Connecting Rod Mystery

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peck_az

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Well, I got into my '72 318 and discovered a bit of a mystery. The connecting rod casting numbers are 3418635 which, to my best knowlege, are press fit rods from 74-up 318s and all 360s. What is even more of a mystery is that these rods have floating pins. There is a bushing in the small end.

Also, there is no oiling hole on the small end of the rod. Do small block floating pin rods normally have an oiling hole?

I do not believe that this motor has been apart. If it has they covered evidence of it very well.

Does anyone have any comments on this?

Thanks
 
If memory serves me right, most all floating pins have a small oil hole (scavenger oil) to lube the bushing , whereas the press fit pins don't rotate in the small end of the rod so its not necessary to lube the small end. The pin gets scavenger oil at the piston where it does rotate
 
I've looked through alot of these rods- The casting number is the same for a boring old 360/318 as the hi-po floating 340's, the only difference is the 340's are bushed. I've never seen a 318 with factory bushed rods but with mopar you never know. And the factory never drilled the holes in the bushing, I guess it took too much time or something. I drilled my own for extra insurrance in my last motor, but I did another 318 without drilling the holes and there hasn't been any problems. Also the bushings never look like they were starved for oil so its up to you. I know every other manufacturer drilled holes for oil, but mopar must not have thought it necessary. Another thing if you have a set of stock rods and want them bushed- it is possible to hone out the small end and install the bushings- if your worried about it.
 
i have a set of 340 rods, casting number 3418645, they are bushed with floating wrist pins. they do not have any oiling holes drilled into the pin end. i did buy a set of direct connection rods new 15 years ago. i do not recall the casting number or part number. they came with hi strength rod bolts, polished beams, bushed for floating pins, & were drilled on both sides of the pin for oiling. they did have a logo cast into them, DCP, which i assumed was for Direct Connection Parts. however i have seen this same logo on stock 360 rods with pressed pins. the one thing about the world of mopar, never say never, any thing is possible. when you have the smallest budget of the big three, if you can use one casting number in several applications with slight machining, then Chrysler would have not been above doing it!
 
I have two sets of rods that have that same number that are bushed. One set came out of my 1973 340 and the other I purchased at a swap meet. In the early 70's some 318's did come with floating pins. I don't know if these were to be truck motors or just built in a different plant that was using floating pin rods. But I have seem them before.
 
The set of rods that came out of my 1973 340 has 4 that are copper plated, anybody ever seem this before?
 
Yeah..I have had a couple of '71 engines, 318s, that had them. I was told it's a trick to make usable connecting rods that were over machined..they coat them with copper to get make the ID smaller, then refinish them, instead of tossing them in the trash. I never had a problem using them, but you're the only other person I have heard that has them...lol.
 
You know that is one of the rumors that I have heard about them but I can't see why they couldn't have just ground a little off the cap & rod and re-sized them thats what machine shops do. The second story I heard was they did this to add weight to them. I am curious to know what was the real reason or to confirm what you have said.
 
It was to add weight and material, ford does it alot, but not as common as mopars. Working in a machine shop I get to see all kinds of different versions, In our rod room theres at least 1000- 2000 sets of rods, anything you could think of. And the early 70's 318's that were floating were the "light" duty rods- not as strong, skinny beam.
 
when we tore down the 71, the rods were the skinny ones. The guy at the machine shop had a set of 340 rods laying around, so he gave them to me free of charge, and re-sized them. Nice thing about a 318 and a 340... same stroke. The 340 rods are alot beefier!

Wheres the beef? in a 340 rod!

Triggerjay
 
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