Pulling only 6lbs of Vaccuum
07-01-2008, 03:54 PM
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Car: 1989 Iroc Z
Engine: 496 BBC
Transmission: th400
Axle/Gears: 4.11
Pulling only 6lbs of Vaccuum
I just did a motor swap in my 92' Camaro RS to a 358. I have an edelbrock performer rpm and a comp xr270. the intake is only making 6lbs of vaccuum for the brake booster. normal is around 24-30. what could be the problem?
07-02-2008, 08:33 PM
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Car: '88 Iroc, '91 RS, and a '70 RS
Engine: 5.7 TPI; 5.0 TBI; ZZ4/T56 on the ag
Transmission: A4, A4, slated to be a T56
Re: Pulling only 6lbs of Vaccuum
Too big of a cam/engine combo. Look into an electric vacuum pump and reservoir to hold more vacuum.
Ed
Ed
07-02-2008, 09:49 PM
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Car: 1986 iroc z
Engine: vortec 383
Transmission: th350
Axle/Gears: 3.73 moser 12 bolt true trac
Re: Pulling only 6lbs of Vaccuum
what is the duration of that cam? I doubt its too big.
07-03-2008, 08:42 AM
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Re: Pulling only 6lbs of Vaccuum
That's the same cam I'm running and have at least 15" of vacuum at 750 RPM idle and no problems with my power brakes. You have a bad leak somewhere. Maybe you're brake booster is busted, or your vacuum gauge is. At 6" of vacuum, the engine will be running like total crap.
07-03-2008, 12:45 PM
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Car: 1989 Iroc Z
Engine: 496 BBC
Transmission: th400
Axle/Gears: 4.11
Re: Pulling only 6lbs of Vaccuum
I did realize that we had a port used for cruise control but we took cruise control out. So thats 12" of vaccumm leaking.. But do you think theres more to it? * and the motor does seem to run rough
The cam is a Comp XR270
Intake is Performer RPM
The cam is a Comp XR270
Intake is Performer RPM
07-04-2008, 07:25 AM
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Re: Pulling only 6lbs of Vaccuum
Yes, that's the same cam & intake I'm running.
Are you sure all the unused ports & intake are plugged? If so, then you have a cracked hose somewhere.
Are you sure all the unused ports & intake are plugged? If so, then you have a cracked hose somewhere.
07-05-2008, 07:37 AM
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Car: 1989 Iroc Z
Engine: 496 BBC
Transmission: th400
Axle/Gears: 4.11
Re: Pulling only 6lbs of Vaccuum
We did degree my camshaft 2 degrees retarded. I'm not sure if that would make a vaccum difference? It makes a top end difference though 
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