ONLINE battles between classic car purists and street machiners have raged in recent years, as the values of our favourite chrome-bumper models soar. Melbourne’s Shaun Scerri has tasted life on both sides of this fence with his ’73 HQ GTS Monaro sedan, rebuilding it to a dealer-fresh state several years ago before binning the thongslapper and M21 in favour of an 800hp blown 406ci Chev.

First published in Street Machine’s 2021 Yearbook

“Over three years, my cousin Jason and I restored the car to factory-original specs,” Shaun begins. “I drove it around like this for about six years, but I really didn’t enjoy driving it as the power didn’t excite me. So I went down the path of modifying it.”

Genuine Tangerine HQ GTS four-doors aren’t exactly dropping out of trees today, but Shaun lived the Hollywood fantasy when he found his, rescuing the more-door dirt-cheap from a scrap-metal yard way back in 2006. “It was $2500, and that was cheap for that time, but it was a complete car,” he explains. “It was in undercoat with all the factory drivetrain, and although it needed a full restoration, it was a really good starting point.

“I’ve always had a soft spot for HQs and I’ve had Monaros before this one: an HT, then an HJ coupe, and then I got this HQ sedan,” Shaun continues. The factory-style resto was something new for him, though. “Normally I’m more into performance cars,” he admits. “When I did start modifying it, Monaros weren’t worth what they are today. In the end, I built it for myself to enjoy it, and I don’t worry about what I’ll sell it for.”

Finding a bent-eight with more power than a 253 is easier than falling out of a boat and hitting water, but Shaun didn’t leave anything to chance. Matt DeSpirt at MDT Race Engines screwed together a stout 406ci mouse motor using a Dart block, Scat crank and rods, SRP blower pistons and a Comp solid-roller cam.

Up top, CNC-ported AFR alloy heads handle the atmosphere rammed in by the Blower Shop 8/71 pump, while an MSD dizzy and 7AL box light the fires. Originally, Shaun had the HQ set up with twin fours perched atop the blower, but he’s recently changed that up for an EFI set-up using a FuelTech FT550 ECU.

“The carburettor-fed motor made 830hp at 10psi boost, running E85 on an engine dyno, and I haven’t had it back to the dyno to stand on it,” Shaun says. “It’s making 13psi with the injected set-up, so I’d expect to see decent numbers. I’ve been to a few Summernats, and a blown, injected small-block is the toughest; I just love that style, as I’m a little bit old-school.”

A manualised Turbo 400 and Dominator 3500rpm converter live behind the angry Gen 1 Chev, with a stout nine-inch out back packed with billet 31-spline axles, a Truetrac centre and 3.9 gears, which will be short enough to make any freeway on-ramp serious fun.

While the noise-maker was getting its computer-controlled birthday, Shaun went over some aesthetics that needed attention after six years on the road. “I drove the car a lot, so I ended up getting the body and paint redone while it was switching over to injection,” he says. “The engine was stripped down to be blacked-out, and I deleted the heater box to make the engine bay neater and colour-coded it.”

While it is making plenty of snot, Shaun sees the HQ as a street car first and foremost, so don’t expect to see him in the staging lanes anytime soon. “Maybe I’ll run a number, but it isn’t a race car,” he says. “It’s a lot of money to risk today. I actually haven’t had a chance to do much driving in it, but when I had carbs on it I used to do a lot. I love local cruising, as it wasn’t too good on the fuel; I used to get about 120km out of an 80L cell!”

Surely 800-plus horsepower will make up for knowing the names of all the servo attendants around Melbourne, mate!

SHAUN SCERRI
1973 HOLDEN HQ MONARO GTS

THANKS
My cousin Jason Morrison for all his help putting the car together; Matt Brame at Brame’s Paint & Panel; Matt DeSpirt for the killer engine combo; Andrew at Outrageous Detailing