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Old 08-19-2008, 01:30 PM   #1
RPJOHNSON2
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Need More Vacuum For Disc Brakes

I have about 17 lbs of vac. going to the booster from the a 1 port valve from the back of the intake and about the same from a back of the carb. how can i get more vac.Im working on a 72 blazer 4x4 with a/c

Last edited by RPJOHNSON2; 08-19-2008 at 01:34 PM. Reason: more info
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Old 08-19-2008, 02:09 PM   #2
Musclerodz
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Re: Need More Vacuum For Disc Brakes

What cam is in the motor? What booster do you have? Why do you think you need more vaccum?

Mike
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Last edited by Musclerodz; 08-19-2008 at 02:10 PM.
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Old 08-20-2008, 11:37 PM   #3
RPJOHNSON2
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Re: Need More Vacuum For Disc Brakes

i have a mild street cam size unknown i just put a delco booster on it only showing 18 lbs of vac. the pedal is still going almost to the floor after new brakes and master cylinder and booster
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Old 08-21-2008, 07:14 AM   #4
cparman
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Re: Need More Vacuum For Disc Brakes

low vacuum problems result in a very hard pedal ( no assist )
not low pedals. I would recheck adjustment at rear brakes, and then rebleed system. 17-18 inches should be enough to make that system work fine

Last edited by cparman; 08-21-2008 at 07:14 AM.
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Old 08-21-2008, 08:35 AM   #5
Huck
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Re: Need More Vacuum For Disc Brakes

I went crazy for 2 years trying to get my 72 brakes working well. Tried the 3/4 ton booster etc. Then went back to square one--replaced wheel cylinders, calipers, shoes/pads, master cylinder--but the real issue is to bleed the front and rear brakes really well making sure to pull or push the pin in the proportioning valve when you bleed. Once I did that the right way (can't remember to push or pull the pin??)---the brakes work super--will pop you into the windshield if not belted in. My Blazer has a performance Cam with edelbrock intake etc. pushing about 16-18 inches of vacuum. Huck
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Old 08-21-2008, 10:02 AM   #6
RPJOHNSON2
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Re: Need More Vacuum For Disc Brakes

Thanks For All The Info. I Will Definitely Try That.

Thanks
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