in my 700 hp 500" motors, the 337 was worth about 25 hp. it outperformed the indy dualplane in torque and horsepower above 3500. below that the indy dualplane was the best performing. it was about 80 ftlbs higher in torque, until 3500.

i use three of the 337,s. they will fit under the stock hood. they also take alot of port matching to match the max wedge ports. i kept the dualplane on one of my 500" motors. it is in a heavy 68 charger that is 100% street driven. i like the extra torque down low. i think the indy dualplane is the best one made...

your pump gas motor is making alot of power . for all of mine to make 700 hp, they needed 13.1 cr and a solid roller 272/276 @.050"-650", carb 1000cfm........