J heads upgrade

perfacar said
ok, port velocity and shape are everything, port speed fills the cylinder, not valve size!! as for power, we have tested 2.02 and 1.88 valves on real flow bench. the 1.88 has more port velocity, vs the 2.02. flow is close. the X head was designed for 2.02 valve, the others were designed for 1.88 valve. now, to compare power, in stockers, the 1.88 headed engines are as fast as 2.02 headed engines. some exceptions are there. Chevrolet, went to 2.02 valves years ago. it was a marketing ploy! we tested a chev head with 1.94 and then he opened up bowl , installed 2.02 valve and retested, flow and velocity loss. imagine that!! valve type and seat angles are important to flow gains. I realize you can't brag on 1.88 valves. 2.02 , you can. lol. BTW, a 1.88 valve 340 runs to 7300 rpm in traps, doesn't lose power. 283 chev super stockers, with 1.75 valves run 9200 RPM. no power loss.

This isn't stock where you're stuck with rules. I don't know about anyone else...but in my 4 spd car, I'm already going through 3500 rpm before I'm halfway through the pump shot. A 3.91 4spd 340 is into 6000+rpm real quick...smh A bunch of people who like to argue and talk garbage to others while preaching the mopar bible and using it to verbally backhand people meanwhile ignoring the most basic and obvious example that mopar gives...the 340. Smh Now which years did the factory 340 have more hp ? the 2.02 or 1.88 Were in which years? You talking about port velocity and 340's but using chevys as examples with valve head diameters. What are port volumes of a chevrolame sb again. Use whatever valve you want and build the motor and gear around it to make it work and prove a point, to each his own.