I just put in my new VDO Vacuum/Boost gauge on my 87 GN. In Park/Idle I'm reading ~19"/HG.
Searching around the site here I found a normal
reading should be ~15" and other posts show readings of ~13".
My car has a stock cam. Is this a good sign for me or what? I was expecting it to be lower.
"Normal" on most of the almost stock GN's I have checked, it has been 17-19? Would say you have a "good" sign.
Courious where or who said 15" is normal? A 13 reading must be a very wild cam for a turbo motor.
That low reading should occur in drive with the brakes on.
Nick:
I got the info from the buyers guide here on the site..
In the section "Just Before start up.."
it says:In Park, a reading between 12" to 15"Hg with an inch of "float" is normal
http://www.gnttype.org/general/buyguide.html
post:
http://www.gnttype.org/discus/messages/17/416.html?998801580
Frank:
Thanks, I will see what it reads that way..
It's generally true ... anywhere from 12-19" Hg is typical for a street car. The generality comes from all the different cams out there and the differences in altitude.
I found that I lost about 2" Hg when moving from 1000 ft above sealevel to my current 5500 ft.
With a 208/202 cam and 1.65 roller rockers I got about 16-17" Hg in Nebraska and get about 14-15" Hg now.
My car has a stock camshaft in it. It idles at 700RPM in Drive and 775RPM in Park. It gets about 15" vaccum in Drive and about 18" in Park.
19" is probably normal for a stock chip (650rpm in Drive and 700rpm in Park, if I remember correctly) on a stock car with a healthy engine (in Park). A car that gets 15" or less in Park either has an aggressive camshaft, a vacuum leak, or a chip with a high idle speed setting.
If my car got 19" in Park with a stock cam, I'd be happy... Hope this helps.