F Head Engine

[Hudsy Wudsy]

This isn't very important, I just thought that maybe a couple of you may have never seen an F head engine. This is a picture I borrowed from the Hudson Forum right here on AACA. It's the engine in a '28 Hudson that someone is offering for sale. If you aren't familiar with the term "F head", it doesn't have anything to do with the term "flathead". An F head engine has intake valves in the cylinder head, but exhaust valves in the block. Most of you know this, but maybe some of the younger members might not. Here's a link to the thread:http://forums.aaca.org/topic/280754-1928-hudson-super-six-brougham-formal-sedan-for-sale/

 

[joe_padavano]

This cross section might help folks understand where the "F" comes from.

 

[Ben Bruce aka First Born]

Well, even some of us old folks just learned something. Thanks, guys.

 

  Ben

[Dandy Dave]

The Jeep Hurricane engine was also a F head. There were thousands of these back in the day. 

 

Jeep Hurricane Engine. 

 

[Ron Lawson]

The English Landrover also had a F Head engine back in the 1960s

[Xander Wildeisen]

I had a 28 Hudson 3 window coupe, with  that engine. Great motor, car came with a oil can from the factory mounted on the engine. Had to lit the caps on top of the valves and oil daily. 

[plymouthcranbrook]

So, what was the reasoning that an F type head was used instead of a OHV head with both valves in it?  Manufacturing issues or? Was always curious.

[Guest]

One thing the design did was to allow for larger valves therefore better breathing.

[joe_padavano]

41 minutes ago, plymouthcranbrook said:

So, what was the reasoning that an F type head was used instead of a OHV head with both valves in it?  Manufacturing issues or? Was always curious.

 

I always assumed the F head was an interim step on the evolutionary path from flathead to full OHV. It might have been easier to cool the exhaust valves by keeping them closer to the block's cooling jacket, for example.  As metalurgy and cooling system design evolved, this became less of an issue.

[JACK M]

The push rod is a rocker arm?

[Hudsy Wudsy]

45 minutes ago, plymouthcranbrook said:

So, what was the reasoning that an F type head was used instead of a OHV head with both valves in it?  Manufacturing issues or? Was always curious.

I don't honestly know for sure, but I do know that exhaust valves must have played a role. I think that the "F" head configuration was seen as a compromise. Exhaust valves dissipated heat better in flathead engines than in overhead ones. With the crummy fuels that were available at the time, burnt valves were always a threat. That's probably one of the reasons that the flathead prevailed for so many years. Of course it was less expensive to manufacture as well. Flatheads, however, with their valves alongside the combustion chamber, rather than over it (like overhead valves) could never be made to breathe as well as overhead valve engines. The post war ear brought about a desire for better performance from engines, so the overhead valve engines began to replace the flatheads. I've always assumed that the adoption of overhead engines is what brought about the need for better cooling systems and, thus, the need for pressurized radiators.

[JV Puleo]

It's a very common early engine design, often referred to as "IOE" for "intake over exhaust". There are also "EOI" engines with the exhaust on top and the intakes on the side. I suspect it was a natural development from the T-head, allowing the use of only one cam shaft and one set of timing gears as well as simplifying the combustion chamber design.

 

The design long pre-dates the detachable head. It also allowed larger valves with a single cam since they didn't have to be next to each other. On non-detachable head engines, the valves on top were carried in removable valve cages and could be worked on without dismantling the remainder of the engine. It may be the most common configuration for medium sized brass cars.

Edited August 17, 2016 by JV Puleo
additional information/grammar (see edit history)

[Hudsy Wudsy]

38 minutes ago, JV Puleo said:

It's a very common early engine design, often referred to as "IOE" for "intake over exhaust". There are also "EOI" engines with the exhaust on top and the intakes on the side. I suspect it was a natural development from the T-head, allowing the use of only one cam shaft and one set of timing gears as well as simplifying the combustion chamber design.

 

The design long pre-dates the detachable head. It also allowed larger valves with a single cam since they didn't have to be next to each other. On non-detachable head engines, the valves on top were carried in removable valve cages and could be removed, and worked on, without dismantling the remainder of the engine. It' may be the most common configuration for medium sized brass cars.

Fascinating. I had no idea.

[A. Ballard 35R]

Don't forget the most famous early American race car that had side exhaust valves and overhead intake valves operated by pushrods and rocker arms. Unlike more modern F head designs, there were two camshafts for the 1,197 cubic inch engine. The car as many have probably guessed is the 1908 Locomobile racer, winner of the 1908 Vanderbilt Cup and commonly referred to as "Old 16". David Greenlees on his website www.theodlmotor.com has several interesting pieces on this amazing car.

[CarlLaFong]

6 hours ago, Ron Lawson said:

The English Landrover also had a F Head engine back in the 1960s

So did Bentley

[JV Puleo]

The Mark VI Bentley and Silver Cloud I RRs used the same basic F head engine, starting in 1947.

