Harrop-blown 1964 Pontiac Bonneville

This epic Harrop-blown LS-powered ’64 Pontiac Bonneville was built by one of Street Machine’s longest serving contributors

Photographers: Ricky Rigutto

The team responsible for compiling Street Machine magazine is composed of proper, dyed-in-the-wool car guys and girls, and if you ever needed proof, look no further than our mate Iain Kelly’s ’64 Pontiac Bonneville. Iain (or Marv, as he’s affectionately known) has been part of the furniture here at SM for two whole decades, so it’s a real pleasure to bring you this yarn on his Poncho, especially knowing the hardship he had to endure to finally bring the car to fruition.

First published in the April 2023 issue of Street Machine

Marv’s life with modified cars has seen him own a rich tapestry of vehicles, ranging from rad chrome-bumpered Holdens to late-model LS-powered rockets and some weird BMWs and Subarus that we’d really rather not disclose here if it’s all the same to you.

But the Bonneville is the by far the coolest of the lot, slammed on ’bags, rolling on one-off, custom-made Mawer-inspired billets, and powered by a stonking Harrop-blown, Warspeed-built 403ci LS.

But he didn’t set out to build the car in this way. In fact, the original plan was to build a different car entirely – a ’62 Bonneville four-door hardtop.

“My ’62 was meant to be a ‘Bellflower’ custom, a style that sits between a lowrider, street machine and a custom, which is typified by the sort of cars you see in the Los Boulevardos Car Club or from Deadend magazine,” Iain explains.

The build was progressing in earnest in his backyard shed when disaster struck. An electrical fault sparked a fire that destroyed the shed and everything therein: all Iain’s tools and spares, his prized car mag collection, and, yep, the Pontiac.

Iain was quite obviously heartbroken, but once he got back on his feet, he happened upon another Bonneville to resume his Bellflower custom build. As fate would have it, he was tagged in a Facebook post by US creative Coby Gewertz, who was looking to shift this ’64 coupe. Marv promptly bought it, and it landed Down Under in February 2015.

“I knew it was a project, but it was running and driving when I got it, so I did a service, registered it and took it for a drive to Terrigal,” Iain says. “Then the transmission blew up, and you can’t get parts for the standard four-speed Super-Hydramatic auto used in these cars, so I was going to have to convert it to a TH400 from a later model.

While that was happening, I realised the engine had way too much crank end-float, so I got Peninsula Engine Service in Brookvale to rebuild the stock 389ci engine as a mild 400ci with a Comp Cam, HEI dizzy, rebuilt carb and upgraded later-model water pump. I also chose to upgrade to a 1966 GTO top end.”

In went the new powertrain along with AccuAir airbag suspension, VintageAir a/c and a disc brake conversion; then Marv stripped the body for paint. He ended up moving the rebuilt Pontiac engine and ’box on in order to pay Brad Power from Cool Az Hot Rods in Tuggerah to paint the whole car in VE Commodore Poison Ivy green, but he was then left with an empty engine bay once more.

“Around this time, I’d been putting together a spicy LS for the Mighty Car Mods boys with Troy Worsley at Warspeed. Conversations happened and that engine ended up going into my car,” Iain explains.

Said engine is a properly legit 403ci LS, topped by a Harrop TVS2650 belt-driven inlet manifold. To an LQ4 iron block, Troy duly added a Texas Speed crank and rods, Wiseco slugs and a custom Texas Speed bumpstick, offering 236/240 duration on 116 lobe centres. Heads are Texas Speed-ported LS3 castings with TSP rockers.

It’s all run by a Haltech Nexus R5 VMS and PD16 wired by Dave Forrester, with a beefy fuel system culminating in 1500cc Raceworks squirters metering either pump 98 or E85, according to the will of a Haltech flex-fuel sensor.

The engine is backed by a beefy Hughes Performance 4L80E with a Hughes 3200rpm converter, so Iain and the family can cruise in overdriven comfort. The nine-inch rear end runs a Strange iron centre, Truetrac LSD, 3.23 gears and billet 35-spline axles, and was pieced together by Geelong Diffs.

An LS-into-’64 Bonneville conversion kit doesn’t exist, but Marv used a set of universal Tuff Mounts LS engine mounts to get the mill sitting pretty in the bay, and the Pacemaker HQ Holden-to-LS conversion headers required only a gentle nudge with the persuader to work for the application. Cooling is handled by a VF GTS radiator and fans, although Marv had to carefully hack up his already-painted front end in order to fit them.

