vacuum advance trouble - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 11-25-2011, 06:10 PM
Registered User
 
Join Date: Nov 2011
Location: boise,id
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
vacuum advance trouble

purchased an 86 chevy w/ a 305. has an edelbrock performer intake and 600cfm carb. has an msd ignition box and dist.cap and rotor. changed carb to a quad jet and have timing as close as possible by ear and eng performance. unable to find a timing marker ANYWHERE. removed most vacuum lines needed for emissions. have big line from carb leading to pcv on valve cover. other carb vac line plugged. need ideas for installing my vacuum advance to a vac line that will increase vac w/ increase in acelleration. tried to use small line on carb but it put dist. in advance all the time. thinking of drilling a hole in bottom of aircleaner and running vac advance to it.... any thoughts, suggestions and help is appreciated.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-25-2011, 06:33 PM
Registered User
 
Join Date: Sep 2011
Location: east of branson mo
Posts: 10
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
vacumn advance

Hi my name is Nial the air cleaner wont supply any vacumn at all. You have two types of vacumn you can use . manifold vacumn, it will decrease the harder you step on the throttle and be highest when off the throttle. This is best for gas mileage.
Port vacumn, It will increase when you got on the throttle.
Manifold vacumn you feel with your finger on the end of the hose. Port vacumn is hard to feel. You will feel it as the engine is accelerating.
Have a good day Nial
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-26-2011, 05:33 PM
Registered User
 
Join Date: Nov 2011
Location: boise,id
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
vac adv.

the only vacuum i have is on the carb and i ran that to the pcv. there is another vac port on carb but when i use that for vac adv it runs high all the time. so i need a port that has minimal vac while idle and increases w/ acceleration. have a few vac ports on manifold but they have no vac at all. ever. they are not working. unless it is such a small amount i cant feel it, but seems unlikely. will try it anyway.

thanx
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-26-2011, 06:09 PM
carsavvycook's Avatar
My 2 cents worth
 
Last photo:
Join Date: Sep 2007
Location: Lakeside, CA
Age: 57
Posts: 2,855
Wiki Edits: 3

Thanks: 2
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by 305rocker
the only vacuum i have is on the carb and i ran that to the pcv. there is another vac port on carb but when i use that for vac adv it runs high all the time. so i need a port that has minimal vac while idle and increases w/ acceleration. have a few vac ports on manifold but they have no vac at all. ever. they are not working. unless it is such a small amount i cant feel it, but seems unlikely. will try it anyway.

thanx
Use the manifold vacuum port, and re-adjust your base idle speed to your final speed you are comfortable with.

Your base timing is set with it disconnected, and plugged. This may be somewheres between 0, and 12 degrees initial timing.

The amount of advance with it hooked up, will make a huge difference in fuel mileage saving, and performance.

This in turn can cause engine failure, if any detonation/pinging is heard.

PM me with any question's.

Stephen
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-26-2011, 07:03 PM
Custom10's Avatar
my KARMA ran over my DOGMA
 

Last journal entry: SS
Last photo:
Join Date: May 2009
Location: Saskatchewan, Canada
Age: 49
Posts: 1,069
Wiki Edits: 0

Thanks: 10
Thanked 21 Times in 19 Posts
rocker u would be best advised to first find tdc and verify your timing marker with the dampener circumference. search wiki for finding TDC and Making a timing tape, do this and get a timing light and a vacuum gage, then tuning the thing will give results.

The only piece hooked up to the air cleaner should be the air breather on the valve cover opposite the PCV valve, dist vacuum is not sourced at the air cleaner.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-26-2011, 07:30 PM
Registered User
 
Last photo:
Join Date: Jun 2011
Location: USA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by nialkc
Hi my name is Nial the air cleaner wont supply any vacumn at all. You have two types of vacumn you can use . manifold vacumn, it will decrease the harder you step on the throttle and be highest when off the throttle. This is best for gas mileage.
Port vacumn, It will increase when you got on the throttle.
Manifold vacumn you feel with your finger on the end of the hose. Port vacumn is hard to feel. You will feel it as the engine is accelerating.
Have a good day Nial
The ported vacuum will also drop off when you step on the throttle harder.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-26-2011, 07:52 PM
streetbruiser's Avatar
Registered User
 
Join Date: Nov 2011
Location: Illinois
Posts: 76
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
If you are running a quadrajet there is almost always a small vacuum port above the baseplate on front right side of carb for distributor advance. As advised you gotta start with getting it timed properly. You are probably way off if you are timing by ear, Thats like building a house without a level. No vacuum at intake manifold port... WTF?? That sounds impossible to me. I bet your timing is way advanced.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-26-2011, 11:34 PM
Registered User
 
Join Date: Nov 2011
Location: boise,id
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
not sure if timing is exact, but it runs pretty damn well now. i found tdc and installed dist. had to adv it completely to run. removed dist and found tdc again. turnd the screw under dist 180* and now its close. has good idle, accel and power. put when peddle is fully pressed it stalls. the edelbrock intake manifold has a plugged hole behind carb. and a vac port on top of AND next to therm housing. no vac there. either place. i imagine if ALL vac lines where connected they would work, but most were cut and removed before i bought the truck. wonder if the plugged port would work.... the small vac line on right side of carb put the idle very high ALL the time. does that mean i am advanced too much and it has too much vac?
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-26-2011, 11:38 PM
Registered User
 
Join Date: Nov 2011
Location: boise,id
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
vac adv.

i will take a few photos of what i have and describe each and my process as well. this will be done tomorrow afternoon or so. mountain time. thanks to all thoughts and ideas, much appreciated.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-27-2011, 07:14 AM
Member
 
Last photo:
Join Date: Dec 2004
Location: San Antonio, Texas
Age: 50
Posts: 4,021
Wiki Edits: 0

Thanks: 0
Thanked 23 Times in 23 Posts
here is a nice timing writeup.

has some good timing numbers to use at the end of the article.

http://www.corvette-restoration.com/.../Timing101.pdf
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Opinions on ported of full vacuum for vacuum advance ? y2k600f4 Engine 15 10-07-2011 09:38 PM
vacuum advance rwa1015 Engine 12 05-01-2011 10:03 AM
Timing... vacuum or no vacuum advance? 454ChevelleMalibu Engine 18 04-25-2010 09:37 PM
ok to use same vacuum line for vacuum advance and tranny vacuum modulator? brian400ex Engine 4 02-19-2003 02:25 PM
computer advance or vacuum advance?? 1984camaroZ28 Engine 1 10-12-2002 02:57 PM


All times are GMT -6. The time now is 04:35 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.