I get about about .65-.7 bar (~65-70 kPa) at idle. When the car is off, the atmosphere reads in at 1.011 bar (~101 kPa), which I believe is correct. I have a slightly high idle too (+100 to 150 rpm) and my brakes are really hard to push (almost no booster help). I've checked all of the hoses and nothing seems to be leaking. I also plugged the booster hose (to make sure the booster wasn't leaking) and it didn't change. I adjusted the valves and had the same result. I have a cam similar to a gm847, so I shouldn't really have any vacuum problems. I had brakes and a decent idle at one time with this new setup. What else could be my problem? I appreciate it guys.

Benji

 

Anyone have any suggestions? I'm almost ready to drive the car, just want to get this figured out before I license it.

Benji

 

did you figure it out???

 

why would you think you wouldnt have vacume issues with the 847... its a pretty big cam for stock ci
is it tuned? whats it idleing at?

 

Of course I'm going to have less vacuum, but not the amount that I am getting. It is tuned (still on starter tune from Joe O) and it is idling around 900 rpm. I talked to Joe Overton and he told me to add some timing and lean it out a bit at idle and it should bring the vacuum back around where it should be. I bought a new brake booster, so the brakes work now. I'm going to mess with it when I get some time and I'll let you guys know.

 

ok i was getting the impression you figured you would have stock vacume lol

yeah a little tuning will bring the vacume back up.
i was running a similar cam and was getting about 65-70 kpa at 900 before i tuned. got it to about 45-55 after.
basicly gave it a decent amount of timing and richened it up to 13.7(closed loop tune)

at idle i was seeing 17 to 1 afr

 

I'm going to try adding some timing and hope that brings the MAP back where it should. I'm reluctant about leaning it out at first because it will lean out when the MAP gets back to where it's supposed to be. I'll toy with it and let you guys know.