Curious about AAR/TA Heads

Opening the pinch doesn't make much difference unless you are making some real horsepower. We actually did a test like that on a pump gas 424ci/360 with the Indy/RHS LAX head. Calculations said the pushrod pinch would choke the engine @ 6,300 rpm............and it did make 620 HP there. Those heads have big pushrod holes so we plugged them and drilled smaller holes and opened the pinch. The engine jumped to 629 HP and held more power into the rpms. I've often wondered what would have happened if I had drilled the hole offset and used offset rockers to open the pinch even more.

Generally we've only opened the pinch to make it a bit easier to get to the more important areas in the port.