Join Date: Feb 2002
Location: N.W. Washington
really, if it will make you feel better, go ahead and drill them.
but, with that said, no, you don't need them. that is unless you plan on spending 90% of your time at under 1500rpms, which is about the only time steam would build up at the siamesed area. yes, GM did it and they know what thier doing, but they were also building motors for delivery trucks, taxicabs and police cars, not a performance (or even semi performance) motor in somebodys weekend cruiser. just look at any of the aftermarket siamesed blocks, none are drilled for steam holes, at least that i know of. and they too know what they are doing.
and btw, this is info i acquired long before i did it myself, from several respected machinists. and i and every one of my friends that run 406's do so w/o steam holes, fwiw. all it really ends up being is a place to crack, something factory 400 heads are notorious for. but, you could absolutely do it, and probably be ok, so really, if it makes you feel better go ahead, but imo, its unnecessary.
enjoy your new 406! [img]graemlins/beers.gif[/img]
1968 rs with an old school 354" SB2.2 pump gas motor.
Repetition does not transform a lie into a truth.
Franklin D. Roosevelt