These photos show the installation
of a Simple Digital Systems (SDS) Electronic Fuel injection system in an Early Spitfire.
The engine is a small bearing 1296 using a few choice performance modifications.
The Intake manifold was fabricated from aluminum tubing and flat stock with the
flanges from a Mk3 twin SU intake. The throttle body is from a 1500 Honda. Timing
is provided by a crank trigger consisting of embedded magnets installed in the fan belt
pulley and a Hall Effect sensor which is controlled by the ECU located in the passenger
compartment kick panel. The firing pulse is routed through an MSD 6A Electronic
Ignition. The Distributor was used so that the mechanical tach drive could be
retained, but the mechanical and vacuum advance systems were disabled so that the ECU
could control timing.
Air is gathered through a K&M filter located in front of the Radiator
through a cold air box. Note the air temp sensor below the intake neck.
On the bottom of the manifold plenum is a port which is connected to a MAP sensor
located on the firewall. A water temp sensor is located on the water pump housing.
I used a housing that provides for two such sensors so that I could retain the
stock temp gauge.
Fuel is provided by a Universal In-line pump through the fuel rail and is regulated
at 39 psi by a Mallory 4305M regulator and returned to the tank at the top. I had to
modify a tank from a late model Spit so that I have a gravity feed outlet at the bottom
and am using the pickup outlet at the top for the return line.
The SDS controller is programmed and adjusted by a hand held controller and a fuel
mixture knob, both of which can be disconnected when the settings are attained. An
Autometer digital fuel mixture gauge monitors the fuel mixture based on a signal obtained
from a heated O2 sensor which I installed in the exhaust pipe just behind the header. |