Vacuum Booster question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kgmunro · 08-29-2012, 07:47 AM

I am installing power brakes on my 65 gmc and was wondering where to tap vacuum for the booster. The truck has a 230 6 cyl right now with a single barrel carb.

kgmunro · 08-30-2012, 07:10 AM

does anyone know where I can draw vacuum??

**yelmer** · 08-30-2012, 08:37 AM

intake manifold near carb

tincan1966 · 08-30-2012, 08:38 AM

Check your intake manifold, to the rear of the carb, I believe some have a plug in the runner there that can be removed. Install a 1/4" NPT fitting with a 3/8" barb on the other end, and run hose to booster. Another option, is to "T" into the PCV hose.

kgmunro · 08-30-2012, 09:07 AM

thanks guys I wasn't too sure...

**jocko** · 08-30-2012, 08:07 PM

to be safe - make sure you stick a vac gauge on it to know if it's full time vac. Some of the smaller ports on the carb are not full-time. If you have 16+" Hg at idle, you're good to go. Accidentally hooking to a part time vac signal would defeat your power braking upgrade. As mentioned above, the full time ports are usually located low - sometimes pointing out the back, sometimes pointing out the front - carb dependent.

kgmunro · 08-30-2012, 09:04 PM

Right-on, thanks jocko!

08-29-2012, 07:47 AM	#1
kgmunro Registered User Join Date: May 2009 Location: Brandon Manitoba Canada Posts: 342	Vacuum Booster question I am installing power brakes on my 65 gmc and was wondering where to tap vacuum for the booster. The truck has a 230 6 cyl right now with a single barrel carb.

08-30-2012, 07:10 AM	#2
kgmunro Registered User Join Date: May 2009 Location: Brandon Manitoba Canada Posts: 342	Re: Vacuum Booster question does anyone know where I can draw vacuum??

08-30-2012, 08:37 AM	#3
yelmer Registered User Join Date: Aug 2008 Location: greeley colorado Posts: 1,360	Re: Vacuum Booster question intake manifold near carb

08-30-2012, 08:38 AM	#4
tincan1966 Registered User Join Date: Oct 2010 Location: Independence,KS Posts: 1,477	Re: Vacuum Booster question Check your intake manifold, to the rear of the carb, I believe some have a plug in the runner there that can be removed. Install a 1/4" NPT fitting with a 3/8" barb on the other end, and run hose to booster. Another option, is to "T" into the PCV hose.

08-30-2012, 09:07 AM	#5
kgmunro Registered User Join Date: May 2009 Location: Brandon Manitoba Canada Posts: 342	Re: Vacuum Booster question thanks guys I wasn't too sure...

08-30-2012, 08:07 PM	#6
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,976	Re: Vacuum Booster question to be safe - make sure you stick a vac gauge on it to know if it's full time vac. Some of the smaller ports on the carb are not full-time. If you have 16+" Hg at idle, you're good to go. Accidentally hooking to a part time vac signal would defeat your power braking upgrade. As mentioned above, the full time ports are usually located low - sometimes pointing out the back, sometimes pointing out the front - carb dependent.

08-30-2012, 09:04 PM	#7
kgmunro Registered User Join Date: May 2009 Location: Brandon Manitoba Canada Posts: 342	Re: Vacuum Booster question Right-on, thanks jocko!



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