Orange paint on connecting rods

[Keith B.]

These rods and pistons came out of a 73 512 327 block that replaced an L79. What does the orange paint signify on the rods

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[Don H.]

Re: Orange paint on connecting rods

I think those are called "pink rods". This picture shows a pink rod from an over the counter HP 283 short block. They also show the results of Fuel Injection hydro-lock!

[Keith B.]

Re: Orange paint on connecting rods

I have herd the term "pink" rods but I was assuming there would be dabs of pink paint, I have seen various colors of paint dabs on engine parts. but this rod looks to have been fully painted. I have no history of this block but it appears to have never been apart

[Duke W.]

Re: Orange paint on connecting rods

No, the "pink" rods are 2.1" bearing 350 rods. Raw forgings were pulled from production and Magnfluxed to check for flaws. Those that passed were machined and then shotpeened at the bolt and nut seats. They might have been heat treated to higher hardness, but I'm not sure.

The finished rods were then given a blotch of pink paint to ID Them. For sure they were used on the '70 LT-1 and L-46, but first usage may have been on the '69 L-46, and they continued to be used on subsequent L-82s.

The rods pictured in this thread appear to be second design 327 rods that went into production in the '66 model year. The little "hump" of material next to the bolt heads went a long way toward improving durability. The first design 327 rods did not have this additional material, and they are subject to fatigue failure at the bolt seat right at the 90 degree angle.

When I rebuilt my SWC's 340 HP engine in the mid seventies Magnaflux inspection revealed a crack clear across that "notch" on #7 rod. It was ready to let go any time. There was really nothing wrong with the engine. It ran strong as new and oil consumption of a quart every 1500 miles was normal for the loose fit forged pistons, but with 115,000 miles and knowing the rods were weak, I decided to pull the engine for inspection, blueprinting, head massaging, and a LT-1 cam. Hindsight proved it to be an excellent decision.

The only wear on any component outside factory new tolerance was the cylinder bores. Three were worn three thou and two were five. I attribute that wear to the Mickey Mouse foam air filter that wasn't much good at filtering out anything smaller than a hummingbird. The butt joint broke at about 50K miles the third time I washed it, and the dealer replacement was the AC A353C cellulose filter.

The orange paint in the photos was most likely done in the field, but I have no idea of its purpose.

Duke

[Duke W.]

Re: Orange paint on connecting rods

I think those are called "pink rods". This picture shows a pink rod from an over the counter HP 283 short block. They also show the results of Fuel Injection hydro-lock!

No, those appear to be second design 327 rods, so if the 283 was a GM crate engine it was likely built in 1966 or later since these rods were not released before that time frame. The little hump of metal next to the bolt seat is the distinguishing feather between the first and second design 327 rods, but if you compare a fifties vintage 283 rod to any 327 rods the former appear definitely spindly compared to either of the latter.

Duke