[Big D]

Hi all,

Thanks to Willy, who is a fountain of knowledge on M8’s, Scout Cars and anything armour, I’ve worked out the differences in the engines on the M8/M20 and the Scout Car. The basic engine blocks are identical and have interchangeable crankshafts, camshafts, valves etc. The parts that are different are all the extras:

• Oil pan and oil pump
• Bell housing and timing cover
• Flywheel and clutch assembly
• Starter motor, water pipe and distributor

The reason I was keen to know this was to make best use of all the Hercules engine parts I have. I have a spare engine block from my scour car restoration which now has all the pistons out of it. The bores on this are worn, but are sound with no damage to the walls.

The three engine blocks I had for the M8 all have stuck pistons with damage to the bore walls. After comparing the spare scout car engine block with the three M8 engine blocks, I’ve decided that the scout car block is the better candidate for a rebuild for the M8, so I will use that one. I’ll remove the timing cover, bellhousing, sump etc from the M8 blocks and use those on it. I will work out what combination of pistons and sleeves etc I will use at a later time, but it was just good timing to be able to check this while the scout car engine was getting rebuilt. By the looks of things, I should have enough bits and pieces to rebuild at least two more Hercules engines on top of these two, but that will be something I will sort out later. The Hercules block and head being machined in the photos are for the scout car.

Thanks also to Willy for his recommendation on trying the rubber shock bushes for the Dodge M43. I’ve found these are a better fit than what I had. The ends still need cutting down a bit though so that they fit in the 1.75” gap in the shock absorber mounts. I used a hacksaw to do this and then smoothed the ends with a flap disc on a grinder. This gives the correct width for the rubber bushes to fit into the shock mount.

I got the turret mantle and recoil system back from the engineers yesterday. They had several attempts at removing the screws holding the recoil system in place. They couldn’t spark remove them and so they mig-welded bolts on the screws to see if they could wind them out. They kept breaking off so they arc welded them instead and that worked. As you can see, months of penetrating oil on these screws appears to have made no difference at all.

Has anyone pulled these recoil systems apart? Is the spring under load in the housing? Both recoil systems are a bit knocked about and as one is sold, I want to keep the best one for myself (sorry Lynn). It looks to me like stripping one down will be a challenge as well. There are NOS recoil systems still available so I will see how we go with this one.

I think I found out why my 37mm barrel was not straight! As per the photos, it looks like something has struck the barrel in two places, which was covered by the incorrect sleigh. I see also that the barrel has previously been cut near the breech and welded up. There is a bit of work to do there to tidy the barrel up before I put the correct sleigh that I have on there. I will also need to rebuild the mounts for the lever arm shaft and straighten the lugs that secure the recoil system coupler on the breech ring.

The intermediate and rear axles are progressing. Getting the diff housing bearing cones out was a problem but I understand a gas torch has now encouraged them to come out. I spoke to the engineering guys about the cracked differential housing and they say it won’t mig weld. We are going to look at whether it can be brazed but they tell me there is no guarantee that this will work.

Is there anyone out there with a worn M8/M20 differential who would be prepared to part with that part of the diff assembly? That would save me the trouble of trying to repair this piece which mightn’t be successful anyway. Thanks to Andrew, I might have some ready made gaskets coming to, so we are getting there.

Most of the hydraulic lines are cut and shaped now but I’ve still got to do the ½” tube.

That’s all for this week.