[trevor]

I bought a Carter AFB 625 cfm carb. for my 302 Ford V8, and the front has two ports: One for timed vacuum and the other regular vacuum. These two ports are for the distributor vacuum advance. The instructions say a dist. with timed vacuum will have low vac. at idle. I have no way to test. I bought a 1985 Mustang distributor to replace the EFI dist.

thnaks for the help - hopefully

 

[Automan]

One port will have vacuum at idle and one will not. You will need to use the port that does not produce vacuum at idle. Some old Buick/Olds. motors used the other port because of the mechanical advance set up using the vacuum at idle to pull timing out. Hope this helps.