Connecting Rod Question for the gurus or, Why it's Important to Label Your Parts Boxes

Wow, my first post under the new website format.

My son and I are getting ready to rebuild an A-code 289 from my first car, which was a 67 Cougar. I had begun the rebuild as part of a high school shop class project well over 35 years ago, but time got away from me, I guess. Anyway, among my boxes of parts, I find I have two boxes of pistons and connecting rods. I know that one box definitely contains the pistons/rods from my 289, but the other box must be a set I picked up somewhere along the way, possibly from a 302? Can’t remember. Anyway, all of the rods in one box bear C3AE casting numbers, as do all but one of the rods in the other box- the oddball rod in that box says C80E. Is it reasonable to assume that the box containing the C8XX rod cannot be from my 67 289? Is there any practical way to differentiate a 289 rod from a 302 rod by appearance?

They are different lengths. If it’s a 302 rod, it will be shorter than the 289 rod. 302 is 5.090, and 289 is 5.155. It’s not a lot, but side by side, you can see the difference. Ford did that so they could use the same compression height for pistons. They did use 289s in 1968!

What’s probably more important here is that the end caps need to match. Each cap has to stay with its own rod, or they have to be re-machined to fix the mismatch.

Thanks. All of the rods still have their respective caps in place. Looking at them, I can’t make out any difference. Maybe if I lay a straight edge across the joint between the cap and the rest of the rod, that would give me a center line through the big end and a common point of reference on each rod. The bottom surface of the wrist pin could be the other common point of reference and measuring between those two points I should be able to see if one rod is longer, right?

Yep! The distance between the pin hole and crank hole on the rods is where the length comes in. It will be noticeable if one of them’s a 302 rod. If it’s a different part number, so long as it’s the same dimensions and same size holes, it’s a non-issue!

After measuring all of the rods, both sets of pistons/rods are 289 except for that single C80E rod, which measures 5.090", so apparently, somewhere along the line someone must have screwed up a rebuild!