[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.