Keeping this party going:
I've kept up with Eskimojoe and his two older D's for a while and when he added the '38 I was in a project hole. Since I also had a '38 this seemed like a good time to dust it off; it's always good to have someone to bounce stuff off. This tractor has always been hard to pull through when starting and the engine compression doesn't seem the same on each cylinder. The second thing could be due to valve adjustment, valve seating, piston/ring seal in the cylinder... et. al., but the fist thing always stymied me. I was told by the PO that he bought the tractor from someone using it in antique tractor pulls, so let's get into it and see what we have. Into the shop we go after a good pressure washing. Pulling the hood and fuel tank was just the start of the madness.
I fiddled with the carb a little and had it running again in the shop but the old problems persisted and a new one showed up (leaky carb float)... going to be down a few days waiting on parts, why stop now; better to just totally disassemble it. lol. Off with the radiator (6 fasteners).
Now we are getting somewhere, looking down the double barrel bore of the horizontal 2 cylinder design that Deere used from its early days until 1959 (Dubuque production tractors protected). That's 6.75" bore/side comin' at ya.
To this point I have used exactly these size wrenches: 9/16, 3/4, 7/8, and 1-1/4 for the head bolts. That's it, 4 tool sizes and I could have the pistons out. It's almost comical to compare it to rummaging through the toolbox for 16 wrenches and 2 specialty tools to change the headlight of a modern car - and you can practically, wait ACTUALLY, overhaul this tractor with 6 wrenches.
Mystery number one solved: why this tractor was so hard to pull though when starting it - these inserts were bolted to the face of the the flat-top pistons to raise the compression ratio. Little doubt the PO^2 did this for their antique tractor pulling - but I am going to do away with them and happily go back to the stock 3.9:1 compression ratio. I don't know what the resulting compression ratio was with these in there but I know it's enough to make your guts hurt if the tractor doesn't start with a few turns of the flywheel. The cylinder bores look good - which makes sense, these pistons are 0.090" over indicating a rebore sometime along the way.
That's where I stopped for now, one piston out.
Next I'll give the head/valves a really close eye to see if I can decipher the differential in compression between cylinders.
