Is 426ci 360 a small block?

Lelo Dart said

Try those E3 plugs?

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After a series of pulls with the E3 plugs there was no gain in peak horsepower. There was an average gain of 2.5 lb-ft of torque and 2 hp in the 3,000-6,000 rpm range. I have not been checking the averages above 6,000 rpm.