The Crankshaft/Oil pump Assembly

I apologize for not showing these parts in greater detail. While the crankshaft and oil pump can indeed be taken apart, the fits are a combination of close tolerance, doweled, and some aggressive press fits thrown in for fun, and I simply couldn't justify disassembly!


The crankshaft, oil pumps, and main rear bearing temporarily assembled. A radial engine uses a single-throw crankshaft. Notice the brass counterweight cheeks. My plan is to calculate the balance necessary, then pocket-mill the counterweights and insert either lead bird shot (vibration dampening) or a large carbide insert.

A closer view of the business end of the crankshaft. Note the oil groove on the master rod journal. While not hollow (common in full-sized engines), an oil pathway has been drilled. The oil path starts at the rear main bearing (inside the bronze oil pump housing) and flows to the master rod journal where it is delivered to the groove. It then flows forward to the front main bearing, whose groove is visible in the top photo. This oil also splashes the cam ring and tappets in the front section.

The master rod/slave rod assembly. The plans called for aluminum connecting rods. I chose steel for strength, at the expense of weight and possible imbalancing, which I hope to correct. Note the spacing of the link pin holes in the master rod... they are not 40 degrees apart, as one would expect for nine cylinders. Rather, they have been mathematically corrected so each rod delivers its piston to TDC at each 40 degrees of crankshaft rotation. This produces less side loads on the connecting rods, and a smoother running engine.

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