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Odd and Even connecting rod offset information


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I recently started building a back up 6 cylinder flathead engine for my truck. All I got was the block and crank. I had a set of connecting rods and pistons from a prior engine build but may likely get a new set of pistons as they appear to be standard bore. I was trying to remember about how the offset worked on the connecting rods and I will share what I found out about the offset of the rods. Even though I have found some information on this site it seems to be pretty scattered about and I found myself wanting for clarification. This is my take from what I have seen with my engine and connecting rods.


Factory rods for the 23 inch 218 and 230 engines are numbered 1-6 at the rod end caps denoting which cylinder they go to. The numbers are not always clearly stamped and in some cases nonexistent. I have read of several instances where engines may have a number 3 rod on a number 1 journal. I assume this is ok if a rod needed to be replaced as the offset would be correct. On rods 1-2 the thinner sides of the wrist pin boss goes together. Same on 3-4 and 5-6. The Connecting rod bolts are offset as well. Facing the camshaft side of the engine with the #1 connecting rod to the right, the #1 rod bolts are offset to the right and the #2 are offset to the left, same with 3-4, and 5-6. When rods are not clearly stamped, scuffing with a scotchbrite pad on the sides of the rod and cap will possibly reveal a number on the rod and/or the cap. 

This is only based on my experience with my engines. Other may have had different experiences and your contributions to this thread are welcome even of your experiences contradict mine. 

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