusty_OToole said:

In the early days meaning before 1920 there were a variety of engine designs tried. Flathead, T head, and OHV engines were popular. Duesenberg made an excellent engine with the valves at 90 degrees to the cylinders called a Walking Beam engine.

 

Flatheads were popular because they were simple, quiet, cheap to build, easy to repair, and if you broke a valve spring (which was a common thing at the time) it did no harm as the valve could not crash into the piston.

 

But the OHV engines, while more expensive, complex and noisier had a slight advantage in efficiency.

 

Then came a major breakthrough called the Ricardo cylinder head. Invention of an English inventor Harry Ricardo and brought to the market in 1922. It introduced the idea of squish or quench. This did 2 things, it reduced the effective size of the combustion chamber at TDC and it caused turbulence. This allowed higher compression and faster combustion.

 

With the new high compression Ricardo design OHV engines had little or no advantage over a flathead. While the flathead still had all the advantages above. Plus, you could use bigger valves in a flathead. With the valve chamber beside the cylinder, it could be wider than the cylinder, while OHV engines were restricted to the diameter of the cylinder. This was an important point with the small bore, long stroke engines then in vogue.

 

So, from 1922 on, the flathead held all the cards. This is why there were practically no new OHV engines from then on, with the exception of a few old line companies that were committed to the OHV principle, and some all  out racing engines with hemi heads, that would do anything to eke out a few more Horsepower.

 

This was the rule until the early fifties. There were several technical developments that led to the use of OHV engines, the biggest one being the use of high octane leaded gas.

 

Top compression ratio for a flathead is about 7.5 or 8:1. The highest I know of is 8.2:1 in a 1954 Packard straight eight, and they had to pull every trick in the book to get it that high.

 

If you raise the compression beyond a certain point you cut off the breathing. This is not an issue with OHV engines.

 

Now you know why the flathead was king from the early twenties to the early fifties, and why the OHV took over. There is still nothing wrong with a good flathead. They are smooth, reliable, quiet and a pleasure to drive as the long stroke and high torque make driving easy with almost no shifting required. And with low compression they run fine on the lowest octane regular, in fact, they run better on low octane fuel than high octane.

 

If you want to go fast you need an OHV V8 but for driving pleasure a good flathead is hard to beat.

 

By the way don't think all flatheads are deadheads on the road. The big Packard 400 straight eight could top 100MPH and was only a few tenths of a second behind its OHV competitors in acceleration.

Exactly right! I wonder if the OHVs of early Chevys and Buicks was as much a marketing ploy as a performance enhancer. The disadvantages of the flathead did not show themselves until advancements in fuel and metals allowed higher RPMs and higher compression. At 5 or 6 to one compression and a max of 3,000 RPM, there is no advantage to OHVs, only higher production and maintenance costs. 

[Marty Roth]

2 minutes ago, Leif in Calif said:

Exactly right! I wonder if the OHVs of early Chevys and Buicks was as much a marketing ploy as a performance enhancer. The disadvantages of the flathead did not show themselves until advancements in fuel and metals allowed higher RPMs and higher compression. At 5 or 6 to one compression and a max of 3,000 RPM, there is no advantage to OHVs, only higher production and maintenance costs. 

Leif,

 

I would debate that premise from an efficiency point of view.

I believe the OHV configuration, as opposed to L-head, F-head, Flathead, etc tended to provide improved "breathing",

reduced carbon buildup on pistons and valves, reduced frequency of maintenance, easier valve adjustment when needed, and likely some others I've forgotten.

Low-end Torque may indeed become a factor.

In 1928, Chevrolet's new cylinder head was designed around dual exhaust ports for even better breathing, and flow of exhaust gasses

[human-potato_hybrid]

On 12/14/2023 at 2:52 PM, Rusty_OToole said:

Top compression ratio for a flathead is about 7.5 or 8:1. The highest I know of is 8.2:1 in a 1954 Packard straight eight, and they had to pull every trick in the book to get it that high.

 

By the way don't think all flatheads are deadheads on the road. The big Packard 400 straight eight could top 100MPH and was only a few tenths of a second behind its OHV competitors in acceleration.

