4 Cylinder Triumph Spitfire
I thought you might like to see some photos of a metering unit I made up, as well as the injector body adaptors for the 4 cylinder Spitfire engine. Somewhere, I have the calibration curves and some drawings.
The metering unit used the 6 cyl rotor and shuttles and I made up a new sleeve and metering unit body. The pedestal was machined to match the 4-cyl engine hole and a new oil pump shaft was made up. It puts the distributor cap tight against the bonnet but angled leads just about clear!
I worked for Lucas in Birmingham at the time and got some info from Peter Cox (or Cook? I am not sure) and a Tony Gallier? at Lichfield Road Service. It’s all gone now, as you know. Peter gave me some drawings and Tony some parts
I used two rolling roads to play with the fuelling curves….one was Peter Baldwin’s in Cambridge UK and then later Aldon’s in Birmingham UK. We got the full load distributor curve right first and then measured CO at different loads and throttle positions. It doesn’t replicate what really happens on the road because of different drag/wind resistance but it got fairly close. I am currently on the 6th metering unit adjustment and would like to modify again slightly when I rebuild with unleaded seals from Malcolm at Prestige Developments in the UK.
We had 118bhp calculated at the flywheel at 6400 rpm from 1296cc. It has a TH5 Kent cam in……I tried one of Gareth Thomas’s higher lift TR5-profile grinds but it was very top end and there was so little vacuum at tickover the metering unit just threw the fuel in. The TR5 cam doesn’t pull much vacuum at tickover and Gareth’s was even worse…..it really needed one of those profiled mechanical cam end-plates to use such a wild cam. Over 4000rpm it really flew, but it wasn’t much fun. I have now converted the pump to a Bosch unit because the power was just flattening out at 5200/5300 rpm as the Lucas pump was failing to maintain the pressure