How To: Restoration of Ford M8 armoured car US Ordnance number 7373

[Big D]

Hi all,

Here are a few photos showing what I’ve been doing over the last couple of weeks.

I managed to get the recoil system apart. Thanks to Tankanic for his assistance. I had to make up another tool to remove the follower. Version 1 just wasn’t strong enough and I needed a big lever to get the follower undone. The photos show how it all sits in the recoil cylinder. I’ll have a closer look at everything when I am back in the workshop.

The new diff housing has arrived so I’ll be able to advance the axle assembly which I’m looking forward to.

I have a brake specialist folding up the 1/2" hydraulic line for the clutch master cylinder. The tubing was pricey so I figured I'd rather get it done right first time. Hopefully this will be done shortly.

I spent a bit of a time stripping the engine blocks to see what I’ve got and what can be reused. I got the flywheel off one of the blocks and the ring has a bit of damage. However, it looks like there is enough meat on there to turn the ring over on the flywheel. Out of interest I photographed the M8 flywheel alongside a White Scout car flywheel. As you can see, the scout car flywheel is quite a bit bigger.

On a side note, for what it’s worth for those doing Hercules JXD rebuilds, next week I will photograph the differences between the oil pump for the White Scout car and the M8 and post it here. I say that as I bought what I was told was a Scout car oil pump from a reseller for my Scout car engine rebuild and it turned out to be one from an M8. There are differences in the sumps as a result of the differences in the pumps.

That is all for this week...

[Big D]

More photos.

[Big D]

Hi all,

I am still waiting for the axles to be done which is getting quite frustrating now. If it is going to be too much longer, I’m inclined to go in and pick them up and do them myself now that my hand is right.

As well as doing a few odd jobs on the M8, most of my time over the last week has been spent stripping the three engine blocks. All three blocks are pretty tired with quite a bit of pitting on the tops of the block in and around the valve seats. The pistons and valves are all stuck so there is some work to break them all down. I’m not sure if any of the blocks will be up to the job but my aim is to get them all apart so that they can be assessed by someone with more knowledge than I have.

I have taken out the other two crankshafts that were still in the blocks. One crankshaft looks quite good and still had plenty of oil on the surfaces, but the other two will need some tidying up. I’ve had the pistons soaking with penetrant for some months in these blocks and now that I have all the crankshafts out, I’ve started the process of giving the pistons a good smack with a big hammer and a solid piece of wood shaped to fit in the bore. Out of the 18 pistons in the three blocks I’m working on, 1 piston has moved about 10mm so as I expected, this is going to be a long process.

As you can see, the tops of a number of the pistons are actually so badly pitted they can’t be saved so I am experimenting with another method of removal recommended to me. This involves drilling the top of the piston with the aim of breaking up the piston and or getting to the rings. I have plenty of valves and pistons and these are easily obtained, but good bores are not, so if I can get the pistons out and save the bores and rods it maybe worth a go. I’ve been told an air chisel is the way to do this but I don’t have that so I will progress with a drill and die grinder and see how that goes. I need to get penterant into the rings which will be what is sticking in the bore.

I’ve tidied up the bellhousing, engine mounts and timing cover along with a few other parts in preparation for a rebuild. It took me a couple of go’s to get the paint to my liking. I think it looks pretty close now.

For Oz and others rebuilding Hercules JXD engines, one of the photos shows the two seals for each end of the block. One seal has the unique rubber ring that goes around the seal in the block. I got these from Linda and Jerry at Hercules Parts, along with some other engine parts.

That's it for this week.

[Big D]

More photos.

[Big D]

Hi all,

A little bit more progress on the engine side of things which might interest the guys looking at doing Hercules JXD’s.

I’ve cleaned up and prepared a few more parts for the engine rebuild. It looks like there are a couple of types of thermostat housing as I have two types here. I haven’t worked out which one I’ll use yet.

I’ve been working on the fan pulley assemblies. One of these has a broken pulley and is seized. The other one was completely rusted up and I had to soak it in molasses some years ago when I first got the project. Neither is going to come apart easily but I’m hoping I’ll get one good unit out of the two. I have another good fan pulley on the way to make up the two required.

I checked out all three cylinder heads I have here and I see there are differences in them. I picked out the one that looks the best and cleaned it up with a wire wheel. The thermostat housing was a bit of a dog to get off as the internal nut and the stud in the cylinder had corroded and become one. I used a die grinder in the end to knock off the side of the nut and that has saved the stud. I think this head should be okay and I can’t see any obvious defects with it. There is a bit of pitting on the surface so it will need to be planed. It is ready now for a dip and closer inspection by the engine reconditioner.

I’ve attached some pictures of the other cylinder heads I have. The one pictured with the head that I cleaned up is off a scout car engine but I see it has a fine crack through to where the thermostat housing bolts on. This head appears to be the same as the other head I have which has some damage to one of the head bolt holes. Are there differences between the M8 and Scout car heads? Is there any difference in the compression ratio? Is the one I have cleaned up for an M8 and the others are for Scout Cars? I will have to investigate further.

I have made some progress in removing the pistons with three out of the bores so far. I certainly recommend the option of cutting out the top of the piston and attacking the rings from in behind, providing the piston is expendable and the pistons are at TDC. I can see now that five of the six pistons are pitted on the top so they’ll need replacing anyway. I see also that these pistons are .060” so the engine has been rebuilt at least once before. I wonder if the fact that it is at maximum oversize now has contributed to one of the cylinder walls collapsing? Anyway, the three bores where I have removed pistons look good. We’ll see how bad the others are. I can only see one hole in one of the bores so hopefully there is enough meat there for the cylinder sleeves.

That’s all for this week.

[Big D]

More photos.

[Big D]

Hi all,

Here are a few photos now that I have the pistons out of the block. I’m glad that the pistons were not reuseable as it was a real battle getting them out and as expected, the pistons are now a sad sight! Four out of the 6 bores are not too bad. As you can see cylinder 5 has quite a hole in the cylinder wall. You can probably make out in the photos that the cylinder wall is actually quite thin there and as I said in my last post, I wonder if .060 thousand oversize is pushing it on these blocks. Cylinder 6 has a bit of damage from where the rings and the bore had become one. Structurally though, this cylinder and all cylinders bar cylinder 5 are sound.

I guess the reconditioner will determine whether the condition of that cylinder makes it a viable option for sleeving. I can’t see any reason why not providing the sleeve seals around that hole in the wall, but then I am no expert. Hopefully I haven’t wasted about 2 days work in getting it apart so far!

I am almost inclined to get the reconditioner to assess the block first before I try to get the valves out as I can see these are going to be a battle as well. All are stuck in the guides and I suspect there will be plenty of pitting around the valve seats once I get the valves out. I doubt whether any of these valves will be reuseable and I will be replacing the guides and springs anyway, providing the block can be rebuilt. Does anyone have any bright ideas on the most time effective way of getting the valves out?

The engine sump holds oil but is a bit of an eyesore and I am debating whether to repair it or not. It has several internal baffles so getting access to the dents is impossible without cutting the bottom off the sump, panel-beating it and then welding the bottom on again. I am a little hesitant to go that route though, as cutting through the sump without seeing what is behind the sump wall might be risky. Alternatively I guess I could drop it off to a panelbeater and get them to try pull out the main dents.

I have seen worse sumps than this though and I’m confident that the majority of the oil would drain during engine change. However, it does look ugly. Thoughts anyone? Has anyone done such a repair?

That's it for today.