cant get the front up

ok, i wired up my 78, and take in mind i have a 350 and a lot of other weight up front, i have 2 firestone 9210 compressors with 3-5gallon tanks, and i put the front and back valves up in front to keep it all together, now the back valves have the longest way to travel, and when the tanks fill up that shit hops hard, but when i try to get the front up it goes up an inch and thats it, and i have to take it a hit at a time and it took about a half hour to get the front up, i have 1/2" valves so i dont know wut the deal is....i bought a 450 viair yest. and i havent hookt it up, i dunno if that will solve my probs....what is going on here??? any help will seriously be awesome, thanks!