Vacuum questions

95gtdude

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May 18, 2005

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Jul 20, 2007

#1

• Jul 20, 2007

• #1

I put a Vacuum gage on the beast today and it ran at 11 inches Hg. now from what I've been told that is way too low. I took the PCV out and pluged it up and unpluged to see if it would change the vacuum and it wasn't that much of a change. Does any body know where it is suppose to run exactly and how I can get it there?

 

Bosko5.0

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May 18, 2006

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longwood, FL

Jul 20, 2007

#2

• Jul 20, 2007

• #2

95gtdude said:

Does any body know where it is suppose to run exactly and how I can get it there?

Click to expand...

Where whats suppose to run???

Usually with a different cam you will get lower vaccum readings.

when you take the readings do it stay at a constant pressure or does it bounce around?

 

95gtdude

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May 18, 2005

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Jul 20, 2007

#3

• Jul 20, 2007

• #3

It bounces around a bit when first starting it but after warming up til stay right at 11in Hg with little flux

 

Yellow302

Member

Mar 2, 2003

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NJ

Jul 20, 2007

#4

• Jul 20, 2007

• #4

What I did since i tune my own is reduce the amount the IAC is alowed to open. They sell peices of metal that are called restricter plates.

at idle im up to about 12-14 from 8-10 vacum. Once im driving anything above 1k im at 18-22 vaccume.

You could also try to get some cheap gasket sheets and trace the one on there and make a smaller opening. cheapest way to go.

Make sure you run a cap on your oil fill neck if you pcv valve is connected to your intake. If not cap your pcv was acting as a leak when i had the breater and pvc connected.

 

Stanger007

Founding Member

Sep 26, 2001

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Baton Rouge, LA

Jul 20, 2007

#5

• Jul 20, 2007

• #5

Stock cammed engines run 18-22. You've got the stage 1 cam which has a bit of a lope but I would think that you would be much closer to 18-22 than 11.

Check for vacuum leaks - did you plug all the holes in the trickflow intake? Seems like there were a million of them I had to plug.

Wes

 

final5-0

Mustang Master

Apr 6, 2003

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DFW Texas

Jul 20, 2007

#6

• Jul 20, 2007

• #6

Heck Fire

Now you got me wondering

I ain't had a v gauge on any of my combos
since I got back in this hobby in 97

Its still up in the attic somewhere

Wonder if it still works

Grady

 

HISSIN50

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Jul 20, 2007

#7

• Jul 20, 2007

• #7

I agree - something is very wrong Tell us exactly how the readings vary (fluctuate), as you can make inferences from exactly what the gauge is doing.

You gotta love the vac gauge (they really are very useful).

 

95gtdude

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Jul 21, 2007

#8

• Jul 21, 2007

• #8

Stanger007 said:

Stock cammed engines run 18-22. You've got the stage 1 cam which has a bit of a lope but I would think that you would be much closer to 18-22 than 11.

Check for vacuum leaks - did you plug all the holes in the trickflow intake? Seems like there were a million of them I had to plug.

Wes

Click to expand...

Yeah as far as I know I have no v-leaks anywhere on the manifold.

 

95gtdude

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Jul 21, 2007

#9

• Jul 21, 2007

• #9

HISSIN50 said:

I agree - something is very wrong Tell us exactly how the readings vary (fluctuate), as you can make inferences from exactly what the gauge is doing.

You gotta love the vac gauge (they really are very useful).

Click to expand...

well like I said it bounces between 11 and 13 inches Hg when starting cold and after warming up it'll stablize at 11 and move just a little (seems to move slightly with the cam lope)

 

HISSIN50

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Jul 21, 2007

#10

• Jul 21, 2007

• #10

95gtdude said:

well like I said it bounces between 11 and 13 inches Hg when starting cold and after warming up it'll stablize at 11 and move just a little (seems to move slightly with the cam lope)

Click to expand...

Speaking for the oscillation, this kinda sounds like you have a miss or an issue with a valve.

 

95gtdude

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Jul 25, 2007

#11

• Jul 25, 2007

• #11

So what do I do to fix the problem?

 

HISSIN50

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Jul 25, 2007

#12

• Jul 25, 2007

• #12

95gtdude said:

So what do I do to fix the problem?

Click to expand...

Because vacuum diagnostics are tough to convey over a keyboard, I did some digging and think this link might help.
Otherwise, I'd be doing a leakdown test.

Good luck.

 

95gtdude

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Jul 27, 2007

#13

• Jul 27, 2007

• #13

HISSIN50 said:

Because vacuum diagnostics are tough to convey over a keyboard, I did some digging and think this link might help.
Otherwise, I'd be doing a leakdown test.

Good luck.

Click to expand...

Thanks Hissin!