Greetings: I'd like to continue and add to the discussion about the Ford GAA V-8. My rod project involves building up one of these engines and putting it in a 1984 Ford F350 cab / chassis donor truck. The truck is a long wheelbase regular cab dually with 6.9 diesel and 4-speed manual trans. I am adding a 36" cut down sleeper behind the cab and then a 6' flat bed with my cargo being (3) 16-gallon polished beer kegs on cradles, which will double as extra fuel tanks. The truck is to be built up as a "driver" and not a trailer queen. My motto in building it is to keep it "Simple Yet Functional - Like a Sledgehammer." The GAA engine is 33" wide, only 3" wider than a Ford 4.6, and will fit the engine bay with 1.5" to spare on each side. If I offset the engine 1" to the right, I won't even have to move the vacuum booster. The heater box, however, will have to go. The GAA engine is only 3" longer than a Ford 300" truck 6, but will require notching the firewall for lengthwise clearance. I want to add a Detroit Locker to the Dana 70 axle. The engine requires an automatic trans, as the engine's torque cannot be controlled with a manual trans and riding the clutch. I'm starting out with a Ford 4R100 and will changeover to an Allison 6-speed after I've saved up a whole lot of pennies and dimes. On to the engine: my #1 engine as built up is stock except for carburetion and ignition. The 2 Stromberg 2-bbls have been replaced by 3 Demon 4-bbls and the very weak WW2 era ignition has been replaced by 2 MSD distributors with 6AL controllers. I will try to attach a couple of pics of the engine to this memo. The stock engine as installed in Sherman tanks had 1,000 lbs of torque or more at every rpm from just above idle to redline. If it were left totally stock, when the light turned green there'd be 1,000 lbs of torque to pull away from the light with. With the changes made, this should increase to around 1,200 lbs of torque or more. The engine is all aluminum, but "light" is relative. "Light" means around 900-950 lbs. The block itself is very light, around 200 lbs, weighing less than a 350 Chevy cast iron block. Of course, with the 5.4" bores, its like swiss cheese. Two average men can pick up a block and carry it around with no problem. However, the crank weighs around 135 lbs, each rod weighs over 6 lbs (no use quoting gram weights here) and even the pistons weigh over 5 lbs each. The cut down flywheel weighs around 100 lbs. Still, there's no more weight on the front end than there would be with a 460 or diesel with a snow plow attached. In fact its less. The heads are DOHC, 4-valves. The exhaust headers are of fabricated stainless steel and are both light and streamlined. A whole lot of air goes into and out of the GAA. With the GAA, its tough to grasp just "how 'big' is 'big?'" Its bigger than (3) Chevy 350s, bigger than (2) Dodge V-10 rams plus an additional PT Cruiser 4, bigger than 2 1/2 Chrysler 426s, etc. If someone had a built-up Boss at 550 cubes, it would only be as big as one of the cylinder banks on the GAA. If somebody had a GM 502 crate motor, you could say, "another 48 cubic inches and you'd be half as big as my Ford." And all the power is right at the bottom end where its needed for street use. How about fuel economy? My trans has a 30% overdrive, and with a converter lockup, an add-on US Gear (0r Gearvendors) 22% overdrive, a 3.54 gearset in the Dana 70, and 265/75x16 tires, the truck will pull around 1080 rpms at 60 mph. I think 5-7 mpg is reasonable, which is in line with many other street rods, especially those with tunnel rams, blowers and / or gears. Its just another Ford truck with another Ford V-8. Only more so. The truck is being built to putter around in and drive to car shows on weekends. And if I can pull this off, I'll look forward to meeting some of you folks at McDonalds (or Burger Doodle) on Friday nights.
After all these years, those engines are finally out of the closet. Where did you find it, and what do they cost? Just curious, cant afford it I'm sure. Wonderfull work, you make it seem easy, which I'm sure its not.
Don: I was just about to make the same (or nearly so) comment: After 60 years these things are finally being discovered- such a waste (of 60 years). If I remember correctly, when Jocko (of Jocko's Porting Service) originally built the car now known as the MOONEYE's, it had a GAA in it but it was replaced by an Allison. Can you just imagine the dragsters that could have been built with these monsters over the years?
Three four barrels! That should flow some decent air, hahaha. What size are the carbs? Demon carbs come in many cfm sizes. Any pics of it installed in the truck?
Holy crap...Anyone else see the blurb about this thread on jalopnik.com? I think I want one in a ww2 jeep!
