In Praise of the Humble Greaves/Lombardini motors

[Diesel Dave]

I think that the Enfield factory made a good choice for the Taurus when they chose the Greaves engine.

The Greaves motor is basically a copy of the old Lombardini 6LD series engine with some subtle differences to allow it to run in tropical temperatures, (the fins are bigger).

Here's what I consider are the benefits:

No frame modifications required
Regulator controls are easily accessible
Simple construction - can be rebuilt without removing from the frame, crank included.
It's a very light unit, the 325 weighs just 40kg with it's fuel tank and pull starter included, the 435 is under 50kg.


If we think the little 325cc unit is a little underpowered then there are 360, 400 and even 435cc versions of the Lombardini motor available.

Sluggy originally had a Greaves 360cc engine, and I replaced this last year with a 400cc Lombardini engine that boosted by top speeds from 48 to 55mph.

I managed to secure another 435cc version off Ebay last week, so I spent yesterday evening taking a good look at the subtle differences - there are quite a few even though the casings are identical.

For a start this is a B1 variant designed for generator use, it's also designated as a quiet running unit so has a de-rated power output and a higher compression ratio with soft material damping inside the shrouds. The regulator has a finer control of engine speed having counterweights rather than the usual ball and moving cone type. Best of all it has an injector pump that includes a retardation notch in the pump plunger, this retards the injection when less than 1/2 'throttle', This should mean a better throttle response at low rpm, and less knock at idle.

There is a nice cast alloy sump on place of the usual pressed steel item, it should help keep the oil cooler.

Sadly there's no flywheel alternator so I'm going to need to fit one, the little 4amp one Sluggy's currently using seems to cope fine - as it's all about efficiency it makes little sense to generate huge amounts of electrical current only to vent it as heat by the regulator.

So I have a new motor for the trials bullet, I'll use the higher compression to generate more power, I have the 5 speed Enfield box ready and I'll be doubling the mounting plates to create a much more rigid and harder wearing mounting system.

There are some downsides.......

Kick starting a 20:1 compression 435cc motor is never going to be easy; so attempting this when stalled axle deep in mud down some green lane in the middle of Essex could be more than humanly possible.

The long gearbox input shaft is poor engineering, essentially you have the power being put into the unsupported end of a long shaft, I might try and put a further 'carrier' bearing behind the clutch and strengthen the inner primary case to take some of the load.

Cheers all
Dave

[Mahesh]

Well dont know about Other countries but here in india..the Greaves Lombardini is still being used in Piaggio ape diesel and The latest model vechile are being developed with all types of features to meet vechile regulations..a few of them are

1) Exhaust gas recirculation kit
2) Catalytic converter
3)the fat bulky injector is replaced by a nice low profile slim injector..now instead of 4 holes the newer injectors sport a 5 hole nozzle dont know the newer Nozzle spray hole dia... but the old is 0.25 and 0.24 and so due to this now the head design is changed now the nozzle hole is smaller in dia.
4) The Injection pump mechanism is also modified in order to reduce the Banging sound it makes...in place to the tappet cup and its spacer a neat roller adapter is used but then again the adapter is for newer models only as they modified the Engine Body a little
5) The Main Body Bushing is also improved so that if at all the body bush gets loose and starts spinning the oil flow stops so to counter it a oil groove is provided to make sure oil is supplied always no matter what

some other improvements are bigger oil pump, oil cooler can also be fitted to diesel (in Ape City CNG version) , etc..

Personally i think the first 2 features are performance hindering and the 4th and 5th features are clever Thinking but What is with the Nozzle design upgrade..??? wont increasing the holes increase the amount of fuel delivered and thus decrease mileage..???or is it just done to excess inject so that some amount of un-burnt fuel is recycled by EGR system..???? i have The engine opened but not with me at the moment they are at the garage so i MAY if i am feeling sport post some actual pictures...lol

[BertTrack]

On the 4 to 5 holes.

The amount delivered is only controlled by the fuel pump.

Widening the spray by using more holes(and smaller diameter) should allow for better spray distribution and burn etc.

[Mahesh]

yeahs that's what i have been Thinking about the injector but the fact is that in older models not only the injector was Fat and bulky its working pressure was 210ps factory and locally the working pressure for a diesel bullet was 180ps..but in these new Slim type injectors the pressure is 250ps if fitted to a autorikshaw and if fitted to a bullet the pressure is retarded to 220ps. i am giving these specs with according to the 6LD 325 and 6LD 435 The 6LD 325 is a Fixed Bore bulky injector type still available in market from greaves used for multi purpose and then we have 6LD Engine with 3 power options 360,395,435 with removable bore used for autorickshaw with all these modifications i am talking about the injector is slimmed out and pressure is 250ps...non the less in both the engines if fitted to a Bullet the Injector pressure is retarded by a good 20 or 30 ps...and also atleast 2 shims are used in Injection pump...i personally don't know nuts about these injection systems but the mechanics here say its to silence the engine of its weird operating sounds....and also let me tell you a what they do here....

1) Put a C size piston in a A size Bore if using the engine for bikes, since the clearance is soo little between the piston and bore when idealing the engine will make less noise although this does effect the bore life a little you don't want a head ache and stress the engine gives you at the end of the day with normal clearances...

2) The cam shaft naturally has some play to it and this play results in all kind of shitty noise in the engine ..this is handled by brass bush in the body and the PTO end cover and the brass bush eliminates any play whatsoever ..but be warned if the bush is cut eccentric in downwards the teeth on crank and cam will produce a Humming sound when grinding against each other

3) Rockers are so tightly adjusted its goes against the company workshop Manuel.... which calls for a small clearance between rocker and valves... and also Push rods clearance is just illegal ..lol

[tappy]

Not sure what you mean by "ps". If you mean "psi" (pounds per square inch) then those values (180, 225 etc) would be far too low for diesel injection. If it was "bar" i.e. atmospheres, then I'd expect the numbers to be about right.
Retarding the injection timing reduces "knock" at low rpms so would make an engine used in a bike much, much less rattly - this is the dominant noise, not the mechanical noise of the piston/bore and cam followers.

[Mahesh]

lol yes i was talking about PSI guess i was too lazy to type the small i.