[Hokie1984]

I know this has been discussed before, but I am struggling to get my timing set. I thought I slipped the outer ring on my harmonic balancer, but that looks fine (thank you Jeff). Anyways, I am setting up my new EFI using the ported vacuum for the distributer and it just doesn't respond correct. It tells you to set the timing at 5 degrees with the vacuum disconnected. I am questioning why you would need to disconnect the ported vacuum because at idle it is effectively 0 inHg meaning it really has no impact on the advance. I checked the ported vacuum and sure enough it you rev it up, it defiantly actuates.

I looked in the shop manual, and it is silent on which vacuum source to use on non-AIR L6 cars. Interestingly, on V8 cars it says "The vacuum advance is connected directly to manifold vacuum so there is full vacuum advance at idle." So I am questioning, should I also connect to full manifold vacuum. I don't remember how much vacuum existed on my Quadrajet but I do recall the timing shifting a bit when it was disconnected. Any ideas?

[sprintbird]

Your mistake is following the initial timing indicated in the Pontiac manual. Gasoline is completely different today than in 1966. You want to be 5 to 7 degrees on top the 5 before TDC. So 10 to 12 degrees before top dead center is a good starting point. Don’t switch vacuum sources just yet. See if your EFI likes that much better.

[Hokie1984]

Ok that makes me feel much better. I am 12 to 15 degrees currently and it runs infinitely better. At that timing my vacuum is good and it runs much smoother. I am still letting the EFI learn at this level before I start tweaking the accelerator pump settings.

[sprintbird]

Great to hear! You are on your way then. Good luck!