Lister Drawings

This is a Gardner Injector, similar principle

I am trying to figure out how the excess fuel gets to the top outlet "to overflow". This is almost exactly as George has drawn it, except that the inlet is at -90d from where this one is.

My injector. Will it work?

I can't quite see all the detail of your injector HobbyNut. Essentially the effective area of the injector plunger is the area of the piston minus the area of the needle where it sits on it's seating.

The top of the plunger should be at atmospheric pressure which it will be if it is connected to the leak off pipe connected to the tank.

The injection pressure (I do not know George's intended pressure) for the full size engine is 90 bars (1450psi), a relatively low figure by today's standards. The fitted load for the spring is given by multiplying the injection pressure by the effective area of the plunger.

Eric

Whoops! 90 bars is 1305 psi

How do these injectors work? I can't see what lifts the valve? Or is it activated by cylinder pressure somehow?

Neil

Neil,

At the top of the body is a threaded cap and a lock nut inside which is a strong spring, the spring applies pressure to the needle which has been lapped into its seat sealing off the nozzle end, when the pump applies pressure to the oil this lifts the needle which over comes the spring and lifts it to allow the fuel to leak past and out of the holes in the nozzle body as a spray. depending what the engine builder requires determines the type of nozzle and how many holes that are in it to produce the spray to help run the engine.

Martin P

Edited By martin perman on 22/08/2013 21:55:58

Looks like it is easier to get working than the ME one

Thanks, so presumably it is the pump itself that determines the timing?

Neil

Oddly enough I managed to run out of diesel ina van yesterday (however the fuel pickup is arranged it didn't like a long, steep downhill). Fortunately I was only a few miles from the garage and my wife was following in the car. Equally fortunately, I had already found the priming pump on the fuel filter!

Yes Neil it is the pump that determines the timimg and the amount of fuel.

The spring in the injector decides the injection pressure.

Eric

Gentlemen,

The Lister engines I have played with and working for Lucas CAV I was always led to believe that the pump has to be timed to the engine, the pump determines the amount of fuel, I know from volunteering at an engine museum in Wales that they were given an Allen diesel in kit form and when they built it they found they were missing the timing disc and had a lot of trouble trying to find the optimum timing point, bit like to advanced or retarded.

Martin P

The pump is what is giving me headaches. It does not seem capable of developing any "real" pressure. With a bore of .188" and a stroke of .2" I cannot seem to get any real output of fuel.

Fuel injector pipe full size tends to be small bore thick walled, I think about 3 mm, what size of tube are you using, do you have any leakages that are stopping the pressure build up and is there air in the system.

Martin P

The pump ptston to bore clearnce has to be less than the proverbial gnat's.

I could be back leakage.

Yes you probably need to lap the piston to the bore down to 1000 grit and also make sure the non return balls are seating.

Yes its got a decompression valve.

J

Well the motor fired a few times today, with me spraying a tad of starter fluid into the intake tube, while cranking it with an electric drill.

The pump and injector need rebuilding. I think I will use steel for them this time, and the injector will be to Meeks' sketch, or similar.The pump clearances are what I would consider tight, but not nuclear precision! I am also going to rethink the pump design somewhat. I will let you all know how that goes.

I must thank you all for your help on this project, and I received a packet in the mail from a poster on here. I will document my work on that part. Thanks again.

I may try that after I build a pump that works!