That's from installing the wrist pins.
The small end of the rod is heated so the hole expands then the pin is inserted..


ks

 

So, that doesn't account for the port side rods lacking discolouration.
Also, forgot to mention. The engine was run w/o oil for a short duration ten seconds or so.
Sorry, didn't know it was in that state.

 

If the wrist pins are pressed fit onto the rods then that is normal discoloration from heating the rod up to expand the rod and slide the wrist pin in.

ks

 

is that thing cracked?

 

is that thing cracked?

Great observation!

No. It's a scuff mark from some tooling I guess.

 

I've never seen a rod break in the pin area from that heat. I have seen many break either in the beam or at the big end where the rod and beam kind of come together. Plenty of rod bolts as well. Nonetheless I still don't trust press fit rods at elevated RPM (6500+). For stock applications they're fine.

 

They are cheap, they are not "fine" ...

 

Here are my Valley Head Service (of Carrol Shelby fame) worked over 289 rods with pressed pins. You can see the slight discoloration from where they were heated to install the pin. Reused with new pins installed on the second version of the engine. Still only slight discoloration from where they were heated. Whoever installed the pins on your rods, made sure they had ALL the heat to install the pin!

These pressed pin rods survived many miles and I’m not sure how many passes in the eighth and quarter mile over several years shifting as high as 7500 RPM. But it was only a 289 crank with 2.87 inches of stroke. So piston speed was low.

Fun fact. The pistons attached to those rods were designed by Mark O’Neal and purchased from him through Woody back when I used to be a moderator at Woodys forum and Ford Strokers was in its infancy. The good old days!

 

My latest 289 stroker build ( 3” 302 crank over the previous 2.87” 289 crank) does use floating wrist pin rods. More rpm and significantly more power. Full floating is always better even if not needed as was the case in my previous two 289’s.