Continued work on the cylinder head by adding the features shown below. Oil is pumped through the camshaft to the cam lobes. This oil drips down through the cam boxes and collects on the heads where the valve cages are. There needs to be a trough machined to collect this oil, and then drain holes to allow it to drain back to the crankcase.
Also added the threaded mounting holes for the cam box and the manifolds, intake and exhaust. These holes may need to be moved when those other assemblies are worked.
I also added raised bosses for the coolant tubing flange. As shown above I do not see this on the original engine but it is nice to have the additional material for the flange mounting screw to bite into. The head coolant passage is just below these holes.
Bottom View of the head with the deeper combustion chamber. There will be many additional holes on the bottom of the head, but these will be defined as part of the block, then their positions transferred to the head. If needed they may be relocated.
Due to my work with the new combustion chamber and recalculating the compression ratio, I have revisited the Crankshaft design. By shifting some of the dimensions around I was able to increase the stroke from .75″ to .875″. This additional stroke with the larger combustion chamber and a flat top piston give me a reasonable 6.3:1 compression ratio. There will be repercussions to the inside of the crankcase as there are now interferences, but they can be easily addressed.
Latest Crankshaft design – This can be compared to the initial crankshaft drawing to be found in an earlier post. I was able to increase the stroke by going to a smaller connecting rod journal, this also reduced the thickness of the crank stock needed from .625″ to .5″. I also added the crank pin lightning holes and oil galleries. The ends of the crank pin lighting holes will be plugged to allow oil to flow from the main crank bearing out to the connecting rod journals.
Block Design
OK, now I am turning my attention to the block.
Here is the block with a single cylinder sleeve installed. I need to add some holes to:
- mount the block to the crankcase
- mount the head to the block
- Water passages from the head
- Oil passages from the head to the crankcase
- mount the side plates
I think the best approach is to lay the holes in by eye and then move them around to allow for the most amount of material around them and to insure they do not run into each other. It will be very important to maximize the amount of surface area around all of the holes at the head to block interface. There is a lot of combustion chamber pressure attempting to blow out our head gasket.
Above and below are pictures of my Wallaby block showing the holes that need to be added.
The screws that secure the block to the head will be mounted from the bottom, through clearance holes in the block and threading into holes in the head. I am wrestling with what way the screws should go to secure the block to the crankcase. The outside holes and the center holes are easier to mount from the top, down from the block, because there are webs in the crankcase supporting the crankshaft bearings in the way. The holes between cylinders 1 and 2, then again between 3 and 4, are behind the oil return tube and would be easier to install from the bottom, from the crankcase side. These are identified below as the screws that I may not be able to access behind the oil drain tube.
If I relocate the oil return tube, I can insure that I get a full 60 degree swing on the allen wrench.
I had to redo the holes securing the block cover, these will not match the original, but this combination minimizes interference between holes.
This is the current state of the block, a dizzying array of holes