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If you will send your e-mail address to me at: firstname.lastname@example.org I will e-mail you back some pics of my #1 engine. Its definitely not what the GAA looked like back in '45, but its what it looks like now. Also, some time ago I visited with a man in the LasVegas area that ran a GAA in a 30' offshore racing boat. He used one engine to run two outdrives, a stock GAA except for (3) 750 Holleys and two VW electronic distributors, and was able to keep up with boats running two big block Chevys that had been leaned on pretty hard. He never dyno'd his engine, but if you think about how much power it would take to keep up with a race boat with two Chevy big blocks, his GAA was definitely getting with the program.
Ford Motor Company thought it would be easier to produce an aircraft engine of its own design than to license-build the Rolls-Royce Merlin. A revolutionary and innovative 60° V-12 was designed and built, but before it could be fully developed, the US became involved in World War II. Ford removed four of the cylinders, resulting in a 60° V-8 for tank use that developed 450 hp @ 2,600 rpm. Several variants were produced.
The Ford GAA was used in the M4A3 (1,690), M4A3(75)W (3,071), M4A3(76)W (1,400), M4A3 (105) (500), M4A3E5 (254), M4A3(76)W (3,142), M4A3(105) HVSS (2,539), M10A1 (1,413), and M7B1 (826).
The Ford GAF powered the M26 (2,222), M26A1, and M45 (185).
The Ford GAN, powered the T23 (248) and M4A3E5 (254).
In order to meet the need for a larger engine, Ford resurrected the V-12 as the GAC, which produced 770 hp and powered the T29 (6).
I'd love to see one of the 6 GAC V-12s.
2007 F-250 Super Cab Short Bed 4x4 XLT Sport Package 5.4L 3.73LS Tow Command Stuart Retired Master Sergeant FTE Guidelines
Actually, there were 10 GACs built and installed in tanks. There were 6 M29 prototype tanks and 4 M32 prototype tanks. One was an up-armored version of a Pershing tank, and the other was a standard Pershing tank with a more powerful engine, because the V8 just didn't have enough power for the Pershing, which weighed 10+ tons more than a Sherman. So there were 10 prototype tanks with the 12. There's no record of how many spare 12-cyl engines were built. I know of two military parts wholesalers who have NOS carburetors for the 12s, so apparently there were some spares made. The Army overhaul manual for the GAA has a copy of the Ford dyno sheet, and it shows 500 hp @ 2600 rpm and 525 hp @ 2800 rpm. The overhaul manual instructs the depots to reject any rebuilt engines which do not dyno out to 475 hp.
I did talk to the military equipment collector who at one time had GAC engine #001. He had it on display with his collection. However, a fellow collector had one of the tank prototypes with the V-12, grenaded it, and prevailed on this collector to sell it to him for retrofit into his tank. I recently made a few inquiries with people who restore tanks to see if they knew of any of the GACs floating around, but nothing came of the inquiries.
In looking at the GAA cylinder heads, you can see the heritage of Ford's policy of putting severe doglegs in the exhaust. There would be a substantial power increase with raised ports. The intakes, as well, could have been much better designed. For no particular reason Ford elected to put one carburetor at each far end of the engine. Then they enclosed the intake passageways in the form of a cast-in, integral manifold. To minimize separation of the air and fuel particles, they used exhaust heat under the carbs, and cast in the hot water returns on top of the intake passageways. Despite this, the end cylinders ran very rich and the center cylinders ran lean. Nearly all used heads that I've seen have heavy carbonization in the end cylinders and valves, etc. The plugs that were used were inadequate, and often fouled. The plugs themselves were recessed in little preignition chambers which further restricted the weak spark. I'm told that each tank carried 100 spare plugs for when fouling occured. In my engine, as in all other modified engines that I've seen, the intakes are entirely revised to a contemporary design, opening the air passageways in the middle of the engine, plugging the ends, and putting the carbs (or blowers) right in the middle where they belong. It is my firm belief that there is 150 hp or more in just revising the intake side of the engine. I also think there is 50-100 hp in the ignition system, using MSDs with 6AL controllers. Opening up the precombustion area and using 14mm x .750 reach plugs now puts the spark right where it needs to be. You have to see the before and after to see where the HP improvement numbers come from. I think I'm realistic in projecting 250+ HP to be gained in updating to a modern standard, including using 89 octane ethanol instead of the 80 octane rotgut available in 1945. Far future plans include building a #2 engine with dual 460 throttle body EFI, (2) 30 or 36-lb injectors per cylinder and a Ford EEC-IV controller.
Changing the head gasket on our 1978 Ford grain truck with a 534. The head gasket was cracked from the front water jacket to the front of the head/block. Does anyone know the head bolt torque specs and the recommended valve lash on the 401/477/534 super duty engines?
366 and 427 Chev's were "tall deck" engines. The cylinder block was o.400 inches taller than the 9.8" LT and car big blocks. The tall deck was 10.2 inches. The 427 tall was a good engine and made a lot of power. The 366 was very powerful, but only hit about 4000 RPM. It can just sit at that all day.
