I just got the book The Advancing Guitarist by Mick Goodrick and for the single string exercises it says to record seven 3 minute modal vamps in the key of C to begin.......would i record each chord related to the major scale mode for 3 minutes each(CMaj7,Dmin7,Emin7 etc..) or something else??? just want to make sure thanks in advance.
I think it means to record each static chord of the major scale for three minutes, then the next and so forth while you play over them using the modal patterns.

I - C Maj - C Ionian.
ii - D Min - D Dorian.
iii - E Min - E Phrygian.
IV - F Maj - F Lydian.
V - G Maj - G Mixolydian.
vi - A Min - A Aeolian.
vii° - B Dim - B Locrian.

It's a method I find highly effective in getting to grips with modal playing.
Thats what I thought he meant just wasnt sure.......the one string improvising with vamps is really a really good idea ive put 2 hours a day into just this exercise and have noticed my improv and ear improving alot .....check this book out!!
yes, a vamp is just a groove on a single chord (of course extremely common in rock and metal. Vamps aregood for practicing modes simply because they free your ears from the complications of harmony so that the character of the mode rings out.