20 replies to this topic

[AAGR]

Morning all. This is a really long shot.

 

From 1950 to 1953, Healey entered several Nash-Healeys in the Mille Miglia and the Le Mans 24 Hour race.

 

In 1952, at Le Mans, one of the 'works' cars used a very special 4.2-litre engine, which was described as having a special cylinder head with inclined valves and hemispherical combustion chambers, the valves being operated rather on the lines of the BMW design..

 

Nothing more was ever published about this engine which, as far as I know, was never used again. Does anyone know what it was, where it came from, and who designed it ?

 

 

[nicanary]

Morning all. This is a really long shot.

 

From 1950 to 1953, Healey entered several Nash-Healeys in the Mille Miglia and the Le Mans 24 Hour race.

 

In 1952, at Le Mans, one of the 'works' cars used a very special 4.2-litre engine, which was described as having a special cylinder head with inclined valves and hemispherical combustion chambers, the valves being operated rather on the lines of the BMW design..

 

Nothing more was ever published about this engine which, as far as I know, was never used again. Does anyone know what it was, where it came from, and who designed it ?

According to Mike Lawrence's book, the head was the work of A C Sampietro who was Donald Healey's business partner. Lawrence stresses that it produced a "claimed" 200bhp.

[Ray Bell]

Wouldn't this have been a fairly heavy engine?

And with somewhat heavy internals which would have held back performance?

[Ray Bell]

And to add another question, did the design for the head for the Austin Healey 4000 come from the same source?

[PJGD]

Achilles Carlos Sampietro was a very creative Italian engineer who gained three PhD's, in mathematics, electrical engineering, and physics.  He moved to England to avoid Mussolini and lived there for 25 years before moving to the US in the mid 1950's.  According to Sam Heron who thought highly of him, Sampietro spent much of his career as a consultant, working for companies such as Humber, Simca, TRW, Kaiser-Willys, and latterly Ford.  He also worked with Reid Railton for Robot Gearing Ltd.

 

He accumulated many patents over the years; take a look at: https://worldwide.es...e=1&return=true

 

There are within that long list many patents relating to overhead valvegear, it was obviously an area of strong interest to him, but I am confident that the patent of interest to you in relation to the Healey engine will be US2744513:

 

Somehow, the English version of many of his patents seem to have gone missing.

 

PJGD

[Vitesse2]

Flight (October 6th 1938, p310) mentions Sampietro's UK patent 491664 for 'control means of land vehicles, aircraft and water craft'. Which, if you think about it, is somewhat intriguing. There are possibly more to find, but obviously Flight was only concerned with aviation matters.

 

Also some others from the 1940s and 1950s recorded in Commercial Motor: http://archive.comme...?term=Sampietro

[3353u]

The Nash Hemi Le Mans Racing Heads were designed by one of Donald Healey's engineers by the name of A C (Sammy) Sampietro. There were only three made.  The task of manufacture was given to Ken Taylor of Thompson and Taylor based at Brooklands Surry. All three were used at LeMans, one of which was totally destroyed there and sent to the scrap heap.  One of these Hemi heads found its way back to Nash Engineering and that engine still exists fitted to a Nash Healey owned by Jim Walton in the USA.  The remaining head may be out there somewhere but no one seems to have any knowledge of it.

The reason the project was scrapped was the exhaust transfer rocker shafts had fracturing problems on the outboard ends of #1 and 6  cylinders because of the lack of a support tower on each side of the rocker.  The failure to make provisions for them in design was the fatal engineering mistake.  The engines were stated to make 198 HP and were very competitive at Le Mans but did not have the durability to last the 24 hours.  The current version of the engine with some modifications now makes an honest 328 horsepower.  The Ambassador inline 6 was nearing its end for the Nash Ambassador as was the whole Nash Healey project and the Ambassador V/8 engines to replace them for the regular passenger cars were on their were way.  None of the Nash Healey's ever received a V/8 prior to shipping to the US. 

 

[bradbury west]

For me, From an archive as well as general information point of view it would be very attractive to see a photo of the rocker gear, if possible, even by e mail if not posted here.
It was interesting that Mr Robson mentioned that the valve gear was reminiscent of the BMW action, presumably with crossover pushrods or some such mechanism. The original Healey Silverstone used the old Riley high in the block position camshaft enabling the valve actuation to be developed for the ERAs, so there might have some influence in design for the Nash engine.
It may be that I am completely off the mark, not unknown here, but it was just a thought. Those with more specialist knowledge may be able to clarify this.
Roger Lund

[Allan Lupton]

The BMW-style cross push-rod system was necessary as the engine was a development of a single camshaft pushrod engine and the same logic applies to the Nash engine. If you start from scratch, one set of pushrods can go diagonally between the cylinders to operate normal rockers - Peugeot did that for the 404 and the same principle was used on the Daimler SP250.

