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Vacuum Advance Port

Posted By: ChrgrCuda

Vacuum Advance Port - 10/01/13 12:34 AM

Hey Guys

I just got my ThermoQuad back from Scott Smith at Harms Auto and I'm very pleased. However I'm trying to figure out the correct port to plug in to the carb from the vacuum advance. I've played around with mixed results, just thought I'd ask the experts around here for some advice.

Thanks,
Darren
Posted By: 340SHORTY

Re: Vacuum Advance Port - 10/01/13 01:06 AM

The port that doesnt have vac at idle...
Posted By: ChrgrCuda

Re: Vacuum Advance Port - 10/01/13 01:17 AM

That's what I have it hooked to. Looks like I'm in the right direction. Thanks!
Posted By: hp383

Re: Vacuum Advance Port - 10/01/13 01:56 AM

Quote:

The port that doesn't have vac at idle...




You want no advance at idle, so the ported vacuum signal is the one your after.
Posted By: ChrgrCuda

Re: Vacuum Advance Port - 10/01/13 02:10 AM

Yes sir, that's what I have it hooked to. Now about to try adjusting the vacuum advance. Is it adjustable and which way do I turn it for more advance?
Posted By: hp383

Re: Vacuum Advance Port - 10/01/13 02:20 AM

Some of them are. I think it requires a special tool? I personally have never messed with one.
Posted By: 340SHORTY

Re: Vacuum Advance Port - 10/01/13 03:30 AM

The little screw in the vac pot adjusts WHEN the advance comes in,,, not the amount of advance. The advance is controled by the weights and the little springs...
Posted By: ChrgrCuda

Re: Vacuum Advance Port - 10/01/13 04:08 AM

Got it, thanks Shorty. Which way controls how fat it comes in, clockwise or counter?
Posted By: Magnum

Re: Vacuum Advance Port - 10/01/13 03:48 PM

Manifold vacuum is only out voted here on Moparts. It is not the incorrect port.

It has some advantages, just like ported.

This is one method to have big numbers at idle AND light throttle cruise, which equals better mileage. That's how many computerized cars run.
Posted By: Golden-Arm

Re: Vacuum Advance Port - 10/01/13 08:21 PM

um, what?
Posted By: hp383

Re: Vacuum Advance Port - 10/01/13 10:31 PM

Quote:

um, what?



Whew... I thought maybe I was the only one lost on that.
Posted By: 340SHORTY

Re: Vacuum Advance Port - 10/01/13 10:44 PM

Quote:

Got it, thanks Shorty. Which way controls how fat it comes in, clockwise or counter?





IIRC counter clockwise allows the advance to come in sooner, clockwise delays it..
Posted By: Magnum

Re: Vacuum Advance Port - 10/02/13 05:04 AM

Quote:

Quote:

um, what?



Whew... I thought maybe I was the only one lost on that.



A mild engine like to idle at more than 10 deg. 10 is the number most of us are stuck with due to starter kick back. Manifold vacuum advance is one way to achieve higher advance numbers during idle.

I hate to mention it here on "the old car forums" but idling at 10 degrees is not seen on fuel injected cars. Switching from ported to manifold vacuum advance is another way to achieve timing maps similar to todays cars.

Timing while cranking will be the same, total will be the same, partial throttle will be the same, just more timing during idle.
Posted By: 340SHORTY

Re: Vacuum Advance Port - 10/02/13 05:33 AM

UMMMMMMMM you better check out the timing specs on the TBI engines...
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