SILVER LINING

JOHN MAWHINNEY WAS DEVASTATED WHEN HE HAD TO SELL HIS HK MONARO, BUT FORTUNATELY HIS MATE BRETT ARMSTRONG LAID DOWN THE PINEAPPLES FOR IT AND IS NOW LAYING DOWN QUARTERS

An HK GTS Monaro that kicks arse on the dyno, in Summernats judging and at Drag Challenge

BRETT Armstrong is well known to Street Machine, with his HK Monaro earning a swag of tinware at Summernats 32, followed by a strong showing at Drag Challenge Weekend 2019. Brett bought the car just six months before Summernats, taking the reins from previous owner and builder John Mawhinney (whose 1000hp blown ’57 Chev we featured in September 2015). John had just run a sub-nine pass in the HK despite suffering a misfire, but the bonnet had flipped open, damaging the engine bay and roof (see breakout, p. 46).

Brett wasted no time getting the damage sorted. “I got a steel bonnet for it and fixed the paint,” he says. “But the miss was still there. We weren’t 100 per cent sure if the engine was hurt. I was just hoping it was an electrical fault or something.” About six weeks out from Summernats, a leakdown test saw two cylinders a fair way down on compression, so Brett ordered eight pistons from the US and madly scrambled to have them installed before the Christmas knock-off.

Astoundingly, Brett didn’t even have time to dyno the rebuilt motor before heading off to Canberra: “We just did a few laps and didn’t give it a hard time.” The hard time was instead saved for the Summernats Horsepower Heroes dyno comp.

“We were the last car to qualify on Friday and rolled 939hp; a bit more than I was expecting. We went out that night and celebrated pretty heavy,” Brett laughs.

The next day, the Monaro yielded a stonking 962 horses at the hubs, around 150 more than the next-best competitor in the Eight-cylinder Naturally Aspirated class. Even better, the HK was also crowned Tuff Street Champion!

With his successful Summernats campaign over, Brett pressed PROHK into drag racing duties after the ‘quick freshen-up’ on his Nova went overtime. “I’ve been racing the Kenda Drag Radial Series for a long time in various cars, so I thought: ‘Let’s race it and see what it does,’” he says. PROHK ran pretty sweet over the eighthmile, delivering a 5.62 first time out.

Not one to shy away from a lark, Brett decided to level-up and attack Street Machine Drag Challenge Weekend, making the call only a month out from the event. “My mate Scott Cortina had to make a custom towbar to clear the exhaust, and also put his hand up to be my wingman,” says Brett. Jai Schluter modified a trailer to suit the purpose and tagged along, with Scott’s brother Paul completing PROHK’S support team.

“Before we left, we pulled the rocker gear off to re-tension the cylinder heads and found that it had a broken spring,” Brett says. “We only had two weeks to get that sorted; we ordered a set on the Saturday, they arrived Tuesday week, then we fitted them up and the following weekend we were racing.”

The team’s first DCW pass at Willowbank netted an 8.82@155mph, a PB for the Monaro’s quarter-mile terminal speed. “A new diff centre from Western Suburbs Differential probably helped,” Brett says. “Going from a 3.7:1 to 3.5 doesn’t sound like much, but it makes the difference over the quarter.”

The PB was cause for celebration, but Brett had concerns about the ongoing issue of the misfire. “Jai and Scotty were checking over the car, revving me up to go again as the rain was looming,” he says. “We did an 8.78@150mph, this time Pbing the quarter-mile.”

Despite that success, the Monaro had a habit of melting plugs on big runs, an issue connected to the misfire and not one they’d been able to resolve. “It was only later I saw that I’d melted a plug on the first pass,” Brett says. “Jai and Scotty had pulled the sparkplugs and replaced them with fresh ones without telling me.” At that point, Brett got a bit emotional. “I didn’t drive 400 kays to hurt the motor.”

Brett hit up carb guru Ray Edwards, who was spannering for Al Vella, and explained his issue. “It was no problem for Ray; he came over and changed a few things in the carby, giving us about 15 per cent more fuel volume. I’d been about ready to throw in the towel and trailer it home.”

But while there were some issues on the track, the Monaro’s road manners were exemplary. “I’d never driven it more than 60km/h outside of a race track,” Brett admits. “It was really bloody well-mannered, ran cool and didn’t give any trouble.” Despite the stress of getting the car

THE MONARO YIELDED A STONKING 962 HORSES AT THE HUBS AT SUMMERNATS 32 HORSEPOWER HEROES. EVEN BETTER, THE HK WAS ALSO CROWNED TUFF STREET CHAMPION

ready and racing, Brett grew to love the Drag Challenge concept. “It’s just a great experience – likeminded people cruising around, filling Eskys, talking shit and going racing.”

