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Rod bearing locating tangs

Practical Engine Building

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Hi there. Should the big end bearing locating tang (the bearing that's on the rod NOT the cap) be facing the front of the engine? I am speaking with reference to a NON-V configuration engine where theres only 1 rod per journal.

Connecting rods are symetrical, so that isn't an issue. The bearing loads are not symetrical, though, and there is a greater loading under the power stroke, and this is biased in the anti-clockwise direction of the bearing, looking from the front. The way I consider it, and opinions WILL vary, is that the tangs may cause a slightly compromised support area whereas the full bearing support will potentially offer a little more support. So, looking from the front of the engine, I place the tangs to the right side of the crankshaft. I don't know if that's the 'front' or 'rear' of your engine, as the engine orientation will affect that.

I guess if im looking from the front of the engine then it would be the same for every conrod regardless of whether its the front or rear of the engine, yes?

alright, understood. I was under the opinion that the locating tang of the rob bearing (fixed to the rod) should be toward the front pulleys

Why I said "opinions WILL vary" ;-)

Oops, I see I didn't phrase the earlier comment clearly - when I said 'front' of the engine, I meant looking from the pulley end of the crankshaft with the flywheel further away. Should make more sense now?

Some engines will have 'left' tangs and some 'right' tangs - I don't expect it to make much difference, TBH, when all's said and done, as the primary force is directly along the line of the con-rod and side loading is effectively limited to inertial loadings and the shells usually have slightly more clearance to the side to allow for big end distortion under high tensile loadings.

With paired rods on a common journal, as I think you're aware, there will usually be a larger relief for radii clearance on one side of the 'rod, this takes priority.

Ah yes. Makes sense now. Thanks gordon

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