power brake vaccuum line - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bob1967 · 12-04-2007, 08:36 PM

I just put a disc brake conversion on my truck and power brakes. Is it better to run the vaccuum off the intake or the carb. And have any of you ever had a master cylinder drain the back resevior into the front and over flow the front resevior. This has been a head ache of a project nothing has gone right

. Any help is greatly appreciated. Thanks

C10-Driver · 12-04-2007, 09:22 PM

I'm not positive but I would say you should connect to a vacuum source on the intake.

webfoot · 12-04-2007, 09:26 PM

Manifold vacuum. Carb has little or no vac at idle.

Husker · 12-04-2007, 09:36 PM

When i did mine i took a plug out right behind carb (V8). Also I had more problems converting to disc brakes it was a Pain. But I am done now.
About the resorvoir problem did you bleed the MC before you hooked up the lines. Good Luck
Ron

bob1967 · 12-05-2007, 06:58 AM

Thanks for the responses. Husker we bled the master, proportioning valve and the brakes, still pushes out. we thought after the proportioning valve we had it fixed started the truck and it overflowed and the brake pedal went down and didn't come back up. Think now it is headed to the shop so they can get it done.

**truckdude239** · 12-05-2007, 07:15 AM

its bad master cylider it is leaking internally

Tx Firefighter · 12-05-2007, 07:19 AM

Fellas, hook your vacuum connection to the carb. That's where the general connected them from the factory. That way you get full manifold vacuum from a nice big port.

centsless · 12-05-2007, 12:40 PM

The vacuum can be hooked to the large port in the rear of the carb. It is beneath the throttle plate, so it is manifold vacuum. It can also be hooked to the manifold port where the auto trans modulator is hooked by changing the fitting. Either place is acceptable. As far as the master cylinder, replace it if it is transferring fluid between reservoirs.

Bus Ted Knuckle · 12-05-2007, 01:56 PM

They are hooked to the bottom rear of the carb from the factory! but some carb bases do not have the tapped boss on the rear.

Hooking to the manifold will work fine too though.

12-04-2007, 08:36 PM	#1
bob1967 Registered User Join Date: Nov 2007 Location: peaster, texas Posts: 71	power brake vaccuum line I just put a disc brake conversion on my truck and power brakes. Is it better to run the vaccuum off the intake or the carb. And have any of you ever had a master cylinder drain the back resevior into the front and over flow the front resevior. This has been a head ache of a project nothing has gone right . Any help is greatly appreciated. Thanks

12-04-2007, 09:22 PM	#2
C10-Driver Chevy Truck Addict Join Date: Aug 2006 Location: Kelowna, BC Posts: 1,176	Re: power brake vaccuum line I'm not positive but I would say you should connect to a vacuum source on the intake. __________________ . 1970 Chev C/10 SWB, 355 SBC, 700R4, 3.73 Posi, Air Ride (Click to view Build Thread) (SOLD) 1978 Chevy C/10 SWB 1970 Pontiac Lemans .

12-04-2007, 09:26 PM	#3
webfoot Registered User Join Date: Nov 2007 Location: Hermiston, OR Posts: 947	Re: power brake vaccuum line Manifold vacuum. Carb has little or no vac at idle. __________________ *Running in place gets you nowhere fast.* -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC. Last edited by webfoot; 12-04-2007 at 09:27 PM.

12-04-2007, 09:36 PM	#4
Husker Registered User Join Date: Dec 1999 Location: Mid NE USA Posts: 2,212	Re: power brake vaccuum line When i did mine i took a plug out right behind carb (V8). Also I had more problems converting to disc brakes it was a Pain. But I am done now. About the resorvoir problem did you bleed the MC before you hooked up the lines. Good Luck Ron __________________ Member #111 68 C-10 Daily Driver 70 4x4 Project 76 Jeep CJ-5 Help Support the Board: http://67-72chevytrucks.com/vboard/payments.php He who knows nothing is closer to the truth than he whose mind is filled with falsehoods and errors. Thomas Jefferson

12-05-2007, 06:58 AM	#5
bob1967 Registered User Join Date: Nov 2007 Location: peaster, texas Posts: 71	Re: power brake vaccuum line Thanks for the responses. Husker we bled the master, proportioning valve and the brakes, still pushes out. we thought after the proportioning valve we had it fixed started the truck and it overflowed and the brake pedal went down and didn't come back up. Think now it is headed to the shop so they can get it done.

12-05-2007, 07:15 AM	#6
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,236	Re: power brake vaccuum line its bad master cylider it is leaking internally __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

12-05-2007, 07:19 AM	#7
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: power brake vaccuum line Fellas, hook your vacuum connection to the carb. That's where the general connected them from the factory. That way you get full manifold vacuum from a nice big port. __________________ I'm on the Instagram- @Gearhead_Kevin

12-05-2007, 12:40 PM	#8
centsless sufficiently talented fool Join Date: Jun 2006 Location: Forest Hill, MD Posts: 2,231	Re: power brake vaccuum line The vacuum can be hooked to the large port in the rear of the carb. It is beneath the throttle plate, so it is manifold vacuum. It can also be hooked to the manifold port where the auto trans modulator is hooked by changing the fitting. Either place is acceptable. As far as the master cylinder, replace it if it is transferring fluid between reservoirs. __________________ "it's impossible to be surrounded by idiots when you are part of the circle" 2003 Suburban 2002 Pontiac Montana 1981 Corvette 1966 Impala Convertible Click here to support the board

12-05-2007, 01:56 PM	#9
Bus Ted Knuckle Son of a gun Join Date: Jan 2007 Location: Hot Springs, Arkansas Posts: 1,636	Re: power brake vaccuum line They are hooked to the bottom rear of the carb from the factory! but some carb bases do not have the tapped boss on the rear. Hooking to the manifold will work fine too though. __________________ Bill BEATERS ARE NEATER Last edited by Bus Ted Knuckle; 12-05-2007 at 02:36 PM.



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