HI guys, I have a 406 (for sale for a good price if your interested) The previous post by tj61 was accurate, Thesse engines were not punched out 390, but rather built specifically to be 406, they have solid lift cams and kick out 385 hp stock!! The blocks have a higher nickel content than 428cj, have beefier main webbing area and improved oiling aided by the grooved crank. I have an entire running engine that I just pulled out of a 53 ford truck. It is still standard bore, I can sell the entire motor (minus the 3 duece setup as someone took it years ago) for 3750. I have pics and engine is located near Sacramento CA Email me at
jtboss302@lightningdrops.com if interested Thanks and cool site