Roppo’s Garage 424-cube XY Falcon

An XY Falcon packing a ballistic, Pro Stock-style mill that still behaves nicely on the street? Sign us up!

Photographers: Chris Thorogood

There are a thousand different ways you can build a street machine, and an equal number of ways a build can come about.

First published in the April 2022 issue of Street Machine

However, the story behind this muscle-bound Falcon is a little more unusual than most, as Peter Radish from Roppo’s Garage in Shepparton explains.

“This build actually started with the engine about 10 years ago,” he says. “Danny Selva of Selva Racing was asked to screw together a Pro Stock-style engine that could run on the street [see more, below].”

With a capacity of 424ci, the PULP 98-friendly Dart Little M V8 was built with the best of everything and rewarded Danny with 862hp and 634lb-ft on the dyno. However, it was never fitted to a car; instead it sort of ended up as a really impressive display piece!

Enter Scott Briant. Scotty’s always on the lookout for cool memorabilia and potential project cars, and this blue XY sedan popped up for sale that belonged to a mate of his. It was a roller that was missing an engine and gearbox; however, the rest was in good condition. Scott and the Roppo’s crew figured it would make the perfect home for the Selva-built engine.

The roller’s fine fettle was thanks to a comprehensive build that had taken place in Sydney in the early 2000s. It had been featured in Street Machine Fords packing a tunnel-rammed, 700hp Cleveland by Trick & Mansweto.

Once the roller was in the Roppo’s Garage work bay, the tape measure came out and it was quickly determined that the burly Ultra Pro billet heads fitted to the 424 were going to be a tight fit between the factory shock towers.

Rather than hacking them out completely, Pete Milenz went about slimming the towers down. He’s done such a good job that only the most ardent FoMoCo trainspotter would notice they’ve been surgically altered.

With the extra room, Luke Lingard was able to build a set of custom pipes. They start with 17/8-inch primaries that step up to two inches before dumping into three-inch collectors, and from there it’s twin three-inch pipes all the way to the back.

Mind you, slimming the towers did require repainting the engine bay. The exterior paint was so good that the boys didn’t really want to repaint the car, so a lot of effort went into colour-matching the custom blue, which they’re led to believe was originally based on Porsche Zenith Blue Metallic.

The dry-sump pump did not play well with the Falcon’s chassis or upgraded cooling system. With the understanding that the finished sedan was to be predominantly a ballsy streeter that would only occasionally venture down the quarter, the dry sump system was swapped out for a well-baffled Moroso wet sump.

When the team started discussing a gearbox for the XY, it turned out that it had already been sorted. Upon opening the wooden crate stored near the engine, they discovered a Performance Automatic Super Comp C9 rated to 1000hp. “We all thought, ‘That’ll do the trick,’” says Peter. “It’s a really good ’box that shifts really nicely.”

Gear selection is via a B&M Magnum Grip shifter, while an SFI-certified, JW Ultra bellhousing connects it to the motor. Connection in the other direction is via a 3.5-inch thick-wall tailshaft.

As well as a rollcage, chassis connectors and tubs, the XY also came with a pretty decent rear end. This included a nine-inch with a Strange case, 35-spline axles, full spool, 4.11:1 gears, Strange billet yoke and 5 /8-inch wheel studs. The uprated leaf-spring suspension had also been fitted with traction bars.

The car had previously run low 10s, so the whole rear was pretty much left alone. It was a different story with the stoppers, though; they were upgraded with DBA rotors, along with four-piston front and two-piston rear PBR calipers. The Wilwood master cylinder is a ‘booster delete’ set-up from The Rod Shop.

To keep the build time to a minimum, the decision was made to leave the existing beige leather interior intact; however, there has been talk of swapping it out for a factory-style trim in the future.

Peter did spend a good bit of time disassembling a set of Auto Meter gauges so they could be mounted in behind the factory-style lenses in the reproduction XY GT dash.

With the rollcage blocking access to the ignition switch’s original location, it was relocated to the dash in the place previously occupied by the factory cigarette lighter.

