8 Port Power

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More photos below of the work in progress

During the build up of the Mini Sprint DOK351K I managed to locate a 1071`S" engine and straight cut gearbox, which sat gathering dust under the bench. When stripped it was found that the gearbox was in very poor condition and would not be able to cope with the power output of the engine.

I wanted something different under the engine bay, first plans of a front wheel drive Corrado VR6 power unit were ruled out after much thought.

Deep down I knew `A` series power was the way to go but with 5 Ports 1380cc seemed the best route. I came up with the idea of a short stroke big bore 8 Port engine. After meeting with Mini Spares and Bill Richards Racing the project was on line to be completed for London to Brighton Mini run in May 2001.

The engine spec was drawn up and included 8 Port Head, four Amal carbs, A+ block, 1071`S` crank, `S` rods, new straight cut gear box etc.

Dad and I set about polishing the 8 Port Head, inlet and exhaust manifolds and Amal carb kit. It was all starting to happen at Bill Richards Racing, the block was bored and honed, crankshaft re-ground and balanced. The conrods were in need of some serious attention, as the 8 Port Head has a totally different cam profile. They were machined to clear the lobes on the camshaft. Piper Cams had been instructed to make the billet camshaft to Bill’s own design.

A dummy engine build took place to work out how much was needed to be skimmed from the block. Bill was working to a compression ratio of 11:1.

73.5 mm Omega pistons were lightened and balanced, sliding gudgeon pins were modified to accept nylon bushes. With over half an inch skimmed off the block and the second dummy engine build completed, compression ratios were re-checked. Bill was more than happy to find his calculations were correct! All parts were then cleaned in petrol before the final build commenced.

With the bottom end fully assembled and centre main strap fitted, attention turned to the cylinder head. Bill’s experience showed through as he is one of the leading 8 Port Engine builders in the U.K. and highly recommended by Mini Spares. With the cylinder fully worked and flowed, the Cosworth valves, Iskey springs and titanium top caps were assembled and checked. The head was fitted to the engine with the push rods and 1.5 ratio roller rockers. Because of the 8 Port Head and short stroke combination the push rods were machined down to compensate. Parts cleaned and re-assembled, the tappets were set by the Master!

Detailed attention focused on the gear box, with the casing prepared assembly could begin. All rotating parts were replaced and uprated to save on power loss. With the Mini Spares four speed gear kit in place, gear selection was checked and found to be perfect. The gear box was then lowered on to the engine, straight cut drop gears, ultra light steel flywheel, paddle, clutch and orange diaphram were assembled.

Next Amal carbs and linkages were fitted and adjusted, this proved quite a time consuming process because of the nature of the set up. Bill fitted Cosworth /BDA ignition set up and distributor advance curve was checked and adjusted. With all the ancillaries in place the engine was ready for its first run! It was bolted into the test jig, and final checks were made.

The Bill Richards Team and I crowded round in anticipation. It started on the button and sounded beautiful, a cross between Ford crossflow and a four cylinder motor bike engine. I took the engine home to start the fitting. The old 998 cc power unit had already been removed and engine bay cleaned. At first I thought the engine would be a nightmare to fit because of the carbs at the front of the engine. With the help of my Dad, best friend Benny and girlfriend Laura the engine slid in trouble free. The evenings were spent fitting the drive shafts, uprated cross drilled vented discs, radiator, oil cooler etc. When fitting the alternator, I found a shorter belt would be needed as it touched the carbs.

The engine was run in the car and 300 gentle road miles followed before the London to Brighton Mini Run. It proved to be a real head turner with crowds around the car all day! Taking home first prize in the Custom Class I was more than happy.

When the running in was completed, the car was taken to Peter Baldwin’s rolling road to be fully set up. The engine showed 135 bhp at the crank on the rollers. With 8 x 13 inch wheels, 15 bhp was lost, power at the wheels showed 110 bhp. I was very pleased with the final result.

Thanks Mini Spares and Bill Richards Racing. Watch this space for more show reports. Avon Park Raceway – quarter mile time in the 1100cc Class.