Hi everyone, I need some assistance on parts interchange. Background: I have the '74 Mav with a 250. I'm trying to restore it to original with my son. The previous owner butchered the vacuum lines and put the wrong carb on the engine. I've got a rebuilt Carter RBS carb and am trying to setup the vacuum lines as original. Problem: I checked today and found that the distributor had been changed also. The distributor that is in it is 38 D7BE 12127 DA 7C 2. My manuals all show a dual port vacuum advance for that year. The distrib on it is a single port with electronic ignition. I called Autozone-I can purchase a vacuum advance for the '74 Mav year for about $25. I have to order it. They can't tell me how many ports it has till Monday. They cross over the '74 year to the following distributors: D3DF-12127FA---Dual port D4DE-12127NA---Dual port D3OF-12127BA---Single port D3OF-12127RA---Single port They can get me a Al Cardone rebuilt distributor #30-2682 for $37, but they won't be able to check on the vac advance ports till Monday. They aren't sure whether it is a points or electronic ignition. They aren't sure whether it comes with a vacuum advance unit or if I have to order it. Question: Can I get a dual port vacuum advance for the distributor that is on it that will work properly for the '74 vacuum emissions system?
The second port (closest to the distributor cap) was used to retard ignition timing. Why would you want to do that? Back in the 70's the first thing everyone did was disconnect and plug the hose to the retard side.
As stated in my first post, I'm trying to restore the car to original. I can understand your question. I know it retards the timing. Was the reason for plugging it because of an engineering defect on Ford's part? In otherwards, was the reason everyone plugged it for a real problem vs. a performance issue?
It was removed for performance reasons. The ignition timing would advance more quickly from idle rpm.
