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Ford 8 and 10hp, a short history.
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Joined: 03 Dec 2007
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Location: Orkney.

PostPosted: Fri Feb 03, 2017 7:42 pm    Post subject: Ford 8 and 10hp, a short history. Reply with quote

This article appeared in the MTWC magazine this month, and the author Yvon Precieux was good enough to give me permission to represent it.

Ford Sidevalve engine development and cylinder head design

Although when introduced in 1932, the Ford 8hp side valve engine was one of the most advanced power units, it is often stated by the uninitiated that the 10hp Ford 1172 cc engine was an enlargement of the 1932 8hp 933cc engine. This is incorrect as by 1934, just 2 years after the engine was introduced, the unit was strictly speaking obsolete to incorporate any discernible increase in power and further improvement in engine development.  This was mainly due to its initial block size and component parts that could not accommodate engine development further into the 8hp range and ultimately into the 10hp range. In retrospect the engine block was too narrow; the piston chambers too close for adequate coolant control to take the block into the 10hp category with its higher compression and temperature. One of the critical factors was the need to service the small end bushes and pins via the Ford factory at Dagenham, a costly practice, (1932-33 conrods were slightly longer and pins smaller) rather than through their agents and garages to service this area of the engine. Furthermore the use of a counterbalanced crankshaft was also only introduced on all 8hp units during late February 1933. The industrial manufacture of not one, but two engines of differing power ranges, had to be reflected economically and industrially and the use of the new wider 1934 Ford 10 casting mould for both 8 and 10 power units paved the way for the future development in the dual water outlet small side valve range into the 7Y and 7W units continuing with the single water outlet/chain driven E04A/E93A and finally into the 100E engines. That is why the late 8hp  engine has a head gasket no as YE 6051B whereas the 10 (CE) has the privilege of the A prefix, CE6051A, hence the landmark for all later Ford 8 and 10 engines comes not from the Model Y but from the initial development on the first 10 hp Ford 1172cc engine of 1934. For the post 1934 8 hp Y units this meant a more serviceable slightly shorter conrod from the 10hp with its meatier pin. Although initially up to late 35, the 10hp Ford engines shared the 8 sized engine starter flange of the 8hp Ford with its diminutive starter, further design improvements could still be incorporated in what was still the 1934 “10” casting with the use of a larger starter flange and starter for the 10 engine, the one water outlet, further increase in height in 1939/40 and use of a chain. This is possibly why it is so easy to recognise the 8 and 10 Ford side valve engine over a span of some 27 odd years.

The early Ford head and sump gaskets like the engine blocks may look similar but are not all the same. The early 8hp Ford cylinder heads 1932-34 do not normally show any designated Ford or Ford prefix (Y or 19E) lettering and do require different gaskets as the engine blocks and heads differ slightly in width. Also 18 mm Champion 7X spark plugs were used. The 32 engine head gasket carries, as referred to earlier, the part number Y6051 whereas the post 34 engine uses part no YE6051B to fit the wider block.  The combustion chambers in both the early Ford and Silvertop aluminium heads were manufactured heart shaped and unlike the later cylinder heads have their plugs central on the cylinder head directly over the 'heart' shaped combustion chamber. These heart shaped chambered heads (Silvertop and Ford cast iron) can only be used on the very early 8hp engines with their own associated gasket. This initial head combustion design although fine for an earlier era, (T head design) was proved to be inadequate for the newer turbulent (L head) engine technology of the thirties. The first aluminium cylinder head (Silvertop) was actually quite well made, but received a poor reputation not because of its manufacture and higher compression, but partly due to its out of date combustion design and unavailability of a proper corrosion resistant coolant, a situation that is still with aluminium automotive parts today if antifreeze is not used. With the inlet valve being not on the centre line of the heart, the fireball from the spark could not develop evenly within the heart combustion chamber possibly causing unburned fuel to enter the cylinder and hence late combustion? It is said that a few Ford cylinder heads with heart shaped combustion chambers do exist with the use of the later 14ml plugs, but I have never come across one. However the potential was there and the dealerships with Ford’s blessing introduced the 1934 Ford accessory item “Alta” 8 and 10 hp aluminium cylinder heads manufactured by the Alta Car and Engineering Co Ltd, Fullers Way Kingston By Pass Surbiton Surrey. Oddly enough less of these seem to have survived especially as they received the revised and more efficient engine combustion design with a new positioning for the 14ml spark plugs and combustion chamber, the layout of which has remained more or less the same throughout the Ford 8 and 10hp standard cylinder head range.  Illustrations show the early combustion chambers for the Silvertop and Ford heads with the central spark plugs and the later combustion chamber and spark plug position. Incidentally, the very early narrow block engines were not fitted with a timing pin in the front cover. The approved method of timing the engine was to mount a clock gauge directly over a piston via a spark plug hole. Something that could only be achieved on the very early engines.  Of note is that on an ohc engine etc, if valve spring breaks, disaster can follow. With the side-valve engine, a broken valve spring cuts down the power, but does not lead to any bent valves or shattered pistons. Similarly, the side-valve engine simply cannot be damaged by over-speeding unless of course you don’t put any oil or water in. Thus the side-valve design is unrivalled for engines which have to run unattended or under remote control, as used in driving pumps/generating sets/boats and even mechanical elephants. Finally the Ford sidevalve engine could be sleeved down to 1099cc to run in the 1100cc category using the early Y conrods and Singer 9 pistons and this was exactly done to the 1937 Le Mans entrant that survived the race carnage and came 14th, so you can forget about the GT40’s as this remarkable Ford side valve was the first Ford to compete at Le Mans.

Captions  Illustration A Top shows the early Ford 1932-34 cast iron cylinder head with its heart shaped combustion chamber front and back with the spark plugs holes at the combustion chamber. The lower part of the illustration shows the 1934 cast iron cylinder head with a revised combustion chamber with the spark plugs now set closer to the valves.

Illustration B shows the Silvertop head (noted from an earlier Morgan mag sent in by Dave ?) with the heart shaped combustion chambers and use of 18ml plugs at the heart of the combustion chamber.

Illustration C shows the top of the Silvertop head (via Dave) and its relative position re the spark plugs.


Better three than four.
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Joined: 30 Apr 2013
Posts: 2863
Location: The Somerset Levels

PostPosted: Sun Feb 05, 2017 10:18 am    Post subject: Reply with quote

Yvon has always been involved with the Sidevalve Owners Club and has a huge source of knowledge when it comes to sidevalve Fords.
1937 Ford 7w
1937 Hillman 80
1946 ERF C.I.5
1947 Hillman Minx
1955 Hillman Minx Mk8
1950 Commer R541
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Bill Fillip

Joined: 06 Apr 2017
Posts: 17

PostPosted: Thu Apr 13, 2017 10:54 pm    Post subject: Reply with quote

Yvon is very knowledgeable and friendly. We had exchanged information several years ago.
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