In addition to the small-block, RHS also offers heads for Chevy big-blocks ... Compared to the GM 906 castings, the Pro Torker Vortec heads offer an additional 27 cfm at .500 lift.

Q: Will Late 350 Chevy TBI Heads Work on a Carbureted ... 96-and-later L31 Vortec heads (casting Nos. 062 or 906) are superior to any earlier factory design, even '60s muscle car-era heads.

For this episode ofEngine Masters, presented by AMSOIL, we grabbed a set of as-cast Chevy Vortec heads, 906 castings in this example. The stock 170cc ports were left untouched, along with the 64cc ...

it created one of the best off-the-shelf iron cylinder heads ever made for the small-block Chevy. The 906 and 062 Vortec heads (referred to by the last 3 digits of their casting numbers ...