Some interesting statistics on the best Packard engine money could buy in the mid-50's:

1954: 212HP, 8.2:1, 359ci flathead 8

1955: 275HP, 8.5:1, 352ci V8

1956: 310HP, 10.0:1, 374ci V8

 

Look at the HP jump with barely any change in compression or displacement when changing from the flathead to V8. That being said, the Packard flathead 8's were wonderful engines that Packard made in various forms for nearly 20 years straight and so had time to perfect. Dead reliable and easy to repair, still with sufficient power and torque for any reasonable driving style.

[human-potato_hybrid]

@Gary_Ash https://web.archive.org/web/20210227010519/http://uncommonengineering.com/

 

Thank the Internet Archive!!

[Rusty_OToole]

3 hours ago, human-potato_hybrid said:

Some interesting statistics on the best Packard engine money could buy in the mid-50's:

1954: 212HP, 8.2:1, 359ci flathead 8

1955: 275HP, 8.5:1, 352ci V8

1956: 310HP, 10.0:1, 374ci V8

 

Look at the HP jump with barely any change in compression or displacement when changing from the flathead to V8. That being said, the Packard flathead 8's were wonderful engines that Packard made in various forms for nearly 20 years straight and so had time to perfect. Dead reliable and easy to repair, still with sufficient power and torque for any reasonable driving style.

The straight eight and V8 are not strictly comparable just on a flathead vs OHV basis. The new OHV engine was a short stroke, big bore vs long stroke small bore design the V8 configuration with 5 main bearings had a shorter, stiffer block and crankshaft. The old engine was a long stroke, high torque design with a wide power band, the new one a short stroke low friction higher RPM type better suited to automatic transmissions and the new high speed interstate highways.

 

No doubt in the fifties the new OHV engines had the advantage partly due to better high octane fuels but there were other factors at work. For a long time I thought the old flatheads were obsolete junk made by guys who didn't know how to design and build a good engine.  I found out this was wrong. The old flatheads had merits of their own and during the period of 1922 to the early fifties, had it over the OHV engines. Today I have more respect for the practical virtues of the old flatties and less interest in having the fastest car on the block.

[Leif in Calif]

5 hours ago, Marty Roth said:

Leif,

 

I would debate that premise from an efficiency point of view.

I believe the OHV configuration, as opposed to L-head, F-head, Flathead, etc tended to provide improved "breathing",

reduced carbon buildup on pistons and valves, reduced frequency of maintenance, easier valve adjustment when needed, and likely some others I've forgotten.

Low-end Torque may indeed become a factor.

In 1928, Chevrolet's new cylinder head was designed around dual exhaust ports for even better breathing, and flow of exhaust gasses

I absolutely agree Marty, that's why there are no flatheads today. I'm just saying that those benefits didn't really show themselves until compression ratios and RPMs went up. I'm very familiar with the 4 cylinder Chevy, and adding that second exhaust port in '28 made a BIG improvement, but it was still a couple of hp down from the then new model A, and it had to be more expensive to manufacture. 

[Rusty_OToole]

As long as we are at i

6 hours ago, Marty Roth said:

Leif,

 

I would debate that premise from an efficiency point of view.

I believe the OHV configuration, as opposed to L-head, F-head, Flathead, etc tended to provide improved "breathing",

reduced carbon buildup on pistons and valves, reduced frequency of maintenance, easier valve adjustment when needed, and likely some others I've forgotten.

Low-end Torque may indeed become a factor.

In 1928, Chevrolet's new cylinder head was designed around dual exhaust ports for even better breathing, and flow of exhaust gasses

As long as we are at it why not compare OHV to flathead motors in the low priced field in 1930. I chose that year because someone brought up the Model A and because it is easy to find stats for that year.

 

Chevrolet had a new 6 cylinder engine that presumably showed the best they could do. Ford had an equally new 4 cylinder.

 

Chevrolet six - OHV - 193.9 cu in - 5:1 compression - 50HP @ 2600 - .257 HP per cu in

 

Ford A four - flathead - 200.5 - 4.22:1 - 40HP@2200 - .199 Hp per cu in

 

Plymouth 4 - flathead - 196.1 cu in - 4.6:1 - 48HP@2800 - .245 HP per cu in

 

Hudson Essex 6 - flathead - 161.4 - 5.8:1 - 58@3300 - .359 HP per cu in

 

Ford has the lowest compression and the lowest HP per cubic inch.

