Trick flow 240 or 270 for 421 big block

On my 470 the 270 heads made more torque at 4000 rpm than the 240 heads. The difference was almost 50 ft-lbs. I know that sounds wrong but that is what happened.

Bigger heads usually kill off the lower end torque but if the smaller heads are too small for the engine then bigger heads work better. So that might be what is going on with my 470. The 240 head is fairly small and the port velocity is high. Perhaps it is too high and the larger port size of the 270 calms the airflow down enough that it actually works better from 4000 on up. Just a theory but we made a lot of back to back dyno pulls and the data was pretty clear. On my engine the 270 heads made more torque almost everywhere from 4000 to 7000 rpm. There was a weird little dip at 5200 rpm where the 270 torque curve dropped down but then it came back up. Not sure what that was, some sort of resonance or something.

This was with the Wilson standard port intake. The Indy intake didn't work all that well so take it for what it is.