How could I have known that an innocent conversation about Ford Customlines would soon have me scampering down a cyber rabbit hole, to stumble on Ford’s GAA V8 engine for the very first time?
Another enthusiast at a recent Show & Shine had nodded agreement when I commented that OHV Ford Customlines seemed to be popping up a bit lately, after being scarce at classic car events for quite a while.
When a couple of other blokes joined in chatting about the once much-loved ‘Cussos’ the focus shifted toward available driveline options for bringing a mechanically weary example back to life. The basic question was whether you’d keep it original by investing in a rebuild of its 272ci Y-block motor or move on by grafting in a later Windsor or Cleveland V8.
“Why stop at a 2-valve ‘Clevo’?” said one bloke. “I’d go the whole hog and fit a decent motor. Maybe a ‘Coyote’.”
I couldn’t let that go through to the keeper, protesting that twin-overhead-cam, four-valve, electronic whizzbangery stuff is so far removed from the traditions of classic Fords, so new-millennium, that technology like that would be an odd choice to power any of the Fords we grew up with – right up there in the oddness stakes with items like ‘stylish’ 20-inch wheels.
I reminded him that it took until 1955 for Customlines to even get overhead-valve power with the Y-block V8’s introduction. He was unmoved and countered with a claim that years before the Customline era Ford’s engine-design team in Dearborn had successfully designed and produced an all-alloy, quad-cam, four-valve V8 that also featured a thoroughly modern flat-plane crank… His parting words as he moved on were: “Check it out – Ford GAA V8.”
I sat down for my first session with Dr Google convinced that ‘Coyote man’ was winding me up. During my mid-teens I could bore you with my detailed knowledge of American Fords from Model T through to Customline. I was across all the engines – ‘flathead’ fours, V8s, Lincoln V12s and OHV Y-blocks. The lot! And I had never heard of a ‘GAA V8’.
You could have knocked me down with half a brick when my first search attempt produced dozens of links confirming the B-I-G (1100ci/18-litre!) Ford V8’s existence, but on scrolling down there was chapter and verse on every imaginable aspect of its story.
Indeed it was an all-alloy, quad-cam, four-valve, 60-degree, ‘Hemi’ V8 with a flat-plane crank. To be clear, old mate was pulling my leg regarding any relevance of the GAA to repowering a Customline – its actual role was powering WWII Sherman tanks.
However, he was spot on regarding Ford having been well acquainted with cutting-edge engine design since the early-1940s, despite continuing to rely on its venerable but primitive ‘flatheads’ to power its everyday automobiles, through to the mid-1950s.
The GAA project kicked off in the late-1930s with Ford’s decision to build a better military mouse-trap – specifically a technically superior competitor to Rolls-Royce’s Merlin V12 aircraft engine.
Among many refinements, Ford’s twin-cam bucket-follower arrangement easily aced Merlin’s single-cam rocker-arm design. Plus there was the reduced weight of Ford’s flat-plane crank and the increased structural integrity of its mono-block casting.
Technically interesting was the worm-gear drive for the camshafts and an early ‘side-oiler’ set-up. However Ford badly misread the market – as well as the US military’s preference for air-cooled radial-power for aircraft, GM’s proven Allison V1710 V12 engine was a readily available alternative to the Merlin.
What the military was crying out for however was an alternative engine for its M4 Sherman tank program because supplies of the Wright R975 radial engine weren’t meeting demand.
Lopping four cylinders off its virtually production-ready V12 engine gave Ford its GAA 60-degree V8, an engine that met the spec for Sherman tank power plants. Apparently Ford went on to produce over 28,000 GAA V8s.
And here’s one for Mopar fans: an odd sidebar to my brief glimpse into the world of Sherman tank-engine options was discovering the Chrysler A57 30-cylinder engine – actually five separate trusty Chrysler flathead-sixes mounted together radially around a massive common crankcase.
Despite the fact that this amazing cast-iron power-pack was more than three times as heavy as one Ford alloy V8, and around 25 per cent down on power, it proved popular with allied forces due to its reliability. Chrysler ultimately produced close to 10,000 A57s.