Powered by
  • WheelsWheels
  • 4X4 Australia4X4 Australia
  • Street MachineStreet Machine
  • Trade Unique CarsTrade Unique Cars

XY GT-HO Phase III: Fast Ford Falcons

By David morley | Photos Graeme Neander, 20 Nov 2016 Features

XY GT-HO Phase III: Fast Ford Falcons

It’s the most lusted-after performance car ever built in Australia.

You probably saw this coming, right? But seriously, we could not nominate any car for the top step of this particular podium other than the mighty GT-HO Phase III.

The Phase III doesn’t just represent the fast Falcon family: it is the all-time champ. The greatest ever. The One. It was an immediate sensation on its release in ’71, and it went from strength to strength until it emerged at its current unassailable position in our hearts and minds.

But why? Why is it that the Phase III is the only Australian production car ever to make it to seven figures at auction (admittedly a few years back when prices went troppo)? Why is the car instantly recognisable, even among those who weren’t born when it was roaming the streets as a brand-newie? Why is it king?

XY GT HO Phase III rearThe answer contains a lot of reasons, but even back in the day the Phase III had people wondering out loud just how crazy this whole Bathurst homologation thing could get. The government eventually answered that for us: it warned the Big Three local manufacturers that persisting with these outrageous supercars would not be a good idea. Perhaps mention was made of government fleet contracts in the same address. Whatever, the question of how far things could be pushed was answered: This far. The Phase III was as hectic as it was ever going to get.

Okay, so that played into the XY GT-HO’s hands, making it an instant last-of-the-breed kind of deal. But beyond that, 1971 was still a time when winning at Bathurst was everything to a car-maker. In fact, without the hunger to succeed at Bathurst (and flog a whole mess of GSs and Fairmonts in the process) cars like the GT-HO and its ilk wouldn’t have happened in the first place.

The rules of the day were roughly run-what-you-sold. If you didn’t have a production car with finned alloy brakes or a four-barrel carby, you didn’t have a race car with that stuff either. It’s a far cry from today where the only Falcon in a Falcon Supercar is the headlights and tail-lights. And that’s about it.

XY GT-HO Phase III engineThen there’s the Phase III’s record at Bathurst. It’s not like it didn’t have big boots to fill, either: the XW GT-HO Phase IIs of Allan Moffat and Bruce McPhee had gone one-two respectively in 70, laying down the footings of the legend. That legend reached maturity when, as the sun went down on October 3 in 1971, no fewer than five GT-HO Phase IIIs filled the top six outright places.

Moffat had triumphed again, followed by Barnes and Skelton in second, David McKay in third, John French fifth and John Goss sixth. Only Colin Bond in the HDT XU1 could split the Ford pack, finishing fourth. Twenty cars had been under the Mount Panorama lap record in qualifying, but Moffat was fastest with 2:38.9, a full three seconds ahead of John French.

Nor did the Canadian have it all his own way: a beer carton from the crowd got scooped up on to the grille of Moffat’s car, threatening to overheat the engine. It didn’t and the carton was removed at the next pit-stop. Needless to say, magic had just happened.

GT-HO badgeIt’s as a road car that the Phase III is probably most misunderstood. Some people will tell you it was the only Falcon to bear the shaker bonnet scoop. They’re wrong. Others insist that the block used four-bolt mains. It didn’t. Not that it makes any difference to the car’s status now, but the Phase III was a pretty trick piece of gear.

Here’s the skinny. For a start, only 300 Phase III GT-HOs were made (although there are only about 700 left...) and while Ford claimed only incremental improvements over the basic GT on which the HO was based, the truth is that there were a lot of differences. Ford just didn’t want to make a song and dance about them, since it already had the insurance industry pretty well spooked.

Visually, there are really only two external differences between the GT and the GT-HO. That’s the front and rear spoilers. The GT had the shaker and it had everything else bar that plastic front air-dam and the fibreglass rear wing. Inside, it was a similar story: the HO had a choke knob where the V8 badge went in the dashboard of the GT, and the decal on the glovebox of the GT-HO said GT-HO.

XY GT-HO Phase III frontUnderneath, the HO got a longer front spring to allow for the later, XA-style, upper-control arm and it had thicker sway bars at both ends. The HO borrowed the GT’s front discs but got PBR calipers, and the front splash plates were removed to help with cooling – something Ford knew the importance of from harsh experience at Bathurst.

Rear brakes for the HO were drums but slightly wider and finned, again to help with heat dissipation. Rear wheel-cylinders were also bigger. The diff centre was tougher and you could have either a normal LSD or a rather fearsome Detroit Locker that was all about Bathurst and not much else.

Like the GT, the HO got a nine-inch rear end but there were little bits and bobs added to mount things like the sway-bar rubbers. Some cars had 28-spline axles, some 31-spline, and a range of diff ratios could be specified when you placed your order.

XY GT HO bootUnlike the GT, the HO couldn’t be specified with an automatic box, so it was the four-speed Toploader or nothing. A modified version of the twin-plate clutch was used for the HO with machined steel locators replacing the cast-iron stuff of the GT, made necessary, of course, by that monster engine.

Now, if you know your Ford codes you’ll know that HO stood for Handling Option. But that was Ford deliberately skewing the emphasis, again, to placate the shiny-bums in the insurance world. In fact, the engine was extensively modified over the 351 Cleveland in the GT and while power outputs were fudged at the time and pegged at 300 horsepower, the reality is probably closer to 380 or so (call it 285kW… not bad for 1971).

The shaker might have been the same as the GT’s but the heat-riser was blanked off and air flaps removed to supply cold air all the time. Beneath was an HO-specific vacuum-secondary Holley carb measuring 780cfm and made specially for Ford. The intake manifold was hogged out for better flow and the distributor converted to mechanical (not vacuum) advance.

XY GT-HO Phase III interiorThe Cleveland’s heads were machined to take screw-in studs and pushrod guide-plates. The valves were altered for high-speed running and the valve springs were specified to suit the solid camshaft. Speaking of which, the cam was so lumpy and had so much overlap that Ford had to engineer a vacuum tank under the bonnet just so there would always be enough vacuum to power the brakes.

Naturally, the whole thing was hand assembled and balanced, and racing touches like a big harmonic balancer and a baffled sump were also part of the HO deal. Headers were a natch and blew through a twin system, and stuff like a bigger radiator was also added. Finally, a rev limiter was fitted to pull the pin at 6150rpm. It was mounted on the firewall on the passenger’s side and was famously disconnectable.

So much for the hardware. What was a GT-HO really like to drive? Well, I’ve been very lucky enough to sample the mighty Phase III myself. Yes, they’re a bit heavy to drive with no power-steer and that big clutch, but once you’re moving they’re remarkably docile. Actually, docile’s the wrong word because they’ll still buck and spit a bit if you’re lazy with the gearbox or clumsy with the clutch. But the GT-HO will cruise pretty comfortably, and when the music stops it’ll get across 400m in a mid-14. The rest of the four-door world was years catching up with that.

XY GT HO Phase III sideTypically for the day they’re pretty short-geared, which means about 3000rpm at 100km/h (depending on what diff ratio you’re running). But that only helps acceleration, which after all was the whole point of the exercise (especially since top speed wasn’t an issue with the limiter decommissioned).

When you drive a Phase III – and this is no gimme with performance cars from the ’70s – you can absolutely see what the fuss is about. Then and now.

Engine: 5763cc V8, OHV, 16v
Outputs: ‘224kW’/515Nm
Weight: 1524kg
Price: $5250

What's our fave Falcon? Check out MOTOR's take on the top 10 Fast Ford Falcons ever made here.