Nothing wrong with good flow at low RPMs either.
Very true - but heads designed to flow well at high revs will never have as high velocity at low revs as small port heads, losing low speed torque to the small heads.
The 1970 + head was designed with large, good flowing ports & large valves, intending to win races at high RPMs.
The 291c type ports are competitive with the early hemi when fully ported, polished, & big valved.
Large, high flowing ports necessarily are not as good down low as small ports. It is pretty hard to make large ports smaller. You should get some low speed velocity back by using the small valve 304 heads, although I have never seen the flow number for the little heads.
Goose, you are missing the point, moving the peak down the power band DETRACTS from the design of the heads. The heads are designed to flow well, which means that they will not have as high velocity at lower revs as smaller ports would have, meaning smaller port heads (290/304) will have MORE torque down low than the larger 291c style heads.
And since you brought it up, valve diameter to displacment ratio for the AMC ain't all that good (SBC is better), so you would not want to go smaller than the standard 2.025,1.65 valves for the 360-401.
Any engine that is run so slow that it never exceeds the flow capacity of a certain sized valve does not need a larger valve and will lose low end performance with larger valves. I always go for 2.08/1.74 & will go bigger when I can afford it!!!
My point is, that if I build a 401 to ENHANCE the performance of the heads, I can get over 500 ft.lbs. of tq. (400 ft.lbs. just above idle) & over 550 HP BOTH (65007000 redline), where the low RPM build will max out at around 300 HP, well over 200 HP LOST to the 25006500 powerband build.
Don't blame me for the laws of physics!!! Small ports will make more tq down low, big ports at higher revs!!!
