New Member. Some questions please.

[Danny Cabral]

I was reading that you recommend hooking the vacuum advance to full manifold vacuum. Is this correct for non-ECU control timing?

Yes, I almost always recommend "full manifold vacuum" for vacuum advance distributors. However, sometimes a radical camshaft can fluctuate the manifold vacuum too much, and exacerbate an erratic idle. Of course, the entire distributor centrifugal and vacuum advance curve needs to be properly modified. Another benefit of EFI (easily programmed fuel & ignition curves).

I thought vacuum advance was for cruise only, for better fuel economy.

Vacuum advance should be connected to full manifold vacuum; not ported.
8°-12° of vacuum advance is the typical limit (some canisters are adjustable).
The (ported) timed spark port is only for emissions/EGR engines (LINK).

Could running full vacuum at idle cause the engine to run on when switched off?

No, it actually helps prevent dieseling/run-on: http://www.badasscars.com/index.cfm/...prod/prd94.htm (Read 4th paragraph.)

[knightrider]

OK great, so is 15° initial-static (non-vacuum advance), then add vacuum advance, so total idle timing will around 25°?
Just read most of that article. Good read, thanks. Looks like I might need a different vacuum advance unit. I will check what vacuum I have at idle. Cheers.

After reading this, am I best to leave the vacuum advance off, until I sort out the rich idle? The more advance at idle, only helps if it's running leaner-better? Cheers.

[Danny Cabral]

OK great, so is 15° initial-static (non-vacuum advance), then add vacuum advance, so total idle timing will around 25°?

I don't know anything about your engine or camshaft specs, so I can't recommend anything.
http://forums.holley.com/showthread....e-Tuning-Notes (Read "Ignition Timing Advance")
Vacuum advance has nothing to do with WOT timing, because there's no vacuum at WOT.

After reading this, am I best to leave the vacuum advance off, until I sort out the rich idle?

That's fine. I believe the solution to your excessively rich AFR, is in the base calibration. See post #9.

[knightrider]

OK, I'm aware that vacuum advance doesn't work at WOT, and I'm not asking what initial I should run. Rather does the vacuum advance timing go on top of my initial timing? And I think it will only help, once I sort out the rich-flooding idle. Cheers.

[Danny Cabral]

Rather does the vacuum advance timing go on top of my initial timing?

Yes, it's added to the centrifugal timing advance (at idle, cruise and other vacuum conditions).

And I think it will only help once I sort out the rich-flooding idle.

Yes.

[knightrider]

Hi Danny. Ran the engine again, going a little better, still cutting out, slow idle. The IAC Position is always at 30%. Shouldn't it go to 100% if the engine is going to stall, to try and maintain the correct idle speed? Idle drops as low as 500 rpm, IAC still at only 30%. Target idle is 900 rpm. Cheers.

Sent from phone, forgot that did TPS AutoSet again, it's now working still idling slow, rich & stalls, but the IAC did go to 100% to try to keep the idle. Starting to frustrate me now. Cheers.

Hi Danny. Can you tell me if I adjust the idle screw multiple times, and reset the TPS each time, so it reads 0%, how do you know where the throttle is in relation to factory settings? Cheers.

[Danny Cabral]

Sent from phone, forgot that did TPS AutoSet again, it's now working still idling slow, rich & stalls, but the IAC did go to 100% to try to keep the idle.

That's because the idle TPS Position wasn't at 0%, hence activating the IAC Hold Position.
http://forums.holley.com/showthread....8315#post48315 (Additional Information)

Can you tell me if I adjust the idle screw multiple times, and reset the TPS each time, so it reads 0%, how do you know where the throttle is in relation to factory settings?

No, but it doesn't matter, because after installation, it will be a different setting for every engine.
http://forums.holley.com/showthread....neral-IAC-Info (IAC Information)

[knightrider]

OK thanks. Not sure what to try next, may try opening the throttle set screw some more. I did even try setting the RPM activation to 2000 rpm, made no different to the idle. So I changed it back to 0. It's acting like the MAP sensor isn't working, or reading very low vacuum. Idle AFR goes as low as 10:1 before stalling. Cheers.

[Danny Cabral]

I did even try setting the RPM activation to 2000 rpm, made no different to the idle. So I changed it back to 0.

What are you referring to here? You'll have use the proper Holley EFI software terminology.

[knightrider]

Hi Danny, it's on page 31, 32.2.4 RPM activation. I guess it's only for manual tuning below the set rpm. Cheers.