The most enterprising use of the cross push-rod was for a racing version of the Fiat 500 sidevalve engine! That was Giorgio Giusti's Drin-Drin Testadoro, the "testadoro" (golden head) being because of the golden look of the bronze casting. The drawing of how it worked has vanished since I saw it 8 years ago.

[Ray Bell]

Peugeot pushrods don't go between the cylinders...

From the 203 onwards to the 504 they had the rocker arrangement that gave hemi-style combustion chambers. The Chrysler 'Hemi' engines of the '50s and 1964 used the same arrangement too.

A lot might depend on how high the camshaft is in the block. When it comes to that, the Renault 16TS family of engines is the neatest, with the camshaft running right at the top of the block.

They also have the pushrod hemi arrangment, as did the Gordini-bred Renault engines.



.

Edited by Ray Bell, 25 April 2017 - 15:16.

[Allan Lupton]

Peugeot pushrods don't go between the cylinders...

From the 203 onwards to the 504 they had the rocker arrangement that gave hemi-style combustion chambers. The Chrysler 'Hemi' engines of the '50s and 1964 used the same arrangement too.

A lot might depend on how high the camshaft is in the block. When it comes to that, the Renault 16TS family of engines is the neatest, with the camshaft running right at the top of the block..

Geriatric memory failure!

The Peugeot exhaust pushrods go between the combustion chambers as the camshaft is quite high. What I'd also forgotten, if I ever knew, was that the exhaust valve is so nearly parallel to the cylinder axis.

Anyway the Nash/BMW system is the way to actuate valves at 45 degrees using a block designed for a low camshaft and parallel vertical pushrods. It seems strange that someone who was a good enough engineer to design the Nash head didn't provide enough support for the rocker shafts, if the piece that 3353u quotes is correct.

Edited by Allan Lupton, 25 April 2017 - 16:46.

[bradbury west]

OT a bit.. One adaptation of an existing push rod engine which I recall was Chris Lawrence's design for the TR engine in his Morgan for the 62 or 63 TT race. The Autocar did a write up on it at the time, I recall, but beyond that I have heard nothing of it.The design had the pushrods realigned to go at an angle onto the head. I spoke, by pure chance, some years ago to the man who did the machining for CJL and he reckoned the drawings were some of the finest he had come across.
Perhaps someone has a set of The Autocar from that period.
Roger Lund

[PJGD]

These are Figures 1 & 2 from Sampietro's patent US2744513, originally filed in the UK on May 23 1952.  As noted by 3353u, the outboard rocker shaft is not supported at the outer end whereas the other rocker shaft is.  It is also notable, as so often with 2-valve hemispherical chamber engines, that the sparking plug is well off to one side.

 

PJGD

[bradbury west]

Very many thanks. It is more or less how I imagined it. All we need now is a copy of The Autocar article on Chris Lawrence's design for the TR engines in his Morgan
Again, many thanks
Roger Lund

[AAGR]

I was much involved with 'works' TR4s in 1963 when Chris Lawrence's novel cylinder head was revealed. As I recall, he was invited to let the factory have one and assess it, but this offer was never taken up. Incidentally, I understand that it was not a success.

 

AAGR/ 

[bradbury west]

Many thanks for the reply Mr Robson
Roger Lund

[AAGR]

I have just found The Autocar description of the Lawrence-Tune cross-flow head for TR engines.

 

page 352, 23 August 1963.

 

This includes a cross-sectional drawing of the head. But - sorry - I cannot work how to scan and transmit the page ....

 

AAGR

[Ray Bell]

Digital photo in good light but not in direct sunlight...

[cooper997]

This should be the page Graham mentions.

 

 

Stephen

[bradbury west]

Stephen , many thanks for posting the article. I remember it from my youth in the magazine but have not heard about it since. I have raised the query several times over the years, to no avail, so I am especially grateful to Graham Robson for turning it up this time. I recall it as a crossflow design with unusual valve prodding, but had forgotten that the excellent Bill Blydenstein was the power behind the throne. The power output is interesting, certainly when figures of around 200bhp, I believe, are mentioned for TR engines in modern historic racing. Such is life.
Again, many thanks , esp to AAGR.
Usual disclaimers
Roger Lund

[Ray Bell]

It's very similar to the Peugeot 203 and 403 design, as are many of the pushrod 'Hemi' heads...