ARDEN 8-PORT LARGE VALVE CYLINDER HEAD

Overview

The Arden eight-port offers the ultimate performance upgrade for the A-Series engine, converting from the siamese inlet port design of the original five-port head to a crossflow setup. Although excellent gas flow and overall power can be achieved from a full-race five-port, the upgrade to a crossflow design removes the scavenging problems associated with shared inlet ports.

This allows for a more consistant fuel/air mixture across all four cylinders, while straighter inlet tracts, large ports and race valves all help to unleash more power. Using aluminium also reduces overall weight and greatly improves heat dissipation compared with a regular cast iron cylinder head.

History

The Arden eight-port head was originally developed in the mid '60s by Jim Whitehouse for Works-supported race Minis with 970 Cooper S engines. These cars ran cutting-edge mechanical fuel injection systems and heavily-worked internals to achieve huge power outputs for the time. 

Competition proven, the heads were adopted into BMC's Special Tuning parts catalogue from '67, opening the doors for privateer drivers and teams into the 1970s. With the demise of Abingdon's Special Tuning department, the supply of Arden eight-ports dried up for many years, the A-Series no longer at the forefront of motorsport developments. 

We've gone full circle since then, and with the ever-increasing appeal of historic race tuning for the A-Series, the Arden eight-port head has been revived and recast, now machined with the very latest CNC equipment.  

In line with demand, the design has been tweaked for use on 1275-based engines, with larger 21cc chambers. With a carefully built bottom end and modern fuel injection system, maximum outputs of well over 150bhp are possible.

Engine requirements

This head is not a direct bolt-on upgrade, requiring a different design of camshaft, rockers, steel conrods, longer pushrods and different inlet and exhaust manifolds. Therefore the engine build should be based around using the Arden head, for which we keep all of the parts in stock, including a range of Piper camshafts.

The altered valve order means that steel conrods will be required for cam lobe clearance. For the race head specifically, we would recommend a minimum bore size of +0.040-inch for decent valve clearance.

For full-race engines we would highly recommend the use of a steel crankshaft package, four-bolt steel main caps and an MED dog-engagement gear set.

Fueling

We keep two different lengths of inlet manifold for mounting Weber 45DCOE carburettors up front, although fitment to a regular round nose Mini is not possible without modifications to the bonnet and bonnet slam panel. A Clubman front end allows more breathing space and you will be able to just about install twin Webers on a short inlet manifold with air filter.

Fitment is made far easier with an upgrade to fuel injection. Not only are the throttle bodies a more compact setup, the increased power and drivability across the entire RPM range make this the most effective option for both road and competition. The kit uses a DTA ECU and professionally made wiring loom, and whilst it does add more expense to the conversion, we would highly recommend following this route.

Road option 

We have also built many road-going engines with an Arden eight-port head. For this we can supply a cylinder head with 35.6mm inlets and 30.5mm exhausts with smaller ports to keep the gas speed up. This will still produce excellent results, with bags of mid-range torque on a rally-spec 300-duration camshaft. Please contact us for the latest pricing and availability.