Lister LR Starting problem

[steve c]

Hi
I have recently acquired a Lister LR1 750 rpm 1.5 bhp and I am having difficulty starting it. The engine turns over freely using a starting handle with the decompression lever engaged, but when I increase speed and disengage the decompresion lever to start the engine, the high compression causes the engine to suddenly stop rotating.

I have carried out the following tasks:
- Set inlet and exhaust valve clearences as per manual
- Cylinder head clearance (bump clearence) as per manual
- Fuel pump shims set as per manual

I would be greatful for any suggestions or ideas for the cause of this problem.

Thanks,

Steve

[dieselgman]

Steve,

That LR is quite small in displacement and should not be too hard to hand crank.

I would check the following:

Does the engine rotate slowly through a full 360 without any sudden mechanical resistance with decomp lever disengaged? (normal compression stroke should slowly leak off).
When trying to start engine are you the using correct method? You should crank up to speed and release decompression lever while maintaining and increasing force on the crank handle. Do not stop the cranking force until the engine fires.

dieselgman

[steve c]

Dieselman

Thanks for your rapid reply. With the decompression lever disengaged it is possible to turn the engine over with slow loss of compression and no mechanical resistance. The problem is when i try to start it i increase the engine speed, as soon as i disengage the decompression lever it is physically impossible to carry on rotating the starting handle. through the compression stroke

The valves have been re-ground, new ring set fitted and new cylinder head gasket fitted and the timing set as per handbook. Would putting another shim under the cylinder head be of any help?

Thanks
Steve

[steve c]

Dieselman

Thanks for your rapid reply. With the decompression lever disengaged it is possible to turn the engine over with slow loss of compression and no mechanical resistance. The problem is when i try to start it i increase the engine speed, as soon as i disengage the decompression lever it is physically impossible to carry on rotating the starting handle. through the compression stroke

The valves have been re-ground, new ring set fitted and new cylinder head gasket fitted and the timing set as per handbook. Would putting another shim under the cylinder head gasket to increase the cylinder head clearance,( bump clearance) be of any use,  At the moment it is set to the spec in the Manual  

Thanks
Steve

[dieselgman]

If your bump height is indeed to specification, then your chamber volume (and compression ratio) is only determined by the piston casting and depth of valve seats...

I suppose that it would be an easy trial to add more shims and see if you are able to start her up then.

dieselgman

[steve c]

Hi the cylinder head clearance is currently 0.027'' Manual says between 0.025'' & 0.028''  Plan to add another shim & see what happens if this dose not help have you any other suggestions as to what could be causing the problem

Many thanks
Steve