Another big change was the wheels. After the team had looked at loads of different styles, it was a case of out with the bling and in with the black RC Comp Torx rims. These drag-style beauties measure 17×4.5 at the steering end and 15×10 out back. They’re secured with 12-point, 7075 billet-alloy RC Comp wheel nuts.

The switch to black wheels prompted the change from the existing reflective white side stripes to black. And while the paint was in great condition, Cam Creswell worked his detailing and polishing magic to get the engine bay and exterior looking absolutely stunning for Street Machine’s photoshoot.

With nearly 900 horses between the XY’s front rails, the boys couldn’t resist the urge to head down to Heathcote to see what it was good for – in spite of it being far from optimised for the track. “We’d only just finished the car; that was the first long drive we took it on,” Peter says. “While it did run 10.80@133mph, it can definitely do better. The engine’s built to rev past 8000rpm, but we only had a 6000 chip for the 6AL with us. If we tune the suspension and add a looser converter to let the engine rev, there’s easily a low 10 in it – maybe even better.”

Swapping out the 6K rev limiter is a must, and, with the team talking about doing Drag Challenge next year, the rest of the track-tuning mods just might get the nod as well. But for now, it’s going to remain pretty much as-is, as it’s an absolute blast on the street!


With a redline north of 11,000rpm and compression in the 14-point-something range, it’s nigh on impossible to run a full-house Pro Stock engine on the street. But that didn’t mean the mill in this XY couldn’t still look the part.

“The idea was to make this engine look as much like a real Pro Stock mill as possible, but be streetable,” says Danny Selva from Selva Racing. “We had to pull a fair bit of comp out of it, run a smaller cam and drop the redline back down to 8000rpm. We stayed with the Ultra Pro billet heads, Jesel belt drive and billet Wilson intake manifold, but changed the carbies to something more for the street.”

Another area that needed attention was the addition of water jackets to the Ultra Pro heads. “A lot of billet head manufacturers just bore longitudinal holes, with intersecting cross-drilled holes in the head for coolant flow and plugs sealing the bore holes,” says Danny. “Ultra Pro has put a lot of research into getting proper coolant flow. They mill deep pockets into the head, especially under the intake and exhaust valves, and then weld plates back over the voids to seal it all up. The head is then re-CNC machined. It’s quite elaborate, but very effective.”

So how streetable is the combo? “The cam is big, but it’s still really driveable,” Peter says. “With three pumps, it fires straight up and idles great!”


Paint: PPG Porsche Zenith Blue Metallic
Brand: Dart Little M 424ci 
Inlet manifold: Wilson billet CNC tunnel ram
Carbs: Twin 1050cfm BRE Dominators
Heads: Ultra Pro billet
Camshaft: Bullet .710in lift, [email protected] duration
Pistons: CP
Rods: Oliver
Crank: Bryant
Sump: Moroso
Fuel system: MagnaFuel 500
Cooling: Aussie Desert Cooler radiator, twin 12in fans
Exhaust: Custom 17/8in headers stepped to 2in, 3in collectors, 3in twin system,
Redback mufflers
Ignition: MSD 6AL, crank trigger, HVC coil
Gearbox: Performance Automatic C9, reverse-pattern, full manual and transbrake
Converter: Dominator 5400rpm
Trans cooler: PWR
Tailshaft: 3.5in thick-wall, Sonnax yoke, Spicer unis
Diff: 9in, Strange centre, 35-spline, spool, 4.11:1 gears
Front: King springs, Pedders 90/10 shocks
Rear: King lowered leaf springs, Pedders shocks
Brakes: DBA discs and PBR calipers (f & r), Wilwood master cylinder
Rims: RC Comp Torx; 17×4.5 (f), 15×10 (r)
Rubber: M&H Racemaster 185/55R17 (f), Mickey Thompson 28×11.5×15 (r)

Peter Radish, Scott Briant, Pete Milenz and Cam Creswell (Roppo’s Garage); Luke Lingard