I'm going through and inspecting my disassembled 350 parts and noticed that on about half of the rods, the small ends have blue heat discoloration. It's pretty heavy on one of them. I don't see any scoring on the pins, and the pistons still pivot smoothly on all of them.

First question is this: What would cause the discoloration to isolate in that one area like that? The pin doesn't swivel in the rod, and it doesn't appear to have broken free and spun at all on any of them.

Second question: I don't see any visible cracking on any of the rods, and I plan on having them magnafluxed to check for cracking. If they are crack free, are they safe to use again? I'm not planning on anything to crazy, just 400-450 HP/TQ all under 6000 rpm.

Thanks for your help guys, I'm still pretty new to the inside of the motors

 

changing pistons, it's no big deal

 

Usually when a shop or who ever installs piston to the rods (non floating) you need to heat the rods up with a torch.

I know mine had heat discoloration when I had my pistons mated to the rods.

Could this be what that is?, cause outside of that ???

Ron

 

That would definately make sense as to why the heat marks are isolated in that one area on all of them

Thanks guys

 

Just about all the re-used stock rods that go in my engines have some "blueing" on the small ends from taking the pins in/out. Haven't blown one up yet.

Since most aftermarket pistons these days are already grooved to take the retainers required to use "full-floating" pins I've recently taken to having ALL my rods honed out for full-floating wrist pins (with appropriate oil hole drilled in the top). That way you only have to have the rods heated ONCE to remove the stock wrist pins and then you can take the pistons on and off yourself iin your workshop as many times as you want from that day forward, without having to heat up the rods again or take them to the machine shop to get them pressed on/off. More a convenience thing for me, but might be something to think about.

 

I'll definately ask them how much they'd charge when I take it in. Think that would free up a couple horsies too? A tiny bit less friction at 6000 rpm... Maybe?

 

Don't expect to feel the difference in the seat of your pants. Maybe a tiny fraction of a tenth at the strip.