Vacuum block questions for experts...

[Nashty]

I have to remove the vacuum block and need some advice on the source for some vacuum.

Correct me where I'm wrong here but I believe that this is the order for the vacuum lines starting from the front of the car and going back:

1 - Aftermarket Boost Gauge & Unknown
2 - HVAC & Cruise
3 - Fuel Pressure Reg
4 - MAP sensor
5 - PCV

1 - This goes BEFORE the throttle body blade.

2 thru 5 - All other feeds come AFTER the throttle body blade.

All I'm going to need is a MAP and FPR hookup. Those look to me to be behind the TB blade. I can make a fitting work on the side of the TB or even the plenum.

Question #1
Does it matter that the vacuum port be right at the top of the TB just behind the blade? This is where the air velocity would be highest (lowest pressure) during part throttle. Can this be moved to anywhere where the feed would just read intake manifold pressure like on the plenum?

Question #2
What the heck does that first vacuum line hook up to from the factory? Is it the Charcoal canister?

This car won't need any hookups for the Charcoal canister, HVAC, cruise or PCV.

Thanks,

Roger

 

[gnsrule]

I just went out to the garage to look, but side tracked into working on the car for about 2 1/2 hrs and didnt look at that.
If I remebr , the first one is evap which u dont need.#2 is FP. #3 is egr-optional. 4 is hvac and I think your map sensor, check and run as acordingly.#5 is your pvc obviously.
Run your boost gauge off the hvac line.
Hope this helps

 

[John Larkin]

Hey Roger. I looked at mine.
1 = charcoal cannister, 2 = EGR, 3 = FP (these are grouped on three steel lines)
4 = MAP, 5 = PCV (these are grouped on two steel lines)

I haven't had the vacuum pod off in a long time. I'm thinking it's split vacuum underneath, before and after the throttle blade. I recall two holes in the throttle body under there. Makes sense due to the lines being in two groups.

Hope this helps.

 

[Nashty]

Thanks for the clarification on the first line.

Now about that vacuum hole location. Does it matter where it's at? If it doesn't, I'd like to move it to the plenum. My concern is that the air velocity will be much lower there where the area is larger. The signal will probably not be as responsive. Any problems with that?

 

[Razor]

Why are you doing this?

Vacuum is air thats after the throttle body made by your engine while the blade is closed.

I dont see a benefit.. maybe you could clarify why the extra work.. I'm all ears

 

[XXQUICK6XX]

It's for his GEO mobile probably a interferance issue with the hood he pry wants that stealth look.

Steve

 

[Nashty]

Steve's right, it's for the Geo. And it's not hood clearance, it's cowl clearance, we have a little engine setback you see.

I think I'll just find a new location for the vacuum tap and sh!tcan the vacuum block entirely.

 

[Razor]

All you have to do is punch a hole into the dog house and tap a pipe fitting. Vacuum is measured inside manifold.

HTH

ps..didnt know it was for an engine transplant..

Good luck tho..sounds cool