Lucas Mechanical PI System Model

[Roger B]

Hello Mike,

I accept that there will be some leakage, as in the full-size version, and I will feed it back to the tank. I just drilled two weep holes on the trial version to give me an idea of how much leakage there would be.  I would like to reduce the quantity to around 1/10 of what it is, so reducing the clearance from a couple of 1/100 to a couple of microns using similar techniques to my diesel injection systems.

Hello Minh,

The gear pump tests are just to measure and adjust the injector opening pressures. The shuttle metering pump will give a sharp rise and fall in pressure and the system fuel pressure is intended to be around twice the injector opening pressure as in the full-size Lucas system.

The next step is how to reduce the clearances. I made another rotor and lapped the outside which gave a diameter close to 5.99 mm. I now need to purchase a suitable reamer to give a finished bore of maybe 5.97mm so I can lap the final 0.02 mm to give 5.99 mm.

Having drilled the ports I then ran the 1.95 mm drill through the bore again to remove the burrs followed by the 1.95 mm reamer. The 1.95 mm and 1.96 mm pin gauges both pass through so I need to start lapping in the direction of 1.98 mm. This is always a little problematic as you have to lap out 0.01 mm before the next size pin gauge will enter.

[Roger B]

I now needed to look at the nominal 6mm bore between the rotor and the sleeve. I took a trial length of 12 mm silver steel and drilled it 3 mm then 5.9 mm. My dial calliper registered between 5.90 and 5.94 mm so as expected the hole was oversize and oval.

I then reamed it to 5.95 mm using the floating reamer holder. The 5.96 mm pin gauge would not enter but the 6 mm barrel lap would pass through.

I then started lapping, using 5 micron paste, and the 5.96 mm would quickly enter. On with the lapping