 

The Essex  has the highest HP, highest compression and highest HP per cu inch. So it is not surprising they were considered the hot performer among low priced cars.

 

Chev and Plymouth are very close even though one is an OHV six and the other a flathead four.

 

Chevrolet has a slight advantage over the others in HP per cu in except for Essex, which has higher compression.

 

If you rank them in order of HP per cu in and compression ratio, you will see the lists are the same. In other words compression ratio and efficiency seem to be closely related.

 

This is why the Ricardo head was such a breakthrough.

 

The Chevrolet may have had many merits which earned it first place in sales. But the super performance of the OHV engine isn't one of them. Yes it has a slight advantage over its main competitors (except Essex) but the difference is not huge. This is why I say that after the Ricardo head became popular the only companies that made new OHV engines were companies like Chevrolet, Buick and Nash that were committed to the OHV principle come what may. And companies like Duesenberg and Stutz that were after the ultimate in luxury  regardless of cost.

Edited December 28, 2023 by Rusty_OToole (see edit history)

[Ben Bruce aka First Born]

12 hours ago, Rusty_OToole said:

The straight eight and V8 are not strictly comparable just on a flathead vs OHV basis. The new OHV engine was a short stroke, big bore vs long stroke small bore design the V8 configuration with 5 main bearings had a shorter, stiffer block and crankshaft. The old engine was a long stroke, high torque design with a wide power band, the new one a short stroke low friction higher RPM type better suited to automatic transmissions and the new high speed interstate highways.

 

No doubt in the fifties the new OHV engines had the advantage partly due to better high octane fuels but there were other factors at work. For a long time I thought the old flatheads were obsolete junk made by guys who didn't know how to design and build a good engine.  I found out this was wrong. The old flatheads had merits of their own and during the period of 1922 to the early fifties, had it over the OHV engines. Today I have more respect for the practical virtues of the old flatties and less interest in having the fastest car on the block.

 

 LOL.  We do change as we age!   

 

  Ben

[Pfeil]

1. here we have the Packard 6-12 1932-39. The valves are in the block, yet they are located over the pistons.

 

 

Here we have Oldsmobile's companion car Viking's V-8. Valves are also over the pistons.

 

Here we have the 31-32 Oakland/Pontiac V-8, valves are over the pistons as well as combustion chambers.

notice valves over the pistons. The block and head mating is on 2 planes.

 

[Buffalowed Bill]

On 12/15/2023 at 11:14 AM, rustyjazz1938 said:

@Rusty_OToole, I'd like to offer a counter to your statement. In discussions with @Stude Light, we both came to the realization that his 1923 Studebaker Light Six and my 1927 Buick Standard 27-27 have the same displacement engine. Both have 3.125in bore by 4.5in stroke for a displacement of 207 cubic inches. The Studebaker is a flathead engine whereas of course, the Buick is OHV. Factory ratings (always taken with grain of salt) were 63 HP for the Buick, and I believe 35 HP for the Studebaker (Scott please feel free to correct me). I believe the compression ratio for the Buick was in the 6:1 or slightly higher range which was high for the era, I don't know the number for the Studebaker.

 

It really isn't an apples to apples comparison of course as age/price point differences come into play, but I felt it would be a valid observation to share that given the same displacement, one engine makes 28 horsepower more than the other with one major difference being OHV configuration versus flatheads.

 

I won't get into the fact that the Buick being a significantly heavier car, the overall vehicle performance is about the same... 🤪.

 

Just my two cents in the discussion.

 

Happy Motoring,

 

Rusty

Just a couple of comments regarding the Light Six Studebaker analogy. That engine was redesigned several times, the first of which became standard mid-year. It has to be remembered that Studebaker did not follow any set year-to-year new models, based on the calendar. They continued to make running changes as improvements became available. The new engine included a larger bore, higher compression ratio and full pressure oiling to all bearings. The changes resulted in a jump in HP to a stated 50HP. Is this splitting hairs too? I really don't know, but the new engine was a lot different then the old version!