Manifold Vacuum Advance with Sniper EFI Progressive Linkage

[MIDEVIL214]

I want to install the progressive throttle linkage on my Sniper system. This renders the ported vacuum source useless since Holley put it in the secondaries. I can run manifold vacuum to the distributor but have read conflicting comments on doing so with my DUI HEI-style distributor. I found one post where the manufacturer said manifold was preferred and another where they said start with ported unless you have an aggressive cam.

I have a mild 302 with a basic performance cam. The distributor was set up at 26 deg. all in by 3k rpms.

 

[DirtDonk]

You can probably try it to see. The EFI "should" compensate and lower the idle back to it's intended rpm no matter what vacuum the distributor is seeing.
You can do that with a carburetor too of course, but as you've heard it can be a bit finicky. I've run engines both ways, and both ways have been used by factories to good effect. But without the other controllers (temp switches, switching valves, computers, etc) I've found the ported vacuum to be more tuner friendly than full vacuum about 90% of the time.

Since it would probably cause more trouble than it's worth to reconfigure the throttle body, or go back to non-progressive linkage, I say give it a try and see how the computer feels about it.

paul

 

[MIDEVIL214]

The progressive linkage swap is very simple and should only take a few minutes. I can also adjust the mechanical idle/IAC as needed if the manifold source bumps things out of wack.

 

[DirtDonk]

Wasn't worried about the difficulty of swapping the linkage, so much as concerned it might not leave you as happy with the way it feels on the pedal.
Did you start with the progressive right off the bat, or did you drive it a bit with the original linkage? Heard too many times that it's too sensitive and that the progressive is MUCHO better.
But if it's an option on the table, then by all means give it a try.

Paul

 

[MIDEVIL214]

I've got about 100 miles on the standard 1:1 linkage. It's not insanely jumpy off the line and my throttle feel is fairly stiff. I attribute those to 37s on beadlocks and the extra helper spring I had to put on my AOD TV linkage to keep the lever from creeping forward.