Lister LD & LR engine compatibility

 

Please note that this information is provided in good faith. If in doubt please check with experts before getting stuck into the oily bits! 

Operationally the LR engines can produce a greater horse power by running at higher revs., although the Auto-Truck, as far as I am aware, always used 1800 rpm. engines.

The main physical differences that I am aware of are:-

1/ The piston combustion chamber fixing was altered on the LR to prevent failures. The LR pistons will however fit the LD engine.

2/ The cylinder cooling arrangement is slightly different on the LR. The outer air deflecting plates can be removed without damage with the heads in place.

3/ The barrel fins are more square on the LR, although they appear to be interchangeable so long as the cooling ductwork is also changed.

4/ The LD head has a separate injector cooling sleeve, the combined injector and sleeve is longer than the LR's integral arrangement. LD and LR injectors do not appear to be interchangeable without swapping or machining the heads.

5/ The LD main bearings are composed of two different metals, both have machined oil grooves and oil is delivered straight into a oil hole in the bottom shell. On the LR engine both halves are made from the same material and the bottom shell has no oil groove.

Notes:

On the LR to accommodate the alteration to main bearings, the flywheel end housing is machined to allow oil to flow behind the bearing, to a oil hole in the top shell. The centre bearing is similarly machined to allow oil to flow behind the bearing, to a oil hole in the top shell. At the other end, the outer main bearing's oil hole, is drilled into the crank case at a different angle, to deliver oil directly into the top shell. The short oil delivery pipe is therefore slightly different. 

Because of these differences, LR main bearings cannot be fitted directly into a LD, without first machining the bearing housings. I can see no reason why LD bearings cannot be fitted into a LR, although you may have to drill new oil holes in the top shells.

LD bearings are however becoming scarce these days, although the centre mains still appear to be obtainable. There are specialist suppliers around who presumably bought up redundant stock, however their prices are high (e.g. 28 per journal!).

The centre bearing is similarly machined to allow oil to flow behind the bearing, to a oil hole in the top shell. In addition the  two halves of the LR have location lugs located in slightly different positions to prevent the two halves being incorrectly fitted. To fit LR centre bearings in an LD engine you must either fit an LR centre bearing housing, or machine the LD housing to accept the LR bearings, this involves machining  the housing to accept a small insert which is machined to suit the LR location lug.

 

LD & LR big end bearings appear to be compatible, however I am about to find out!

The thrust bearings on the LD and LR are still being used on the current engine range.

 

Please let me know if there are any errors, or you have anything to add! mailto:autotruck@btinternet.com