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Old 04-06-2003, 10:05 PM   #1
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Boost gauge reading 20 vacuum at idle, is that normal??

I always figured this was normal, but then i read a few things and it seems that normal is a vacuum of about 10.....do i have a problem?
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Old 04-06-2003, 10:25 PM   #2
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What does your Zero read with the car off? If it's an Autom
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Old 04-06-2003, 10:29 PM   #3
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If it's an Autometer gauge the needle should be in the box at Zero with the car off.

On mine with the stock cam it idled at around 14 inches and with the E cam it idles at around 10 inches.
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Old 04-06-2003, 11:18 PM   #4
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with the car completely off it reads about 3 or 4 vacuum....but at idle its like 21.....my cam is nowhere near stock, but still i dunno why it reads so high?
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Old 04-06-2003, 11:29 PM   #5
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Sounds like a bad gauge, give Autometer a call, get an RMA and send it back...

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Old 04-07-2003, 12:47 AM   #6
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my guage reads 2or3 with car off, and 20, 21 at idle
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Old 04-07-2003, 12:57 AM   #7
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hmm well at least im not alone...anyone else?
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Old 04-07-2003, 01:04 AM   #8
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The needle should be in the box with the car off. If it is not then send it back.

The zero is flexable within the box to accomodate for atmospheric conditions outside at any given time.
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Old 04-07-2003, 01:08 AM   #9
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not nessesarily, my buddy evlbrd wth a blown 351 reads about 20 at idle
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Old 04-07-2003, 10:21 AM   #10
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my TFS stage1 cam reads 10in. @idle
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Old 04-07-2003, 11:37 AM   #11
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mine reads zero with car off about 11-13 at idle. It should be zero with the car off, sounds like a bad guage to me
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Old 04-07-2003, 11:40 AM   #12
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mine reads 19-20in at idle, but i have a stock cam. (it reads 0 when the engine is off)
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Old 04-07-2003, 12:54 PM   #13
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TFS Stage 1

0" engine off

11-12" engine running
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Old 04-07-2003, 01:33 PM   #14
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Not the same gauge but I have a defective fuel pressure gauge I just sent back that when completely bled down it still reads 20 psi or so. Obviously when fired up my F/P reads 20 psi high. Is this a Pro Comp fluid filled gauge by any chance?

Another vote for send it back.
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Old 04-07-2003, 10:38 PM   #15
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umm its just a regular autometer mechanical boost gauge.....silver on silver. i wonder if its bad, i mean at idle it sits at like 20, but with a real small touch of the pedal it goes to 10 easy, hmm im confused
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Old 04-08-2003, 03:03 AM   #16
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What does it read with the car off?
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Old 04-08-2003, 01:41 PM   #17
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alittle under zero
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Old 04-08-2003, 04:43 PM   #18
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17-20 in. Hg at idle. (850 rpm'S)

0 in. Hg. off

I have the autometer phantom 30 in Hg- 20 psi boost and a stock cam and s-trim.

Please realize that vacuum is dependent on idle rpm's. Lower idle rpm's result in lower vacuum. maybe you're idleing a bit high. Also, It's notmal to see a decrease in vacuum when you rev it up a bit. However, if you're not seeing zero when the car is off, then the gage needs some attention.
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Old 04-08-2003, 06:36 PM   #19
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here it is

normal is 17- 22
normal for the stock cam is 18-21
if you advance the timing, you get more vaccum. mine stays around 20.
you should check for an intake leak or leak in the vacuum tubing to the gauge. auto meter gauges never read right, but if its that far off, i dont think its the gauges fault. my gauge read 14 psi when i was running 17 and it read 20 inches during a heavy deceleration when it should read 25. enjoy.
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