[Big D]

Hi all,

Progress on the M8 the past couple of weeks is still a little slow with most of my time going into working on the Scout Car, so I’ve just been tinkering away on the M8 when I can.

We got the M8 crankshaft assembled into the block last week. The journals on this crank were at 0.060” so near its limits for wear but it looked to be in nice shape. All appeared good until we measured the end-float which was over 0.011”.

After some searching for the problem we identified the problem as being the crankshaft itself. The gap between the rear main bearing shell thrust washer face and the crankshaft journal was too great. It looks like that journal where it meets the thrust washer has been ground at some point, possibly in the process of its last refurbishment?

Why that would be is a mystery but we were wondering why the rear main bearing shell had punch marks around the circumference of the thrust washer face of the shell and this would explain why. Whoever did the last work on it was trying to take up the excessive clearance by putting the punch marks in the shell and dimpling the thrust washer surface.

After some discussion with the engine reconditioners I decided to go with the option of resurfacing the thrust washer face of the bearing shells. This has the effect of building up the surface and taking up the excessive clearance. Apart from the end-float the crankshaft is in very good condition and I felt that it was a shame not to use it especially when we had gone so far with it. Now that the crankshaft is back in the block with the resurfaced shell, the end float measures at an acceptable 0.003-0.004”.

I do have a spare crankshaft which is at standard size along with some 0.020” shells but I will save that combination for a future rebuild on either the scout car or the M8.

I have a number of other parts on the way including the water pump parts I needed (thanks Brian). I am in the process now of gathering up all the loose parts and taking them to the workshop where I will assemble all the bits and pieces onto the engine prior to lifting it into the hull. The gearbox synchro rings are due here anytime so I’ll be able to reassemble the gearbox and get that fitted to the engine block before the assembly goes into the hull.

I had the generator that I rebuilt tested at the local auto electricians and it tested fine. I can’t say the same for the voltage regulator. I bought that believing it would work but it is a no-go. Fortunately I have another which looks like it has never been used so I will test that one out. Despite it appearing to be NOS, I had to solder a wire back in place. It had broken away as one of the coil mounts was loose. I still need to find another pulley wheel for the generator, or else repair the one I have.

I am making up an ignition lead harness. I had the tubing but it came without cabling in it. Complete NOS ignition lead sets are available but I figured I might as well use what I had and the leads don’t take long to make up.

I have the later thermostat housing and pipe outlet. I tested the NOS thermostat I had in the thermostat housing and I see the fit isn’t right. This thermostat is a French one – part number G136 73 47630. The length of the thermostat means that it seems to be pushed hard against the inner surface of the housing so I don’t see how it could work. The 3” diameter at its widest point also makes it a little big for the water pipe outlet to fit against the thermostat housing so that the two pieces close.

I am aware that there are different types of thermostats and housings but does anyone have any photos of the variations of these so I can confirm things?

That’s it for this week. Merry Xmas.