|AAF American Armoured Foundation Tank Museum - Tank Engines - Ford GAF V8 Tank Engine
|01 Ford GAF V8 Tank Engine||02 Ford V8 Tank Engine||03 Ford V8 Tank Engine|
Number of Cylinders: V8 32 Valve Overhead Cam
Entered Service: 1944
This engine is a the same as used in the M26 Pershing US Army Tank, an example of which can be found at the Wright Museum in Wolfeboro, NH.
I originally had this motor listed as a Ford GAA Tank Engine but Bob Konradi wrote to set me straight on a few errors I originally had on the page. Bob knows the Ford GAA and GAF tank engines very well and this is what he wrote:
" The display engine you're featuring is not technically a GAA, but is a GAF engine, as used in the M26 Pershing tanks. The exhaust and intake manifolds on the engine are specific to the GAF, as is the oil pan with the engine mounts cast in. The flywheel is also specific to the GAF, which was set up for use with an automatic transmission. The actual GAA engine used a flywheel set up for use with a dual-disc manual clutch setup, as well as different carburetion, etc.
Of somewhat more interest to me is the statement made on the engine's home page that, "the engine is the same as the license-built Rolls Royce Merlin, less 4 cylinders." This is a common misperception, as both engines have a 5.4" bore and a 6" stroke. Ford in fact at one time tried to gain a production license for the Rolls Merlin engine, but could not strike a deal with that company. In fact the license was instead granted to Packard, and the Packard Merlins were the engine used in P-51 Mustangs and other aircraft. With his pride wounded due to the perceived slight by Rolls, Henry Ford vowed to build an engine of the exact same displacement, but which would be more technically advanced and with more power.
Whereas the Merlin had a split-block casting, the GAA had a one-piece block. The Merlin had SOHC cams actuating its valves via rocker followers (similar to an Allison 1710) but the GAA had DOHC cams directly actuating the valves. The Merlin's spark plugs are located on the outside of the heads, next to the exhaust ports, whereas the GAA's spark plugs are centrally located in the combustion chamber. The GAA used a patented 8-way internal gearbox in the block's snout to drive the oil and water pumps, the accessory drives, the magnetos and the cams. The cams were worm-gear driven off this gearbox. The Merlin used a conventional (for the day) setup for operating its cams and accessories.
The entire engine situation is further confused by the fact that later in WW2, Ford of England did in fact gain a production license for the Merlin, and produced 400 engines per week at a plant in Urmston, UK."
Bob also administers a Ford GAA Tank engine website which has much more info on these big overhead cam V8 engines.
Here's a video of a US Army Pershing Tank with a Ford GAA Tank engine starting up .
Another video of a Pershing Tank with a Ford V8 tank engine moving out of a garage.
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