[Hudsy Wudsy]

JV, I thank you for your contribution here. I Googled "T" head engine, and with the info you shared about the "F" head, I have a better grasp of the whole evolution of internal combustion engines than I had before.

 

Here's a quick look at the "T" head engine:

[Rusty_OToole]

The F head was a performance engine in the day of long stroke, small bore engines.

 

In those days the designer had a choice of a more efficient OHV layout with small valves, restricted by the bore diameter

 

Or a flathead design which did not limit valve diameter, but had a less efficient combustion chamber shape and compromised compression and breathing

 

The F head offered unlimited valve area, a more compact combustion chamber for higher compression without compromising breathing.

 

The Hudson F head "Super Six" was an outstanding performer in its day. The F head was popular in England on expensive cars like Bentley, Rolls Royce, and Rover.

 

When the modern big bore, short stroke type of engine came in after WW2 the OHV engine was the best layout and the F head and flathead fell by the way side.

 

For the sake of completeness I might point out the hemi head OHV layout was the most efficient of all, but was considered too complicated and expensive for anything but a racing car or very expensive performance car, before Chrysler brought out their Hemi V8 in 1951.

Edited August 18, 2016 by Rusty_OToole (see edit history)

[Rusty_OToole]

From the 20s through the 40s the flathead layout was the most popular, and the most practical from the standpoint of cost, simplicity, silence, and long trouble free service.

 

Some companies like Chevrolet and Buick stuck with the OHV layout because they had always used it, but got little or no benefit in power or mileage.

 

To put it in a nut shell the F head was a combination of both, and offered performance and economy advantages over both.

Edited August 18, 2016 by Rusty_OToole (see edit history)

[JV Puleo]

i don't know about Rover but all pre-war RRs had either side valves (the Silver Ghost) or overhead valves (the Phantom series and the small HP cars.) All of the pre-war Bentleys had an overhead cam (with the exception of a very short lived OHV Bentley made as the company was dying. It wasn't until after WWII that the F-head came in, based on a war-time light truck engine that the company made thousands of. I think those may have been used in war-time Rovers but I stand ready to be corrected. The smaller engine was based on the pre-war small HP engine, all of which had the same center-to-center dimension for the cylinders. That engine had been continuously developed since the early 20s but, as Rusty correctly suggests, they simply ran out of space for increasing the size of the valves and had to adopt the F-Head design. At the time, it was criticized as a backward step.

Edited August 18, 2016 by JV Puleo
typo (see edit history)

[sleeve-valve]

Harley Davidson had an F head engine thru 1929. Here is a pic of my 1928 JD with the 74 ci F head engine.

[plymouthcranbrook]

Great information, thanks. Lots I had no idea about 

[Hudsy Wudsy]

The prewar RR 8 cyl flathead was so similar to the Hudson eight, which preceded it, that it was joked about in Hudson circles.

[JV Puleo]

21 minutes ago, Hudsy Wudsy said:

The prewar RR 8 cyl flathead was so similar to the Hudson eight, which preceded it, that it was joked about in Hudson circles.

 

There was no pre-war 8 cylinder RR. They were all sixes except the Phantom III which was a V12. RR didn't make any 8 cylinder engine until the post war V8 used in the Cloud II and S-type Bentleys. They've never made a flathead either.

[nick8086]

  Sounds like a Jeep motor..

Edited August 18, 2016 by nick8086 (see edit history)

[Hudsy Wudsy]

I apologize for my mistake. I'm at a loss to think of which manufacturer I am talking about.

[JV Puleo]

There's nothing to apologize for...

 

I found this reference last night in Gasoline Automobiles by P.M. Heldt – an automobile engineering textbook (1911 edition)

 

He gives these statistics...

At the Madison Avenue Auto Show in January of 1911, 40% of the passenger car engines were T-heads, 38% were L-Heads and 12.5% had overhead valves. Obviously these numbers don't add up to 100% so I presume that the remainder had some odd arrangement not usually seen, like my 1910 Model T Mitchell which has a form of L-head except that the exhaust valves are on the top and the intake valves are on the side or an overhead cam shaft which he mentions in his book but comments they are rarely seen in the United States.

 

But, these figures reflect automobile makers, not numbers of cars on the road. Since the T-head was quite a bit more expensive to produce, virtually all the cars that used it were expensive, low production vehicles so there were probably far more L-head engines in use than T-heads — at least at this point.

 

 

Edited August 18, 2016 by JV Puleo (see edit history)

[Rusty_OToole]

There may have been a few 2 stroke, sleeve valve, electric, and steam cars at the  1911 auto show that would account for the other 9.5%.

