1700cc BDR Spec.
BDA stands for Belt Driven series A. It was designed by Cosworth to be used by Ford in a high performance version of the Capri. The German V6 Capri killed that idea. However the engine was saved by the Ford Competition Department who fitted it into a Mk1 Escort - the RS1600. This was the start of a long and successful competition life.
The BDA is a belt driven DOHC, 16 valve, alloy head conversion fitted to the Ford 1600 Crossflow block. The design is classic Cosworth, that being narrow valve angle (40 degrees included), and pent roof combustion chamber. The BDA crank and pistons differ from standard Ford crossflow. The crossflow uses a 'Bowl in Piston' type piston as the combustion chamber is in the piston, not in the head. As the BDA head has a pent roof combustion chamber it uses a piston that is almost flat across the top. The cranks differ in that the front nose of a BDA is a different profile to accomodate the cam belt drive pulley.
I bought this particular engine about ten years ago in various stages of assembly from a dairy farmer who used to rally an Escort. I heard about the engine from his brother who I was working with at the time. I paid NZ$800 for it all. In hindsight it was certainly a bargan. This engine is an early iron block. Stripping it down I discovered it was reasonably standard as it still retained the original crank, pistons and cams. All bearing shells were at original size. The engine was going to be run in a Mk2 Escort but this never happened. It was going to be fitted into my Mk1 Twin Cam, but I ended up rebuilding that car's engine to a level of tune that made it seem a shame to replace it. A Seven type car seemed the next logical choice.
I was going to keep the engine standard - but the offer of some 1700cc Cosworth pistons soon changed my mind. I purchased a worn Ford 1600 Crossflow bottom end from a wrecker to use as a basis for a larger capcity BDA. This cost $50. The head was taken to Lynn Rogers Automotive to have the ports cleaned up, valve seats machined and the inlet manifold matched to the ports. It was at this stage that it was discovered that a previous owner had already gotten there first. the ports were at the maximum for the size of the standard valves. The decission was taken to fit new hardened valve seats, machine them with a profile, clean up the ports (very minor) and match the inlet manifold. The head was modified to suit the later twin hose oil return set up as per Cosworth specs. The block was machined to suit the larger Cosworth pistons. All moving/rotating parts were balanced. As a Datsun crank is going to used in this engine it was ground to standard size and matched to the bearings. The rods were shot peened. ARP high strength big end bolts were then fitted. For the remainder I plan to fit two 45mm twin choke Delloroto carbs, BD3 cams, high capacity/high pressure oil pump. Cosworth claimed 170hp, however testing proved 165hp to be more likely. I'd be very happy if the engine dynos up in the 165 - 170hp range. Time will tell.
Whilst I have the original Ford cast iron BDA crank I have decided to fit a Datsun steel crank instead. The Datsun crank is made from forged steel and can be made to fit the Ford block. This is a cheaper alternative to the 'genuine' part. The photo of the cranks show in the far left the original Ford crank, in the middle a modified Datsun crank, and at the end on the right an unmodified Datsun crank. Also shown is a Steel light weight flywheel that mates the BDA clutch and ring gear to the Datsun crank. In case you're wondering the Datsun crank cost approx $50 plusgrinding and ballancing - if you can machine it yourself..
For more information go to my page on Modifying Datsun Crankshafts. Or contact me if you want to know more.
