Vacuum gauge woes... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**HIGHWAY BY THE SEA** · 06-24-2014, 03:56 PM

I am trying to attach a stock vacuum gauge to my inline 6 on my 68 C10. I have seen pictures on here, but they confuse me since some hose ends are not shown. Can someone clear this up with pictures that show where EVERY hose and attachment go?

davepl · 06-24-2014, 04:05 PM

You'll never get it perfect because so far as I know a C10 couldn't have a vacuum gauge. You needed to be in the medium duty (C40+) to get them, I think.

So, even if we can document it someone will have to chime in as to whether the C40+ firewall holes are the same as C10-C30.

I haven't connected mine yet either. If I wind up with a spare firewall hole or room in an existing grommet I'll do that, otherwise likely T off the line coming in for HVAC under the dash.

Page 191 of the assembly manual shows the engine vacuum line config for the L6.

**Already Gone** · 06-24-2014, 04:49 PM

If your truck is an automatic then there should be a vacuum fitting on your engine somewhere with a line going to the trans for the modulator. I'd use that port for your vacuum line but you will probably have to get a double tree vacuum fitting for the engine. In the firewall notch and just towards the drivers side of the truck there is a rubber grommet in the firewall that some wires and your oil pressure gauge line go through and then to your gauge pod . I'd use that grommet to run the line from your vacuum source to the gauge. Hope this info helps and unfortunatly I do not have any pictures..

**HIGHWAY BY THE SEA** · 06-24-2014, 06:32 PM

Mine is manual transmission (for now). I thought all I had to do was "T" into the hose that connects to the top of the valve cover and goes to the "nozzle" on the space between the carb and valve area. But the pictures I have seen do not appear to depict that as the correct way. I just got my TEMP and BATTERY gauges working today, and I hope to have the OIL and VAC ones done by tomorrow.

**Already Gone** · 06-24-2014, 06:46 PM

Quote:

Originally Posted by HIGHWAY BY THE SEA

Mine is manual transmission (for now). I thought all I had to do was "T" into the hose that connects to the top of the valve cover and goes to the "nozzle" on the space between the carb and valve area. But the pictures I have seen do not appear to depict that as the correct way. I just got my TEMP and BATTERY gauges working today, and I hope to have the OIL and VAC ones done by tomorrow.

Sorry not at all familiar with the 6 cyl engines.

**HIGHWAY BY THE SEA** · 06-25-2014, 11:53 AM

Anyone...? Anyone...? I wanted to get this done today.

67chevemall · 06-26-2014, 10:51 AM

Ran mine from the bottom feeder on the carb down the engine through the firewall gromet with the oil pressure line/ dist ign wire, ect.. right to the gauge.

Works great.

**HIGHWAY BY THE SEA** · 06-26-2014, 12:21 PM

I ended up attaching the tubing to a small metal nozzle that is on the very bottom of the carb that was plugged with a rubber cap. I hope this is what you mean! The gauge does work with this, however it goes down on rev and up on idle. Is this working right? This is my first experience with a VAC gauge.

**Already Gone** · 06-26-2014, 03:52 PM

Down on rev and up on idle is right. The more vacuum you have the less gas you use.

06-24-2014, 03:56 PM	#1
HIGHWAY BY THE SEA Senior Member Join Date: Nov 2012 Location: BY THE CAROLINA SEA Posts: 922	Vacuum gauge woes... I am trying to attach a stock vacuum gauge to my inline 6 on my 68 C10. I have seen pictures on here, but they confuse me since some hose ends are not shown. Can someone clear this up with pictures that show where EVERY hose and attachment go? __________________ FRANKENTRUCK 1981 Chevrolet C10 Shortbed Stepside GRANDTRUCK 1968 Chevrolet C10 Stepside Longbed http://67-72chevytrucks.com/vboard/s...d.php?t=584617 PROJECT JIGSAW 1967 GMC C3500 GREAT WHITE 1986 Blazer M1009 454 engine w/700R4 transmission gas conversion

06-24-2014, 04:05 PM	#2
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: Vacuum gauge woes... You'll never get it perfect because so far as I know a C10 couldn't have a vacuum gauge. You needed to be in the medium duty (C40+) to get them, I think. So, even if we can document it someone will have to chime in as to whether the C40+ firewall holes are the same as C10-C30. I haven't connected mine yet either. If I wind up with a spare firewall hole or room in an existing grommet I'll do that, otherwise likely T off the line coming in for HVAC under the dash. Page 191 of the assembly manual shows the engine vacuum line config for the L6. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