The pièce de résistance is undoubtedly the custom 17-inch Mawer-look billet wheels, inspired by Marv’s love of vintage motorsport. They measure in at 17×8 up front and 17×9 on the rear, wearing Michelin Pilot Sport 4 235/45R17 and Federal ST-1 275/40R17 hoops, respectively.

Most of the car came together in Iain parents’ garage on the NSW Central Coast. “It took ages, as I’ve got no money and am self-taught, so I stuffed up a lot!” he laughs. “Scotty Barter, Aaron Gregory and I set up the engine and trans, made the mounts and got the drivetrain sorted at the Mighty Car Mods Super Garage, but [things like the] exhaust I made myself in one 18-hour day using a 125mm cordless grinder and a MIG welder. While the welding is pretty shabby, I built it all myself, and I’m proud to say it hasn’t fallen off yet.

“Now that I’ve done most of the shakedown, I am loving actually using the car, sharing it with my family and wife and proving this expensive bunyip was actually worth all the pain, frustration and working four jobs to pay for it,” Iain continues.

“The next steps are to add a wiper motor, upgraded shocks, sway-bars, and some seatbelts and anchor points in the back so my son Arthur can come out fat-lapping with Dad.”


Paint:GM Poison Ivy green
Brand:403ci GM LQ4
Induction:Harrop TVS2650 FDFI supercharger, water-to-air intercooler, 110mm drive-by-wire throttlebody
ECU:Haltech Nexus R5
Heads:Texas Speed CNC LS3, TSP rockers
Camshaft:Custom Texas Speed, 236/240 duration, 116 lobe centres
Conrods:Texas Speed forged I-beam, 6.125in
Pistons:Wiseco forged, 10.67:1
Crank:Texas Speed forged, 4in stroke
Oil pump:Melling
Fuel system:VE Commodore lift pump, twin TI Performance external pumps, Raceworks surge tank, Raceworks lines, Haltech flex-fuel sensor, Raceworks 1500cc injectors
Cooling:VF GTS radiator and fans
Exhaust:Pacemaker HQ LS1 17/8in headers, Vibrant Performance custom oval-tube exhaust, Vibrant mufflers, 100-cell ceramic cats
Ignition:LS1 coil packs, custom leads
Gearbox:Hughes Performance 4L80E
Converter:Hughes 3200rpm
Diff:Geelong Diffs 9in, Strange iron centre, billet 35-spline axles, Truetrac LSD, 3.23:1 gears
Front:Slam Bags airbags, relocated Summit shocks
Rear:Slam Bags airbags, Summit shocks, reinforced lower four-link arms, custom United Speed Shop adjustable upper arms
Airbag system:AccuAir e-Level management, AccuAir ENDO-VT tank/valves, Viair 485C compressors
Brakes:Hoppers Stoppers vented discs and AU Falcon calipers (f), Wilwood discs and calipers (r)
Master cylinder:GM
Rims:Custom-made three-piece billet Mawer replicas; 17×8 (f), 17×9 (r)
Rubber:Michelin Pilot Sport 4 235/45R17 (f), Federal Evoluzion ST-1 275/40R17 (r)

Troy at Warspeed Industries; Dave, Luke, Richard and Scott at Haltech; Heath and Jake at Harrop; Pete Nichols; Hughes Performance; Texas Speed & Performance; Jamie at Raceworks; Aaron at Vibrant Performance Australia; Pacemaker; Jase at Tuff Mounts; Marty & MOOG at Mighty Car Mods; Brendan at Car Builders; Matty at Geelong Diffs; Mark Hooker at Barrel Bros; Martin at GT Wheels; Eric at Hoppers Stoppers; Steve at Trimlab; Ryan at United Speed Shop; Brad at Cool Az Hot Rods; Cliff Leonard at Original Parts Group; Scotty Barter at Oxytech; Aaron Gregory; Brett Williams at Willows Detail Co; Benny Neal; Ash Thorpe; Shane Jenkin; Kris Reberger; Speedy Air Spares; Ray & Meredith Kelly for letting me destroy their garage; last but not least my wife Kate, who supported me tirelessly through all the ups and downs.