Vacuum gauge - Pontiac GTO Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 7 (permalink) Old 08-12-2012, 01:26 PM Thread Starter
 
gtoearl's Avatar
 
Join Date: Dec 2009
Location: ROSEVILLE, CA
Posts: 192
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Vacuum gauge

I purchased a used vacuum gauge for my 66 gto. I hooked it up directly into the intake manifold. It works but it doesn't get in to the green, no matter what rpm. At idle in park it's in the yellow..........Any suggestions.......
gtoearl is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 08-12-2012, 02:29 PM
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 8,491
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 102 Post(s)
Connect another vacuum gauge to the intake and verify that your old gauge is accurate. If so, and you have low manifold vacuum, it could be due to retarded timing, camshaft design, or other issues.
geeteeohguy is online now  
post #3 of 7 (permalink) Old 08-12-2012, 06:42 PM Thread Starter
 
gtoearl's Avatar
 
Join Date: Dec 2009
Location: ROSEVILLE, CA
Posts: 192
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
thnaks for the reply.......going to put a tri power on in the near future..........just thought that maybe I had it hooked up wrong........I do have a mild cam with a little higher lift. Not sure just how much......
gtoearl is offline  
 
post #4 of 7 (permalink) Old 08-13-2012, 11:46 AM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,737
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
Could be the cam. Lift generally alone won't affect vacuum much, but increased duration will, especially if it results in more overlap. (Period where both intake and exhaust are open). Does your new vacuum gauge also have a numeric scale on it, or is it just marked with color bands?

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
post #5 of 7 (permalink) Old 08-13-2012, 01:58 PM Thread Starter
 
gtoearl's Avatar
 
Join Date: Dec 2009
Location: ROSEVILLE, CA
Posts: 192
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Here's a pic of the vac gauge I have.........The gauge never reads better than about 10. But mostly during driving conditions it's 8 or less....When I step on the gas a ltttle hard it pins to right............thanks for your help........

On another note bearGFR, I noticed in your pics that you installed roller rockers..........I'm thinking of the same for my 389 bored out to 400 with # 16 1968 heads..........I've already got a tri power coming for it..........What manufacture or type would you recommend? I'm also thinking of just roller tip rockers as I'm not concerned about more horses.........just to have adjustment to valves is my conceern.........


By the way.............DOES ANYBODY KNOW THIS NAME..........Mike Wasson in Brimfield, IL http://www.pontiactripower.com/index.html

He's building a tri power for me.........
Attached Thumbnails
Click image for larger version

Name:	$T2eC16hHJHQE9nzEzuD5BQGsyb2ct!~~60_57[1].jpg
Views:	215
Size:	403.8 KB
ID:	15449  

Last edited by gtoearl; 08-13-2012 at 02:51 PM.
gtoearl is offline  
post #6 of 7 (permalink) Old 08-13-2012, 06:14 PM
 
Join Date: Mar 2011
Location: Texas
Posts: 704
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
or bad gauge. they can be zeroed internally.
pontiac is offline  
post #7 of 7 (permalink) Old 08-13-2012, 10:18 PM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,737
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
Unless you've got a -really- rowdy cam, 10 is very low. I'm running a moderate solid roller in mine and it makes around 11 or 12 at idle once it's warm. I'd suspect the gauge. You can get a relatively inexpensive one at most big box parts stores that would allow you to compare readings. Where do you have your current gauge connect for a vacuum source?

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO General Discussion

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Gauge trim panelwith round gauge in corners, cpr Interior Discussions 1 05-19-2011 04:14 PM
Vacuum Gauge Install gtoearl 1964-1974 Tempest, Lemans & GTO General Discussion 20 06-13-2010 08:00 AM
67 GTO vacuum gauge Eric Animal 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 5 05-09-2008 08:45 PM
fuel pressure gauge & boost gauge sdgoat Service, Maintenance and Technical Discussion 4 05-12-2006 09:34 AM
GTO Vacuum gauge wanted Goatflyer73 1964-1974 Tempest, Lemans & GTO General Discussion 2 10-18-2005 06:00 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome