The age-old saying goes that there ain’t no substitute for cubic inches, but lovers of Holden’s venerable homegrown bent-eight were limited in the capacity stakes until Torque-Power’s alloy Big Paw block came along. With a 9.5in deck height, raised cam tunnel and myriad other changes, the Big Paw platform permits a 4.5in stroke and 4.2in bore to nudge a theoretical 500 cubes of displacement.

First published in the April 2024 issue of Street Machine

This particular example, assembled by Flav at Micron Competition Engines in Mount Gambier, packs a 4.125in bore to arrive at 488ci. Despite having massive cubes for a small-block engine, it’s a long way from being a full-effort race package, with the customer’s brief instead calling for a torquey, street-friendly mill.

“This motor was designed for a client who wasn’t chasing huge power,” Torque-Power’s Craig Bennett says. “He wanted loads of torque – 660lb-ft-plus. On pump fuel we ended up with 684lb-ft at 4700rpm and 744hp at 6150rpm with 26 degrees of timing, and on Elf 102 it made 722lb-ft and 784hp with 29 degrees of timing.”

The Big Paw block accepts a small-block-Chev-style rotating assembly, opening up a wide range of lower-cost options. This engine sports a Scat 4.5in billet crank, Oliver 6.125in rods and custom CP pistons with 1in comp height, arriving at 12.5:1 static compression.

The camshaft is a custom Torque-Power solid-roller sporting 260/270 degrees duration, 110-degree lobe centres and .730in of valve lift. Isky Red Zone lifters and Trend 3/8in heavy-wall pushrods convey the bump to the valves via Yella Terra Platinum roller rockers.

Cylinder heads are Torque-Power TP240 alloy items wearing 2.150in inlet and 1.625in exhaust valves, with PAC springs and retainers. Head gaskets are custom Cometic items to suit the TP240 heads’ six-bolt configuration.

The inlet manifold is a Torque-Power Big Paw 4500 single-plane, topped with an APD 1150cfm Dominator carby.

The engine runs an ICE dizzy and a Melling internal oil pump, along with a custom aluminium pan. A billet March Performance accessory drive pretties up the front system, neatly packaging the alternator, water pump and a/c. With the Big Paw running a Chev front cover, it was an easy, bolt-on fit.

While the customer is yet to decide which of his Holdens will receive the monster-cube small-block, the increased deck height of the Big Paw over a factory Holden block will necessitate custom headers, with Craig suggesting that 17/8in primaries and 4in collectors would be appropriate.

The end result is a truly unique mill with huge cubes, stump-pulling torque and sound street manners that will be sure to start a conversation every time the bonnet is lifted.

NOTORIOUS B.I.G.

It might seem hard to believe, but Torque-Power’s Big Paw block was designed a quarter of a century ago! “The goal was to create the largest small-block configuration V8 in the world – 500ci,” Craig Bennett says. “Back then there were no billet cranks or belt-drive systems available to suit Holdens, so it made sense to adopt small-block-Chev-style stuff; we could go for big cubes and have a huge selection of off-the-shelf front drive systems for things like external oil pumps, but still retain key things like the Holden cylinder position and firing order.”

Compared to a factory Holden block, the Big Paw features alloy construction, 9.5in deck height, provisions for six-bolt heads, roller cam bearings in a raised tunnel, billet steel four-bolt mains caps and a mains-priority oiling system, among many other improvements. The cast-iron Little Paw block came later, and while it allows for ‘only’ 443ci of capacity, it’s a much more factory-appearing option and retains more OEM-style Holden components, and is available with either a factory 8.875in or raised 9.0in deck height.