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

[Big D]

More photos.

[Big D]

Hi all,

I’ve continued with the assembly of the engine as well as doing a few jobs on the hull. A few of the last parts I was waiting for also arrived (thanks Taylor and Brian).

I had to rebuild the fuel filter, so that is all done now. I’ve also plumbed the clutch slave cylinder on the side of the gearbox. This is using 5/16 tube instead of the standard ½” tube so I’ve had to get a flexible hose made up for it. I am using ‘olive’ type connections on the lines at the gearbox end, rather than flares.

My retired auto-mechanic friend and I attacked the bleeding of the hydraulic throttle. He was fairly adamant that his good old vacuum pump would do the job but we found that it just couldn’t generate enough suction to draw the fluid up over the ‘hump’ in the line at the front of the hull. After that he dug out an old pressure builder he had made several years ago and we adapted that for the M8. I couldn’t find a spare reservoir cap with the necessary 1 ¼” -18 diameter to modify for the pressure bleeder. However, I did find a cap that was 1 ¼”-16 diameter and using a bit of plumbing tape got enough of a seal in the reservoir to get sufficient pressure into the system. I have to say that this worked a treat. Perhaps it was a little too good as it was a great way to find multiple leaks in the lines! A little bit of tightening here and there on the flared connections and some water to wash the hydraulic fluid away and we were almost there. We bled at the junction point that I made up and then we disconnected the pressure bleeder then and used the vacuum pump to finish it off at the bleed point on the slave cylinder. Ten minutes later and I now have a working hydraulic throttle. It feels very smooth.

Up until a day or so ago, I hadn’t found the correct screw in connectors for the ignition leads sold separately. I thought to get around that I would use ¼” UNF cut off screws and use standard distributor ignition connectors to fit over the threaded shafts in the distributor cap. In the meantime, I got a ‘lead’ on where I could find the correct connectors and they are now on the way (thanks Brian).

I didn’t realise that there were the remnants of the old temperature sensor still in the head so I had to remove that with a ½ NPT tap. I’ve fitted a new sensor now. Hopefully this will match the temperature gauge I have.

The generator is mounted on the generator mounting bracket using two large 5/8” bolts. These bolts have a shoulder on them with the diameter of the bolt shafts a little bigger for the corresponding holes in the mounting bracket. Unfortunately I only had one of these bolts and it is not the sort of thing you can get off the shelf so I had to get a ¾” bolt turned down instead. It makes for an expensive bolt!

I have run out of time to find a replacement pulley for the generator. The one I had was broken in three pieces and had already been repaired once. I have had it brazed up by the guys in the engineering shop so hopefully it will do the job until I find the elusive replacement. Does anyone know about balancing these? If you look carefully at the photos you will see that the splined hole for the generator shaft wasn’t even centred when this was manufactured so I’m not sure I need to worry about the balance….

Is anyone still supplying rebuild kits suitable for modern gas for these fuel pumps? They seem to be harder and harder to get…

That’s all for this week.

[Big D]

More photos.

[David Dunlop]

Darryl.

Do you have a bare splined shaft available the gen pulley will fit on?

If so, you could centre the pulley on the shaft and place the assembly between two hard level surfaces (steel or glass is best) and see if the assembly stays where you placed it or rolls to a different point and stops. If the latter, the assembly is out of balance and has stopped where the most weight is at the bottom.

Seems odd that somebody milled out some metal between the fins on that pulley on the ‘short side’ of the shaft hole. I would have thought that would have made the ‘long side’ even heavier.

David

[lynx42]

Hi Darryl, any reason that you have put the generator pully on back to front? The fins should be up against the generator face not out there where you can get caught on them. The fins are to push cooling air through the genny.

Doing a great job. I'll have to pressure feed my Lynx hydraulics to find the leaks.

Cheers Rick.

[Big D]

Hi Rick

Good spotting. I had been playing around with the pulley and its alignment at the time. I have put it on the correct way since then and it seems to spin evenly enough.

Yes, I was impressed with the pressure bleeder option and ordered one of these from the US. It seemed to have pretty favourable reviews from what I had seen and really the only drawback with it was the lack of a release switch on the output. The hydrovac should be done this week so I will hopefully have this bleeder by then and will use it to bleed the brakes.

[Big D]

Hi David

Not a spare one, I’m afraid. I did play with the pulley on the generator spline both ways and I actually think it will spin okay. I will keep an eye on it when we hopefully fire up the engine next week.

[lynx42]

Originally Posted by Big D

Hi Rick

........

Yes, I was impressed with the pressure bleeder option and ordered one of these from the US. It seemed to have pretty favourable reviews from what I had seen and really the only drawback with it was the lack of a release switch on the output. ......

I reckon I could make one of them up with a garden weed sprayer. Let you know.
Cheers Rick