Brake booster vacuum - The 1947 - Present Chevrolet & GMC Truck Message Board Network

yoshi · 10-10-2014, 04:58 PM

I've fitted a booster under the cab but don't know where to connect the vacuum pipe to on my sbc350. Can anyone advise? Thanks

Rude Dude · 10-10-2014, 05:05 PM

Intake manifold should have a plug at rear of manifold

yoshi · 10-10-2014, 05:10 PM

Ah I see, that maybe where I thought the fuel was gonna go in. Holley 4 barrel.

OrrieG · 10-10-2014, 06:24 PM

There is a port in the intake runner between the carb and dist. You can get the tee fitting at auto store. Big one goes to the vaccum booster, small to auto trans vacuum modulator if there is one. Dist is feed from port in carb. Big fitting at the back of the carb is for PVC valve from valve cover.

Speedbumpauto · 10-11-2014, 10:15 AM

Most Holleys have a 3/8 port at the rear that will serve vac boosters and/or PCV.

la hi · 10-11-2014, 07:33 PM

I have a 454 with the thumper cam. the engine will not generate enough vacuum to operate the power brake booster.
I mounted the vacuum pump under the cab and the tube from the pump direct to the power brake booster. This pump is electric, noisy, runs a lot, vibrates, and you have to make sure the the electrical connection stays connected.

yoshi · 10-12-2014, 05:06 PM

Is that 3/8 BSP?

la hi · 10-12-2014, 05:10 PM

I am not sure what you mean?

yoshi · 10-12-2014, 05:15 PM

Most Holleys have a 3/8port at the rear that will serve vac boosters and/or PCV.

**mr48chev** · 10-12-2014, 05:15 PM

There are some belt driven vacuum pumps out there designed to go on Diesels in pickups that would adapt easily.

If I was running power steering I'd seriously consider a hydroboost setup and not worry about vacuum.

yoshi · 10-12-2014, 05:16 PM

I'm not running power steering

la hi · 10-12-2014, 05:38 PM

Sorry, I did not read it thoroughly. I used the vacuum pump because my Thumper cam, edelbrock carb and the intake manifold would not put out enough vacuum to operate the power brake booster. The only vacuum I need is for the power brakes and the vacuum pump gets the job done. I do believe that the hose is 3/8" as you asked. The power brake unit is also under the cab and it is a short run. I can not see using vacuum for any function going forward or I would install a vacuum reservoir between the pump and the power brake booster.

OrrieG · 10-13-2014, 01:12 AM

I don't think he is having an issue with low vacuum, just wants to know where the hose goes. Most manifolds, even after market, come with the port I showed. GM sold millions of car using it without any problems. It is where I ran mine under floor booster hose to, works great.

yoshi · 10-13-2014, 01:19 AM

Yeah, I haven't got anything being a project that I've taken over, thanks

yoshi · 10-13-2014, 08:24 AM

The carb is too close to the hole to screw a Tee in there. I might have room to screw an elbow, then the Tee

Highsider · 10-13-2014, 11:38 AM

Quote:

Originally Posted by yoshi

The carb is too close to the hole to screw a Tee in there. I might have room to screw an elbow, then the Tee

Can you take a photo like Orrie's view? I am curious, too.

yoshi · 10-13-2014, 01:06 PM

Best picture I have at the moment

Old Crow · 10-13-2014, 01:46 PM

Yet another reason to hate Holley carbs. Elbow and a Tee it is. Make sure there isn't an open fitting/threaded hole on the back of the carb base plate.

OrrieG · 10-13-2014, 03:03 PM

Or there is plenty of room to put the carb on a spacer plate, would improve fuel delivery too.

yoshi · 10-13-2014, 05:18 PM

I'm gonna put a 3/8 plug in that hole & connect the booster hose to the outlet at the back of the carb on the spacer. I'm also gonna come off a smaller outlet at the front to go to the gearbox.

Russell Ashley · 10-14-2014, 09:00 AM

There's a charcoal filter that goes in the vacuum line to the booster. I've read that you should have one or the gas fumes shorten the life of the booster. They're cheap so not a big expense, and readily available. Here's a link if you are not familiar with what I'm talking about.
https://www.google.com/?gws_rd=ssl#q...booster+filter

yoshi · 10-14-2014, 09:10 AM

I have seen one fitted to a truck & I wondered what it was. That link isn't working for me

**mr48chev** · 10-14-2014, 11:51 AM

It's just a thought but I've had to remove the carb to put a T in that spot when I ran Holley carbs on my truck.

If you don't have an automatic you wouldn't need a T though and an elbow or straight fitting would work.

Russell Ashley · 10-14-2014, 01:53 PM

Quote:

Originally Posted by yoshi

I have seen one fitted to a truck & I wondered what it was. That link isn't working for me

Not sure why the link didn't work, but you will get similar results if you google brake booster charcoal filter.

OrrieG · 10-14-2014, 01:58 PM

Russell Good point, now I need to add it to the to do list..

10-10-2014, 04:58 PM	#1
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Brake booster vacuum I've fitted a booster under the cab but don't know where to connect the vacuum pipe to on my sbc350. Can anyone advise? Thanks

10-10-2014, 05:05 PM	#2
Rude Dude Registered User Join Date: Sep 2005 Location: Glendale Arizona Posts: 1,188	Re: Brake booster vacuum Intake manifold should have a plug at rear of manifold __________________ http://67-72chevytrucks.com/vboard/s...d.php?t=436442

10-10-2014, 05:10 PM	#3
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum Ah I see, that maybe where I thought the fuel was gonna go in. Holley 4 barrel.

