Posted by bobbyford72 (172.167.176.80) on January 03, 2001 at 15:22:20:
What are the benefits, if any, to a dual diaphram vacuum advance on my 302 '71 Comet GT, as opposed to a single unit? I think I am having a problem with the dual and was wondering if a single unit bolts right up in its place. I understand the ported vacuum side (carb) advances timing upon acceleration and the manifold vacuum side retards it during idle and deaccelaration. Was this a smog type item? Would just one soure of vacuum (single unit) be more reliable? Any thoughts? Thanks in advance for opinions and corrections.