what would be the best gear for small block in the 1/4 mile running a 350 small block chevy with about 400 HP with 350 turbo  

There's so many factors:Need to know rpm power range,tire diameter and stall converter flash.There's more than this ,one way is to make some passes and see what rpm you are at when you cross the line.If power range is from 3000 to 6000 lets say,you want at least 5800 or more when you cross.With a 3 speed auto shift about 200 rpm above your rpm range,the gear spread is why.A 6 speed auto it's not as important because   when it upshifts there's less rpm drop between gears compared to yours.Tell us more about your 350 heads,cam etc and stall flash.Lets see how much we can help you.  WIEDER  

Thanks for getting so soon heres what ive got so far 350 chevy bored .030 over a set of 2.02-160 aluminum patriot heads 64CC 5 angel valve grind up to 575 lift changed springs to comp cam bee hive springs holly 750 3/8 roller rockers with a mutha thumper roller cam 3500 stall wiend intake rpm range 2500-6200 10:50:1 pistons chevy X rods valve lift is 531-517 hei electronic dist hopefully this helps also 3 inch exaust this is in a 1967 camaro hope this helps im just trying to put something togather to go down the drag strip and have fun hopeing this combanation works still need to work on gearing and tire size so anybody reading this any and all information would be great
Thanks  

With this information my guess is 4:10 w/26" tires,your 3500 stall seems to much a 3000 flash stall would match cam better and also less slippage at cross line. That stall you have is grabbing to far up your rpm range to get full use of cam.With traction this combo my guess is around in the 12's.Anybody else? Do you have subframe connectors?  WIEDER  

yes i do have sub frame connectors Thanks for the stall information I can change that.Is the carbaration enough or is there a better set up
thanks  

Hook up va. gauge and observe if you have less than 1" of vacuum when your're going thru the gears at full throttle, if so you have enough carb.A double pump w/ mech. secondaries will work with a 3000 stall which is a combo I had at one time.A victor jr single plane will pull harder after the 1/8 mile mark.If you have a stock rear suspension and rear end keep a eye on it. Geddy Up!  WIEDER