so I bought a 340 longblock from a guy off craigslist who said it was a runner. he kept the intake, carb, and distributor for himself and I still have mine that I took off my 318 about a month ago so I know they are fine. now when I put the motor in i cant get it to idle under 1500 rpm no matter what i do. ive changed the timing a bunch and no change. i know everything is good as i had it running on my 318 so it has to be something in the longblock. i also tried a diff carb and no change. so what in the longblock will make it so i cant get it to idle down? just wondering how far im going to have to tear into this motor and how much this is going to cost me. thanks and love the site!