I have a 1979 Bronco with a 400 engine. Next weekend I'm planning to install a Edelbrock 2172 cam & lifters with a Edelbrock 7821 timing chain kit. A mechanic had told me I could get better responsiveness and low end torque if I advanced the timing sprocket 4*. The Edelbrock instructions say not to install it at anything other than 0* and to only advance it only if the cam is degreed with a wheel. Is the cam already advanced or is Edelbrock just covering themselves and their warranty?