I'm finished with the engine and have just started on the donor truck. The interior is gutted and the sleeper is mounted. The flat bed frame is fabricated and I'm trying to decide which way to go on the wood decking. The motor is awaiting the trans adapter, which hopefully will be done by the end of the month. I want to run the regular stock fuel tanks, I think a 19 gallon and a 16 gallon tank mounted in the frame, and an electric fuel pump to the carbs. Then have the beer keg aux tanks gravity feed down to the stock tanks. The thing with these engines is that you could find one anywhere. I found two of them at an old time tractor dealership 25 miles from my house where I previously lived in central Illinois. They'd been sitting in the back of a storage shed for years and years. After WW2, the tanks all got scrapped out, but the engines were mounted on skids and used as irrigation pumps or generators until they came due for overhauls, then either got put away, abandoned in the field, or sold for their metal content. My engines were locked up, and were sold to me "as-is." I was able to break one free fairly easily with a 4-ft pursuader bar, but the other one required drilling out two pistons until there was nothing left in the bore. Then I had to take out the sleeves because they were ruined too. The price was reasonable, roughly equivalent to "by the pound" scrap prices, but I took a big chance that I could save one or the other for rebuilding. There's no such thing as going down to the local Auto Zone or NAPA store and finding any parts for a GAA at all. It took me well over a year of networking to find barely enough parts to rebuild one engine. A couple of head gaskets from Canada, pistons from Pennsylvania, a starter ring gear and valve springs from Texas, etc. Every change from stock, such as an intake manifold or distributor adapters, requires custom fabrication. The entire oiling system had to be redone to get modern oil filters to adapt, etc. There's been many a day that I wished I was back wrenching on small block Fords. Now it appears the GAAs are coming out of the closet. An earlier posting on this website was of a rodder in Texas with an alky-injected Mustang street machine. Another guy in Denver is starting out on a Ford F250 4x4 with a GAA. And myself as well with my F350. I've heard that a few people ran these in NHRA back in the 40s and early 50s, but they were outlawed. I met a man from the LasVegas area who ran one in a 30-ft offshore racing boat, one engine driving two MerCruiser Bravo outdrives and was able to keep up with others in his class who had dual big block Chevies that had been leaned on pretty hard. His engine was stock except for (3) 750 Holleys and (2) Volkswagen distributors. He had the Holleys with the primaries and secondaries geared together, running 12 barrels at all times. That's not much variance from stock, but to run against dual big block Chevys and hold his own, he had to have a huge amount of power. He used 6" Gilmer toothed belts to run the outdrives, one per each lower unit, and once shredded a belt when he hit the throttle too hard. Top Fuel dragsters only use 3" Gilmer belts for comparison. If you will go down to your local Cummins diesel dealer and get the info brochure on the 855 with 425 hp, you will see that in 1945 the GAA had more torque at 1000 and 1100 rpm than today's current production stock specification 855. Then the 855s turbo kicks in and the torque curves start to favor the big diesel. But the point is, 60 year-old technology based on 80-octane rotgut gas and Stromberg carburetors was able to put out as much or more power than a current model big diesel at the low end. And if you would either add a turbo to the GAA or open the wastegate on the Cummins 855 so as to equalize the competition, the GAA would well hold its own, old technology or not. Using the Edelbrock catalog's formula for CFM requirements, the GAA requires 945 standard cfm @ 3000 rpms, assuming 100% volumetric efficiency. So going a little liberal on the requirements, I could've either gone with (2) Demon 750s or (3) Demon 525s. I went with the (3) smaller units because manifold runner length was going to be an issue with only two units. Talking to some old timers and tank restorers about their experiences with the GAA, it has always shown a sensitivity to manifold runner length. And not to mention that the engine just looks like its asking for that 3rd carb to set it apart from the crowd. Thanks for the interest in my project. I'm down to the donor truck bodywork and interior, plus paint and final touches. I also need to change out the F350s' twin I-beam front axle to a F450 beam axle with its 3.5" drop to give me a little stronger front end and some more clearance under the oil pan.
In answer to a question about the dimensions on the GAA that was asked earlier, the engine is 41" long, nose to tail, including the MSD distributors on the valve covers. The engine is 39 1/2" tall from the bottom of the pan to the top of the air cleaners, or 35" from the bottom of the pan to the top of the valve covers. It is 33.25" wide including the exhaust manifolds. By comparison, the Mustang Cobra 4.6 DOHC is listed by Ford as being 30" high and 30" wide. If you can shoehorn one of those into a Mustang, then you can shoehorn one of mine into a pre-97 Ford truck. Might have to cut a hole in the hood for the GAA's aircleaners at the most.
I've been searching for the biggest baddest engine to put in my 77 Crewcab and now I think I have my answer. Thanks for thee info and I can't wait to see the finished truck. dave
Hey all, this is my first post here. TankMan, I like the way you think. All I can say is, dammit, now I need to go find me a tank engine too I'd like to put one in a tube frame 31 ford tudor street rod Post some more pics on this build up !
Hi. If anyone wants there very own GAA please feel free to contact me as my museum group has two GAA core engines for sale. Thanks Dan
Thats one monster of a motor and with 1000+ ft lbs of torque will require one hell of a drive system. I hope to see more on your project in the near future.
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