10-10-2014, 06:24 PM	#4
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: Brake booster vacuum There is a port in the intake runner between the carb and dist. You can get the tee fitting at auto store. Big one goes to the vaccum booster, small to auto trans vacuum modulator if there is one. Dist is feed from port in carb. Big fitting at the back of the carb is for PVC valve from valve cover. Attached Images __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

10-11-2014, 10:15 AM	#5
Speedbumpauto Registered User Join Date: Aug 2011 Location: Tucson, AZ Posts: 917	Re: Brake booster vacuum Most Holleys have a 3/8 port at the rear that will serve vac boosters and/or PCV.

10-11-2014, 07:33 PM	#6
la hi Registered User Join Date: Oct 2011 Location: Pagosa Springs, CO Posts: 162	Re: Brake booster vacuum I have a 454 with the thumper cam. the engine will not generate enough vacuum to operate the power brake booster. I mounted the vacuum pump under the cab and the tube from the pump direct to the power brake booster. This pump is electric, noisy, runs a lot, vibrates, and you have to make sure the the electrical connection stays connected.

10-12-2014, 05:06 PM	#7
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum Is that 3/8 BSP?

10-12-2014, 05:10 PM	#8
la hi Registered User Join Date: Oct 2011 Location: Pagosa Springs, CO Posts: 162	Re: Brake booster vacuum I am not sure what you mean?

10-12-2014, 05:15 PM	#9
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum Most Holleys have a 3/8port at the rear that will serve vac boosters and/or PCV.

10-12-2014, 05:15 PM	#10
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,705	Re: Brake booster vacuum There are some belt driven vacuum pumps out there designed to go on Diesels in pickups that would adapt easily. If I was running power steering I'd seriously consider a hydroboost setup and not worry about vacuum. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

10-12-2014, 05:16 PM	#11
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum I'm not running power steering

10-12-2014, 05:38 PM	#12
la hi Registered User Join Date: Oct 2011 Location: Pagosa Springs, CO Posts: 162	Re: Brake booster vacuum Sorry, I did not read it thoroughly. I used the vacuum pump because my Thumper cam, edelbrock carb and the intake manifold would not put out enough vacuum to operate the power brake booster. The only vacuum I need is for the power brakes and the vacuum pump gets the job done. I do believe that the hose is 3/8" as you asked. The power brake unit is also under the cab and it is a short run. I can not see using vacuum for any function going forward or I would install a vacuum reservoir between the pump and the power brake booster.

10-13-2014, 01:12 AM	#13
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: Brake booster vacuum I don't think he is having an issue with low vacuum, just wants to know where the hose goes. Most manifolds, even after market, come with the port I showed. GM sold millions of car using it without any problems. It is where I ran mine under floor booster hose to, works great. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

10-13-2014, 01:19 AM	#14
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum Yeah, I haven't got anything being a project that I've taken over, thanks

10-13-2014, 08:24 AM	#15
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum The carb is too close to the hole to screw a Tee in there. I might have room to screw an elbow, then the Tee



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10-13-2014, 01:06 PM	#17
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum Best picture I have at the moment Attached Images

10-13-2014, 01:46 PM	#18
Old Crow Registered User Join Date: Nov 2012 Location: Fox, AR Posts: 394	Re: Brake booster vacuum Yet another reason to hate Holley carbs. Elbow and a Tee it is. Make sure there isn't an open fitting/threaded hole on the back of the carb base plate. __________________ Old Crow '54 Chevy Panel, '00 Bounder 36S, '95 Jeep YJ

10-13-2014, 03:03 PM	#19
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: Brake booster vacuum Or there is plenty of room to put the carb on a spacer plate, would improve fuel delivery too. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

10-13-2014, 05:18 PM	#20
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum I'm gonna put a 3/8 plug in that hole & connect the booster hose to the outlet at the back of the carb on the spacer. I'm also gonna come off a smaller outlet at the front to go to the gearbox.

10-14-2014, 09:00 AM	#21
Russell Ashley Registered User Join Date: May 2010 Location: Lawrenceville, Ga Posts: 2,648	Re: Brake booster vacuum There's a charcoal filter that goes in the vacuum line to the booster. I've read that you should have one or the gas fumes shorten the life of the booster. They're cheap so not a big expense, and readily available. Here's a link if you are not familiar with what I'm talking about. https://www.google.com/?gws_rd=ssl#q...booster+filter

10-14-2014, 09:10 AM	#22
yoshi Registered User Join Date: Oct 2014 Location: uk Posts: 621	Re: Brake booster vacuum I have seen one fitted to a truck & I wondered what it was. That link isn't working for me

10-14-2014, 11:51 AM	#23
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,705	Re: Brake booster vacuum It's just a thought but I've had to remove the carb to put a T in that spot when I ran Holley carbs on my truck. If you don't have an automatic you wouldn't need a T though and an elbow or straight fitting would work. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

10-14-2014, 01:58 PM	#25
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: Brake booster vacuum Russell Good point, now I need to add it to the to do list.. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

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