Targa Miata
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October 28, 2013 - Curious.
The new valve springs look exactly like the old ones. I checked further, and the 12625033 is the standard spring on an LS3. So I was swapping these out for nothing.
The older 12586484 part number was an LS6 spring, and they were typically yellow. Interestingly, they also have the exact same spring rates as the current LS3 spring, with the only difference being a max lift of 0.570" instead of 0.550".
Just for fun, I peeked under the valve covers of a true LS367/525 engine and what did I see? Blue springs.
Busted! GM doesn't actually change the springs on these engines anymore. Even if they did, the rates aren't any different. The max lift isn't an issue, as the 0.525" max lift is the same as that found on the 480 hp "hot cam".
So I wasted some time and money, but I learned something. Isn't that how it always goes?
tags: engine