Those are the pros and cons. So how does it wash out? In practical terms, the Magnum heads, as delivered, certainly aren't race heads, but they make for a nice performance street piece. Out of the box, the potential is there to make 400-plus-horsepower with a well-thought-out street 360 combination. While those power levels were possible with the early 340 heads, the chamber design of the new Magnum-when coupled with the appropriate quench clearance-provides a noticeable torque advantage and greater detonation tolerance as compared to the older design.
So what does it take to bolt a set of new Magnums on an old block? Though the heads have been around for years, we've heard urban legends about required changes, when really, all that's required is to select the correct compatible components and bolt them on. We consider it a simple conversion. Follow along as we add a set of Magnums to a hot 360 short-block and see if you agree.