[Jeff Chambers]

An E-cam generally will produce in the neighborhood of 15 in-hg at stock idle and 10-degrees base timing, a little more as the idle is increased towards 1000rpm. As others have said, removing base timing will affect idle and hence vacuum at idle. Have you checked your actual base timing? With the 331, load calculation by the computer will be off a little which will affect things a bit. It really sounds like you need to have the car tuned by a professional to bring the combination together and get the best all around performance.