So I'd mentioned back in post #17 that I'd finished the bottom-end reassembly, but never got around to a detailed post.
No-numbers replacement crankcase.
This crankcase was in good shape overall however I did find a single crack near the final drive area. Looks to me as if the person disassembling this engine missed a fastener and tried to lift the cases apart with one bolt still in place.
This is a non-stressed part of the case, so rather than having it welded I chose to fix this with JB weld, like so:
Cleaned everything thoroughly with acetone. Blew some pressurized air through the crack to dry things out. Marked the damaged area, masked things off. Warmed up the crankcase with a light bulb.
Inserted some long bolts into the adjacent bolt holes and then applied pressure with a set of welding pliers to spread the crack out ever-so-slightly.
Mixed up some slow-curing JB Weld.
Pushed this through the crack from the inside using my finger until the JB Weld oozed out the other side of the crack.
Cleaned the excess from the inside and outside of the case, then released pressure on the bolts. Good squeeze-out observed on both sides, indicating plenty of JB Weld inside the crack.
Placed some wax paper across the mating surface to avoid things sticking together which shouldn't. Bolted the case halves back together. Pressure from the fasteners caused the crack to want to close up on it's own, this squeezed some of the JB weld back out of the crack.
Left the crankcase to dry overnight.
Disassembled the case, so far so good.
As you probably noticed above, it was not possible to get the JB Weld worked in the the full length of the crack because it was more of a hairline fracture away from the mating surface. What I had accomplished at this point was to bring the part back into shape/alignment. Now I'd seal the rest of the crack to prevent weeping.
Masked off the area again and chucked a carbide cutter into the Dremel.
V-grooved the full length of the crack on both the inside and the outside.
Mixed up some Fasweld repair putty. This is a reinforced epoxy putty that is extremely simple to use, fast drying, and has some pretty amazing strength. I actually keep a stick of this stuff in my car at all times in case of emergency, I literally don't leave home without it.
To use this stuff, cut off a hunk and then knead the stuff together to mix the two components. This stuff has the consistency of somewhat dry modelling clay, so I wouldn't have been able to use it above to seal the inside of the crack, but it'll work well for what comes next.
Pressed and formed the Fasweld putty into the V-grooves. Molded the putty into a pleasing shape that blends with the existing contours. Tried not to lay it on too thick. There's plenty of clearance on the inside of the case (checked with clay and the tranny shafts in place, plenty of room). Once the putty dried, I sanded it down a bit and then used an extra-fine honing stone to make sure the mating surface was completely flush and smooth. I touched this area up with some paint and the repair is practically invisible.
