Join Date: Feb 2002
Location: N.W. Washington
Re: Drilling Heads for 400
This is a long debated subject. That said, from my experience, the research I did prior to building my first 400, and everyone I know running them (quite a few guys), they are not needed unless you plan on idling for hours in the heat, and I mean hours.
The only reason GM did it was because they need to design a motor that can sit at idle and below 1700 rpm the majority of it's life in Arizona type heat. Not one manufacturer I know of of aftermarket siamesed blocks drill holes in them if thats any indication.
As I always have said in previous discussions, by all means drill them if it makes you feel better, but as Bill points out, it's not a slam dunk piece of cake to do yourself, so you will end up paying to have it done likely. I will tell you this, I have seen way more guys sorry they tried to drill the holes and make a mistake (several) than guys that wish they had drilled them (none).
1968 rs with an old school 354" SB2.2 pump gas motor.
Repetition does not transform a lie into a truth.
Franklin D. Roosevelt