[Big D]

Hi all,

I’m looking for some advice on the Hercules engines for the M8/M20 armoured cars and whether the resident experts have experience with the JXLD engines as opposed to the JXD. I see some have fitted JXLD engines to M8/M20’s but I was wondering whether they were left in stock condition or whether they were ‘made to look’ like a JXD setup.

I need to put another Hercules engine together for an M20. I have several JXD blocks here but all require lots of work including removing stuck pistons and machining/sleeving the bores. Some blocks have holes in the bores so I don’t even know if they are viable options yet. I have plenty of pistons, rings, valves, bearings etc and providing one of the blocks is suitable, I could put something together. I have carburettors, fuel pumps, manifold etc but would need a timing cover, sump and a few other bits and pieces.

The other option I have is a Hercules JXLD engine which was in the M20 I have here. I’m guessing that this M20 was retrofitted with the JXLD when it was in the hands of the Greeks. I still need to investigate the internals of the engine but it is certainly in complete condition and has the required timing cover and mounts.

I understand the JXD and JXLD short blocks are similar, with the JXLD having a longer stroke and the external parts located differently on the block. There seems to be a lot of similarities and the timing cover, head and starter motor setup appear the same as the JXD. I understand the M8 manifold is a bolt on and the generator mount is the same as the M8.

The JXLD water pump and distributor/coil assembly is different to the M8/M20 JXD setup. The fuel pump is located on the other side of the block which pushes the oil filler/breather to a different location.

Subject what I find internally with the JXLD, what I have in mind is to make it look like a JXD as much as is possible and fit it to the vehicle. I can rebuild the other JXD blocks at a later time when finances allow it a bit more.

Has anyone tried to move the fuel pump on the JXLD to the other side, like the JXD? This would allow the breather/filler to be moved to the spot the fuel pump is currently located. Alternatively, I could just leave the fuel pump where it is without losing too much.

From what I can see I could fit a JXD water pump which would provide the right angle for the JXD distributor.

Has anyone tried to do this? What other hurdles are there?