However, Brett’s on-track woes were about to return in bum-puckering fashion. While prepping the car for the Day Two eighth-mile pass at Warwick Dragway, the team forgot to empty the oil breather vacuum pump overflow. “I hit the parachute, then the brakes and the catch can pissed all the oil and water out onto the front wheel,” Brett says. “The left-front locked up, dragging me into the left lane. I got back off it, back on it, locked up again, but kept it off the walls. I overshot the return road and had to back up the drag strip. We had considered not fitting the parachute; lucky we did.”

Finishing Day Two in fifth outright, Brett’s focus was on chasing Al Vella’s Capri. “We were only about a 15th of a second behind him at that point. I think we were the first lot to really put some pressure on him in the Pacemaker Radial Aspirated class.”

Heading back to Willowback later that day, Brett’s easy run on the road stages came to an end. “The road through the back of Stanthorpe was completely shit. I was dodging potholes and Skippys both alive and dead,” he explains, deadpan. “Coming out of Inglewood, the engine made a critical noise.”

The mandrel had spun out from the crank, hitting on the radiator. “We got her fixed up, but only got 20 metres before the front suspension started making a racket.” Diagnosing that a bolt had loosened off and was catching on the back of the hub, Jai got up under there and sorted it out. “I blame that bloody road in Stanthorpe,” Brett laughs.

Despite the car practically shaking itself apart on crummy roads and Brett almost collecting the mother of all kangaroos just outside Willowbank, the team’s woes were finally over. “We ran an 8.70, then took the exhaust off and ran an 8.63,” Brett says. “We checked everything and it was fine, but with the brakes and suspension issues, I was happy to pack up at that point. We’d had a good weekend and I was mindful not to bin it chasing Al.” Brett had one more run in him though, Pbing again with another 8.63 pass and placing himself in sixth Outright and second behind Al in Pacemaker Radial Aspirated.

Brett and the Monaro had a great time together, but unlike John who originally built it, Brett has other automotive desires. “There’s a lot of money sitting there if I want to chase my own dreams. I want to finish my twin-turbo LSX HQ Monaro, plus I’ve got an Lsa-powered HG wagon, a restored HG Monaro 350 and my Nova,” he says. “There’s always something rolling.”

It seems that Brett may consider moving the Monaro on. “I’m sure John’s happy that the car has really got out there and didn’t become a garage ornament,” he says. “But if I do keep it, I need to tune it up better and have another crack at old Al Vella!"

I HIT THE PARACHUTE, THEN THE BRAKES AND THE CATCH CAN PISSED ALL THE OIL AND WATER OUT ONTO THE FRONT WHEEL. THE LEFT-FRONT LOCKED UP, DRAGGING ME INTO THE LEFT LANE

INTERIOR: While at Elite Street Restorations under John’s ownership, factory renovations saw some roofing equipment land on the Monaro’s Silver Mink hardtop. Cue a full resto, including a Goya Red interior from Winner Products and new dash from Mark Good. Geoff from Classic Gauge Restoration reworked the factory gauges with Auto Meter innards

ENGINE: The Brodix alloy big-block displaces a chunky 615ci and is capped with a pair of Brodix SR20 heads. The chambers are fed by a Mark Sullens-built Holley Dominator four-barrel carb, and the mixture is popped by CP Custom pistons on a Callies Magnum crank. The result is a verified 962 horses at the hubs. “It’s essentially a Pro Stock motor; big pressure, big cubes and a four-barrel on E85,” Brett says

Brett entered PROHK into Tuff Street at Summernats 32, netting trophies for Tuff Street Champion, Best Street Tuff and Engineering Excellence – Street Tuff, before jumping onto the dyno and taking out the win for Eight-cylinder Naturally Aspirated in Horsepower Heroes. “At 962hp, it’s pretty stout for a single-carb engine without a dry sump,” Brett says. “Haltech even gave us the Dyno Test Standout Performance Trophy as well – not that I’m a trophy hunter!”

REAR END: Original owner John decided that the big Munro was going to need tubs despite the car’s GTS credentials. “There was only one rule: we weren’t touching the guard lip, as that’s sacrilege in my book,” he laughs. Moving everything inboard, John added a Race Products sheet-metal diff housing. Later, new owner Brett swapped the diff gears down from 3.7 to 3.5:1 for better gearing over the full quarter

FRONT END: “With that trick tubular-arm front end, it’s like a big go-kart,” says Brett. There isn’t much of the original HK left up front in fact, with Torana rackand-pinion steering, Afco Race springs, Santhuff double-adjustable shocks and Wilwood brakes replacing the factory stuff