[jp928]

The  Rover IOE engines  Used  a failry wide block to enable the exhaust valve head to form one side of the combustion chamber, and with a sloping head joint and a ridged piston crown there was a nearly hemispherical chamber. See about halfway down the page at http://www.curbsideclassic.com/automotive-histories/automotive-history-the-curious-f-head-engine/

They started in 48 with 1.6 and 2.1L 4 and 6 cyl engines, of 60 and 75hp. Early Land Rovers used the 4 cyl for many years. The early cars used rockers with chromed curved faces running on the cam, but they were not long lived as they might have been if oil got dirty. There were 4 and 7 main bearing versions in 2.6L models. Some of the 6s appeared in LRs as well, but they were a bit too maintenance intensive to be satisfactory. Later versions used roller followers running in lead lined bronze rockers which lasted much better - these are visible in the cross section on the web page above. The last engine (3L) lasted into the 70s in the P5 sedan. 

 

When I had Rovers of this era, and knew many other owners, we used to get asked if we had any spare inlet valve rockers  - by Bentley owners. The Rover tappet adjusters (the threaded part) were ball ended with a little cap clipped on , to improve valve action and reduce wear. These apparently fitted the Bentley rockers, and were somewhat cheaper than genuine items.

 

 

FWIW Rolls made a V8 in 1905, 3 cars made, 1 sold, engine unsatisfactory, bought back and scrapped.

 

jp 26 Rover 9

Edited September 27, 2016 by jp928 (see edit history)

[1937hd45]

The Riley 2 and 4Port heads for Model A & B engines were F Head designs. This is a 2Port. Bob

[imnuts4fords@comcast.net]

I have 2 vehicles with F-heads.  The first is a 1909 Chalmers Detroit and the other is a 1913 Indian.  The F-head design allowed the intake valve to be larger and directly over the piston.  Except for the Mitchell automobile.  Their early F-head was exhaust over the intake.  I kid a good friend that they built their engine backwards.  We also installed the later F-head engine in a '47 Willys Jeep replacing the flathead to gain a little power.  I think a design advantage was to separate the hot gases surrounding the exhaust valve port from the intake valve port and distance the exhaust manifold from the carb.

[nick8086]

https://minneapolis.craigslist.org/hnp/cto/5773052556.html

 

This car has one..  161c.i. 6 cyl F-head.

Edited October 1, 2016 by nick8086 (see edit history)

[Frankyboy]

Hi guys I have a McKee F head set up, think they only made 6 sets, any body out there that can give me any information on these? Or what they should look like when there built up ?

 

[Ivan Saxton]

Best basic information on design considerations of the F -head is Sir Harry Rickardo's  "High Speed Internal Combustion Engine" This was text book for mechanical engineers for many decades.   He was instrumental in RR and post-Bentley Bentley using F-head.    Do not forget that Rajo 4 valve heads for T Ford were F-head.    It is interesting that the very first high efficiency high compression engines were 1907 Isotta Fraschini Tipo Taunus.  These were an 8 litre displacement 4 cylinder T-head, with stroke shorter than the bore size.  The piston crowns were highly domed, and nearly touched the combustion chamber  roof.  Having a spark plug each side firing synchronously by a 2-spark Bosch Magneto which had In the 1907 Coppa Florio race,  Ferdinando Minoia won at average speed of 69mph. You could liken this to a double-sided Rickardo patent L-head engine.  It was effectively "prior art " to Rickardo's 1917 patent.   Minoia used 19.8 imperial gallons of fuel in the race over 302 miles.   Fifteen miles per gallon from a big T-head !!!!!  No owner of a big Locomobile or Pierce could comprehend that;  and probably Giustino Cattaneo did not understand what he had achieved. ……  You can pick this from the early racing chapter, and an engine cross section drawing in Angelo Tito Anselmi's book Isotta Fraschini.  I don't think author Anselmi recognized the historical and technical achievement either.

[Frankyboy]

55 minutes ago, Ivan Saxton said:

Best basic information on design considerations of the F -head is Sir Harry Rickardo's  "High Speed Internal Combustion Engine" This was text book for mechanical engineers for many decades.   He was instrumental in RR and post-Bentley Bentley using F-head.    Do not forget that Rajo 4 valve heads for T Ford were F-head.    It is interesting that the very first high efficiency high compression engines were 1907 Isotta Fraschini Tipo Taunus.  These were an 8 litre displacement 4 cylinder T-head, with stroke shorter than the bore size.  The piston crowns were highly domed, and nearly touched the combustion chamber  roof.  Having a spark plug each side firing synchronously by a 2-spark Bosch Magneto which had In the 1907 Coppa Florio race,  Ferdinando Minoia won at average speed of 69mph. You could liken this to a double-sided Rickardo patent L-head engine.  It was effectively "prior art " to Rickardo's 1917 patent.   Minoia used 19.8 imperial gallons of fuel in the race over 302 miles.   Fifteen miles per gallon from a big T-head !!!!!  No owner of a big Locomobile or Pierce could comprehend that;  and probably Giustino Cattaneo did not understand what he had achieved. ……  You can pick this from the early racing chapter, and an engine cross section drawing in Angelo Tito Anselmi's book Isotta Fraschini.  I don't think author Anselmi recognized the historical and technical achievement either.

That sounds like a good read, cheers

[Turbine Tech]

Chrysler had an experimental F head V8 back in 1945.