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

[Big D]

Hi all,

I’ve finally completed stripping the scout car JXD engine block. The valves tried my patience but I got them all out, albeit one taking a guide with it.

As I expected, it made a big difference being able to access the top of the guide where all the corrosion was. I got a bit creative and came up with the bright idea of using a mag drill and hole saw cutter to cut the top of the stuck valves off. That worked out good as it gave me access to the top of the guide and I was able to first scrape away and clean off the corrosion and then get some penetrating oil into the guide.

The block is now with the engine reconditioner for cleaning and crack testing. We’ll see then what the bores are like. He took a quick look at the valve seats and felt that two of them may need new seats inserted, but will confirm once he has had a closer look. He also thought that the main bearings and big end bearings might actually be fine, but will also confirm later. I see the big end bearings are already 0.060”.

The M8 manifold is blasted and painted now, although I’m not overly happy with the paint. It is just too flat and some surface rust is showing on the manifold already, so I’ll need to find something a bit heavier. I’ve pre-drilled the holes on the scout car block for the two extra studs required for attaching the M8 manifold. I’ll tap these once the block is confirmed as ‘good to go’.

I did a bit of panel beating on the sump but it still has a number of dents in it. Now that it has some paint on it, it doesn’t look too bad.

I’ve also continued some work on the recoil system. I will need to get some new strips of brass folded up to replace the damaged ones on the top of the cylinder. These strips are held into place by small brass pins. They almost look like an extrusion of some sort so I might try some of the surplus scrap dealers to see if it is something they might have on the shelf. I’ll also need to make up another brass bush for it to sit in the cradle as this only has one. I’ve re-tapped all the mounting holes on the cylinder and all are in good shape. I have also cleaned out the bore and it is nice and shiny. I am taking Barry’s advice and won’t be putting any oil in the tube.

I will need to make up a tool to get it all back together though. With the aid of a neighbour who is a retired mechanic, we spent a bit of time on it today trying a bit of muscle power, to see if we could compress the spring enough to get the coupler on the end. We weren’t able to do it though and I’d suggest it would be a three person job to be able to hold enough weight on the spring while screwing the coupler on the end.

I have in mind to use some steel plate at each end connected by half inch threaded rod. There are enough fixing points on the cylinder that I can attach it to and I’ll simply wind down the plate on one end and compress the spring. That’s the plan anyway…I’ll photograph what I make up next week.

That is all for this week.

[Big D]

More photos.

[Tony Smith]

Originally Posted by Big D

Hi all,

The M8 manifold is blasted and painted now, although I’m not overly happy with the paint. It is just too flat and some surface rust is showing on the manifold already, so I’ll need to find something a bit heavier.

Daryl, have a talk to these guys: http://www.hpcoatings.co.nz/ExhaustH...aspx#HiPerCoat

I've used their Australian counterparts's "Satin Black" on several Ford V8 exhaust manifolds, and the performance is superb. One pair of those manifolds have now racked up over 15 years with no discolouration or loss of coverage. Engine bay temps are lower, too. Cast Iron Grey would look the part, also.

The process is not a paint, it's a baked on ceramic coating that bonds to the iron. Not as cheap as paint, but your manifold will last for years.

[Big D]

Hi Tony

How's things with you? Thanks for that. That might be worth a go. Not happy with the paint and that looks like a good option.

[mark gillatt]

Rebuilt jxc block on milweb.

[Big D]

Hi Mark

Thanks for that. I checked it out and it seemed like quite a reasonable deal but I figure I have come this far with what I've got, that I will stick to it.

[Big D]

Hi all,

Most of my spare time this week has gone into completing the recoil system. This is the setup I used to put the recoil system back together. Others might have a better method but this worked well for me.

I used two pieces of 10mm plate at each end. On the coupler end, I cut a hole in the plate and welded an old bearing cup to the plate over the hole. The diameter of the cup was a good fit over that end of the cylinder. I welded another tubular piece of steel to the other plate to act as a locater for a ¾” socket to hold the nut on the end of the cylinder piston rod.

I used two 1 metre lengths of 18mm stainless steel threaded rod. The rod size seemed like a bit of overkill but it was all the local scrap metal supplier had on the shelf of a decent length, and the good bugger he is, he allowed me to take it home, do the job and then just return it.

I found that size of rod gave some reassurance when winding the tension up and compressing the spring and I wouldn’t recommend anything under ½” or 12mm. The 10mm plate was just starting to bend a little at the peak of the spring compression.

I got some brass folded up for the sides of the recoil system. I looked at buying brass channel but couldn’t find any the exact size. In the end I got a local sheetmetal fabricator to cut and fold some brass sheet. Unlike the original, the folding means there is a bit of a radius on the edges but hopefully with me using sheet that was slightly thinner than the original, this won’t be an issue. I used some 3mm diameter brass rod to secure the pieces to the cylinder. I will try the barrel sleigh on it soon.

An EBay search turned up a bronze bush of the same dimensions I needed for the mounting pin on the other side, so that is on the way to me. I am missing the little arm on the side of the recoil cylinder which I’m guessing is a valve of some sort, so I will find a suitable plug for that. I’ve noticed that the buffer pin on the head of the cylinder is bent, which is making it hard to screw this in, so I will need to straighten that.

I have the pedestal headlight mounting connectors completed and ready for hard wiring in the hull. Thanks to Willy for the electrical connectors and Paul for the black plastic housing.

That’s all for this week.

[Big D]

More photos.