I forgot to mention the bolt bosses being removed and lumps installed. I can see where these engines have breathing problems. It was in their design, with a "potato" stuck in the middle of their wind pipes...lol... I have read it can be improved, not much, but improved over stock. In any engine I build or do improvements to; torque is my main goal along with maximum vacuum at cruise rpms. I can't care less about horsepower.
I wonder if they had improved the head design for better flow, if these engines would have still fallen from popularity. I mean, we love them because we want to keep our trucks stock for the most part, but if we can get a tad more power, why not, right? Nowadays everybody is worried about laying rubber on the road, racing to the next stop light and stop sign and making as much noise as possible.