06-24-2014, 04:49 PM	#3
Already Gone 70+ ( Old Skool Club ) Join Date: Nov 2003 Location: Saskatoon, Saskatchewan ,Canada Posts: 9,143	Re: Vacuum gauge woes... If your truck is an automatic then there should be a vacuum fitting on your engine somewhere with a line going to the trans for the modulator. I'd use that port for your vacuum line but you will probably have to get a double tree vacuum fitting for the engine. In the firewall notch and just towards the drivers side of the truck there is a rubber grommet in the firewall that some wires and your oil pressure gauge line go through and then to your gauge pod . I'd use that grommet to run the line from your vacuum source to the gauge. Hope this info helps and unfortunatly I do not have any pictures.. __________________ 1972 C10 Custom/Deluxe 613 Highlander 406/700R4 1999 White Tahoe LS 4x2 with Z56 Police Package 1992 K1500 GMC Suburban Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601 " Circumsatances Do Not Change Responsibility " " The Sky is not the Limit, Your Mind is." Marilyn Monroe .. RIP Charlie Watts 1941 - 2021

06-24-2014, 06:32 PM	#4
HIGHWAY BY THE SEA Senior Member Join Date: Nov 2012 Location: BY THE CAROLINA SEA Posts: 922	Re: Vacuum gauge woes... Mine is manual transmission (for now). I thought all I had to do was "T" into the hose that connects to the top of the valve cover and goes to the "nozzle" on the space between the carb and valve area. But the pictures I have seen do not appear to depict that as the correct way. I just got my TEMP and BATTERY gauges working today, and I hope to have the OIL and VAC ones done by tomorrow. __________________ FRANKENTRUCK 1981 Chevrolet C10 Shortbed Stepside GRANDTRUCK 1968 Chevrolet C10 Stepside Longbed http://67-72chevytrucks.com/vboard/s...d.php?t=584617 PROJECT JIGSAW 1967 GMC C3500 GREAT WHITE 1986 Blazer M1009 454 engine w/700R4 transmission gas conversion

06-25-2014, 11:53 AM	#6
HIGHWAY BY THE SEA Senior Member Join Date: Nov 2012 Location: BY THE CAROLINA SEA Posts: 922	Re: Vacuum gauge woes... Anyone...? Anyone...? I wanted to get this done today. __________________ FRANKENTRUCK 1981 Chevrolet C10 Shortbed Stepside GRANDTRUCK 1968 Chevrolet C10 Stepside Longbed http://67-72chevytrucks.com/vboard/s...d.php?t=584617 PROJECT JIGSAW 1967 GMC C3500 GREAT WHITE 1986 Blazer M1009 454 engine w/700R4 transmission gas conversion

06-26-2014, 10:51 AM	#7
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	Re: Vacuum gauge woes... Ran mine from the bottom feeder on the carb down the engine through the firewall gromet with the oil pressure line/ dist ign wire, ect.. right to the gauge. Works great. __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

06-26-2014, 12:21 PM	#8
HIGHWAY BY THE SEA Senior Member Join Date: Nov 2012 Location: BY THE CAROLINA SEA Posts: 922	Re: Vacuum gauge woes... I ended up attaching the tubing to a small metal nozzle that is on the very bottom of the carb that was plugged with a rubber cap. I hope this is what you mean! The gauge does work with this, however it goes down on rev and up on idle. Is this working right? This is my first experience with a VAC gauge. __________________ FRANKENTRUCK 1981 Chevrolet C10 Shortbed Stepside GRANDTRUCK 1968 Chevrolet C10 Stepside Longbed http://67-72chevytrucks.com/vboard/s...d.php?t=584617 PROJECT JIGSAW 1967 GMC C3500 GREAT WHITE 1986 Blazer M1009 454 engine w/700R4 transmission gas conversion

06-26-2014, 03:52 PM	#9
Already Gone 70+ ( Old Skool Club ) Join Date: Nov 2003 Location: Saskatoon, Saskatchewan ,Canada Posts: 9,143	Re: Vacuum gauge woes... Down on rev and up on idle is right. The more vacuum you have the less gas you use. __________________ 1972 C10 Custom/Deluxe 613 Highlander 406/700R4 1999 White Tahoe LS 4x2 with Z56 Police Package 1992 K1500 GMC Suburban Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601 " Circumsatances Do Not Change Responsibility " " The Sky is not the Limit, Your Mind is." Marilyn Monroe .. RIP Charlie Watts 1941 - 2021



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