The 406 was Ford?s answer to the #evy 409. It has a thicker cylinder wall and a 4.13 bore. It is similar to the 390HP block with thicker main bearing webs and horizontal support ribs and has the same crank dimensions as the 390, but was NOT just punched out, it was cast with the intended displacement of 406. The early blocks did not have the cross bolt mains until mid 1962. This was in response to racers having problems with crankshaft ?walk? at sustained rpm?s. The 406 eventually evolved into the 427. None of the 406?s were side oilers, although many have the cross bolt mains. They were considered a very well made engine and if properly assembled should last as long as any FE. I think they were only offered from 1962 to 1963, but I am uncertain. The 406 is considered ?rare? as FE?s go but occasionally one turns up. Make sure you don?t confuse the FE 406 with the Mercury 410 or some sort of stroked small block! Check on the FE forum archives for better and more detailed info. That forum is outstanding and has the real experts on it. It is not interchangeable with the Windsor, Y-blocks, Clevelands, or the 385 series (the 429, 460 engines).
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Tom Johnson
Tj61@juno.com