I bought a 90yj with the 4.2, it has a webber carb on it but the vaccuum advanced is hooked up wrong. What vaccuum port does the advance hook up to to function properly. I thought it should be hooked up to venturi vaccum or tb vaccum and not mannifold vaccum. its not hooked up to any vac now because i'm not sure where to hook up. Mannifold vaccuum advances the ignition when at idle and as soon as you accelerate it retards timing and backfires through carb.