I worked for Duthler Ford (car and truck), in Grand Rapids MI, from 1969 to 1976. We bought new (FT) 391 and 534's from the local Cat. dealer, and delivered them to (mostly) West Michigan county road "commissions". They were probably (mostly) replacements for dump trucks, and came with a 100,000 mile warrenty from Ford.
They were industrial versions, on skids, and complete with bellhousing and double disc clutches (on the 534 for sure).
For some reason, we could buy them cheaper from the Cat. dealer than directly from Ford (probably a volume purchase thing).
Gee, somebody seems to have forgotten the Continental built (I think, but it may have been IHC) RD602 602ci inline 6. We had them in our M54 trucks (Truck, Cargo, 5Ton, 6X6 was the official nomenclature) They had a Holley 885JJSG 2 barrel that gave us roughly 3 mpg. The wrecker was a Holmes 850 twin boom on an M40 chassis (same chassis, but no bed or box, just the cab) It got 2 mpg empty and 1 mpg towing. I seem to recall the redline was 3500 rpm, but there was a warning label not to exceed 3200 or the clutch could explode. I don't have the HP/Torque ratings handy, but it was a stump puller from what I remember.
Bill Vose (Old School Hot Rodder) 1986 F350 crew cab DRW 460ci EEC-V MAF/SEFI, E4OD, PMGR starter, 160 amp 3G alternator, 12X3 1/2 rear brakes, Traction lock 3.55
1995 Lincoln Continental (project car), 1994 Taurus LX (daily driver) http://www.oldschoolhotrodder.com
"growing old is inevitable, growing up is optional"
Caterpillar offered a series of medium duty diesel v8 engines in the mid 60's. They were the 3000 series. (later 3208) Ford was the first to use these diesel engines (exclusively for a year or more) and were called the 1100 series in the Ford trucks. Some people said that they were a modification of the 534 block, but this was not true . They were designed and built by Caterpillar.They had no sleeves but were of parent bore like the 534 and overall were about the same size as the 534. The earlier models were naturally aspirated, ratings were in the 225 horsepower range.
Later Caterpillar made turbocharged marine versions of these engines with ratings close to 500 horsepower.
Last edited by royster; 05-01-2007 at 02:26 PM.
The comapny I work for had a few GMC C-6500 5 yd. dumps with 427's in them, backed by a 5 speed and a 2 speed rear axle. They ran very well, even pulling a backhoe on a trailer. Very thisty! It's all in how they are geared. As for the Ford GAA tank engine, I don't know too much about them, but I read where they weren't really a Ford design. They were a cut down Rolls-Royce Merlin aircraft engine.
The Ford GAA was a Ford designed V8 engine. Ford was asked by the US government to manufacture the V12 Rolls Royce Merlin engine, but instead decided to design their own engine. The confusion might be because it was the same 5.4 inch bore as the RR, but was a completely different engine. It is all aluminum with steel sleeves , gear driven dual overhead cam design. 4 valves per cylinder .THe V12 version came first therefore it is a 60 degree engine. It was only built in small numbers ,The V8 version came later known as the GAA engine. It was built in large numbers and powered many US army tanks, The GAA had 1100 cubic inches and developed 500 horsepower.
One thing most people are missing about the 401-534 series and its limited performance is the poor combustion chamber that the "planked" head gives relative to a better quench-style.
The surface to volume ratio of this style of engine is off the chart in the wrong direction, even though there is functionally no chamber to speak of.
If there is an upside, you can sneak a pretty big valve in there and the only problem is hitting the bore itself. Problem is that it stops breathing about 6000 (not a problem in a truck, techincally) because the incoming charge hits the cylinder wall instead of tumbling, swirling or dispersing itself.
The heat does everything but work in this engine, there is soooo much area when the piston comes up to the top of the stroke. Chevy 348-409-427 (early) Truck motors and the MEL Fords had this same configuration, and all were discontinued for pretty much the same reason and replaced by nearly identical engines (BBC/385 Ford)
The Ford exhaust port dogleg is almost always a function of having to put the engine in a chassis or package it was never designed to accomodate. The 429 got its port bent to fit the Torino/Mustang unit body; ditto the 335-series.
And the genesis of the GAA was an aircraft, not a cramped Sherman tank, so I'm sure that if the engine had been produced in its original concept, the output numbers would have been dramatically higher with a cleaner raised exhaust port, forced induction and eventually fuel injection for inverted mounting or acrobatic flight. All the liquid cooled multi-cylinder 12's had that by '42-3 including Allisons and Merlins.
I have an engine that I am not sure what it is, other than being a big block ford. It is gray in color, and has heads with four center bosses that I think the valve covers bolt to, as there are no bosses on the outside edge of the heads for them to bolt to. it has a timing chain and gears flattop pistons, two valves per cyclinder, and alot of the parts end with AA.
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