where in vaccum should my gauge read at idle
May 26, 2006, 10:54 AM
#31
Originally Posted by EvoRicer
Im in NorCal, my Vac at idle is 19-21 inhg. Is that normal for me or is something wrong? I have a Defi BF boost gauge. Also it spikes to around 24-25 inhg when I let off the gas...normal?
May 26, 2006, 02:27 PM
#32
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Originally Posted by Liquid-R1
When I put in 272/272's it went to about 13-15... WHen the A/C on, it goes to 10...
Oct 5, 2007, 11:33 AM
#38
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I had the Megan Manifold and the Megan o2 housing just installed and I also have the Cosworth Cams. I am using the Prosport Premium gauge and Mine reads around 10-12 is that normal? Before it used to read around 18-20
Last edited by Evo2wIsh4; Oct 5, 2007 at 12:16 PM.
Oct 5, 2007, 01:01 PM
#41
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I don't know if you are running a vac line through the firewall to the gauge but sometimes they get pinched at the firewall and will expand enough to read right at boost but not in vac. I would just double check that first.
Cams with play with vac at idle as well big time depending on how hairy they are.
Good luck,
~Tom
Cams with play with vac at idle as well big time depending on how hairy they are.
Good luck,
~Tom
Oct 5, 2007, 01:10 PM
#42
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Mine is a digital gauge. So I am not sure whats going on. I re-ran all the vacuum lines and put brand new ones and still the same reading. And It happened after the o2 housing and manifold install.
Oct 5, 2007, 02:32 PM
#44
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its provably is the combination of everything. I am going to double check it on sunday when I got get the car Dynoed and tuned. They are going to gook up their data logging equipment so lets see if they match.
Oct 5, 2007, 02:51 PM
#45
Interesting...but..vacuum doesn't fluxuate with altitude unless the idle speed is reduced......or mixture changed (;-), more likely the issue) I think that would be paramount to saying thinner air moves slower then thicker air...( dont think physics allows that) could be different vacuum in stock cars/cams as well...depending on cam timing, hence the need for cam gears...given the opportunity to tune a car paying attention to the vacuum alone...tune to the highest vacuum for a given idle speed... back in the day, thats the way you tuned for idle richness...by vacuum, going for the highest vacuum pulled by adjusting the mixture screws then idle..