[Big D]

Hi all,

Today I spent some time looking over the various Hercules JXD engines I have for both the M8 and the White Scout car I am restoring.

My engine reconditioner has had two Hercules engines at his workshop for me for several years (that’s another story). Well, he has now started work on the job of getting one engine rebuilt for my Scout Car so it was a good chance to take stock of what I have and what engines I could put together.

As I say, I have two engines for the scout car with the engine reconditioner. I also have three partly complete engines for the M8 at the workshop. I’d like to know exactly what parts on these engines are interchangeable between the M8 and the Scout Car.

From what I understand, the short blocks on these are the same. That is, the short block on an M8 will be fine for a Scout Car and vice versa. I know there are differences with the clutches, waterpump, gearbox and oil pump where these parts are not interchangeable. What else is there that is different?

Of the two engines at the reconditioners; one has a good block and had .40 thou pistons in it. This block has now been crack tested and it appears fine. It also looks like the bores and pistons will be okay with new rings.

The other block had the pistons completely stuck in the bores. Several pistons got broken in the process of getting them out. The bores look bad but the walls themselves appear fine and have not collapsed at all that I can see so far.

The three engines for the M8 in the workshop all have the pistons stuck in the bores, as per the photos. All have a wall in the bore that has collapsed. I understand that sleeving these bores is an option providing that there is an inch at the bottom and an inch at the top that is sound which will support the sleeve. Has anyone else had experience with sleeving these with such a scenario?

So, can I mix and match the blocks between the M8 and the scout car? What other parts can I mix and match and still end up with a correct M8 engine/Scout car engine. What other differences do I need to consider?

I have spare valves, STD pistons, 0.20 thou pistons and 0.60 pistons, plus spare valves and as you can see three spare crankshafts. I also have mains and big end and camshaft bearings. These bearings are all readily available anyway.

My ideal scenario is to build a good engine for the scout car, a good engine for the M8 and have a spare engine that I could potentially use in a future project.

Any thoughts or experiences with the Hercules JXD engines would be appreciated.