FL Junkie

iTrader: (23)

can anybody who has cammed their car give me a vacuum reading theyve taken? i just want to get a general idea of where it is supposed lie with a larger cam. i get a steady reading 9 inches.

chris93266

iTrader: (5)

I don't have any measurements, but my car has sucky vacuum. I'm going to go with a vacuum canister setup, so my brakes will work like they used to.

FL Junkie

iTrader: (23)

any body

SSpdDmon

iTrader: (10)

If you can convert it, most large cams idle with a MAP reading of 55~65kPa. That means at sea level, they see about 35~45kPa of vacuum.

**edit**If the calculator I found is right, that translates into about 10.7~13.7inHg. (Assumes 101.325kPa=30.006inHg at 60*F.)

How big of a cam are we talking and where are your idle RPMs?

Stroker2112

FL Junkie,

I just experienced a similiar scenario at the dyno yesterday. I continually had a low manifold vacuum reading (9Hg) on coinciding with a lowering IAC reading apon acceleration. We simply reconnected the IAC connector and it fixed the problem right away(must not have been seated fully, it had been re-connected many times during current modifications). The vacuum then read 12+HG and the IAC quickly jumped up into the 80-90s after this. I'm not saying your connector is bad or not connected properly...but it's a quick/easy place to check right away....good luck.

Stroker2112

FL Junkie

iTrader: (23)

well i pulled my whole intake off and the seals look somewhat collapsed so im putting on new ones. i also found on the back, the map sensor seal is a little worn, its just wobbling around on the hole. replacing that as well. the fuel injector o-rings look ok.

i would think that if you have a bad enough vacuum leak you will lose vacuum and get a low reading anyway......right?

for the record its a comp 236 244 .580 on 112. the tuner set my idle at 1k.

GuitsBoy

iTrader: (4)

My mid sized cam usually idles around 58 KPA @ 800 rpm, which works out to be about 12.8" hg. vacuum.