Carb issues - 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 04-07-2013, 02:31 AM
Nemeth's Avatar
My 327 Cruiser
 
Join Date: Nov 2012
Location: Riverside California
Age: 46
Posts: 25
Wiki Edits: 0

Thanks: 4
Thanked 1 Time in 1 Post
Carb issues

Hey guys I got a 670 Avenger vac secondaries that i cannot get the secondary hesitation out. 383 sbc 180 cc heads,236/242 @ .050 duration 2500 stall 700r4, 373 gears. Maybe a 750 mechanical ???

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-07-2013, 07:58 AM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 7,405
Wiki Edits: 0

Thanks: 291
Thanked 707 Times in 682 Posts
you can fix the 67o. I use 750 or bigger on any sbc,but you have the 670.
Is the hesitation only when you sneak up on the secondaries or any time you floor it?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-07-2013, 10:04 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Quote:
Originally Posted by Nemeth View Post
Hey guys I got a 670 Avenger vac secondaries that i cannot get the secondary hesitation out. 383 sbc 180 cc heads,236/242 @ .050 duration 2500 stall 700r4, 373 gears. Maybe a 750 mechanical ???
Often, secondary hesitation is caused by a too-quick opening rate. When that happens (too quick sec. opening) there's a lean "hole" in the air/fuel delivery. The way to counter this is to either slow the secondary opening rate (usually works best), or try to extend the accelerator pump shot to cover the lean hole.

There are several ways to tailor the secondary opening rate of a vacuum secondary Holley, but the first thing I recommend is to use the next stiffer secondary diaphragm spring and note the results.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-08-2013, 05:08 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Also check to be sure the secondary housing has the check ball in place, and that the check ball isn't sticking.

Click on image for more info:

Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-08-2013, 10:53 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,547
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
There is a small groove under the check ball too. Sometimes that groove,( taht allows some air to sneek around the check ball and all vacuum to build in the vac housing,,,need enhancement ... make sure the vac housing to body gasket is good.

Primary and sec idle throttle position must be correct at idle ( T slot exposure) or the secondaries will bog.

The cam you have will require a good bit of idle spark advance to ensure correct Tslot exposure at idle.

These SA series carb tend to be kind of lame , out of the box.
Needs lots of upgradeing and tuning.

start with the timing curve and idle timing.
idle 24-26deg
10-12deg advance curve
34-36deg at max advance.

10-12deg of max vacuum advance, using ported vacuum.
corrected pri and sec idle T slot exposure.

.031" shooter.

jetting may need work.

a 750 carb ALLWAYS WORKS BETTER.. Do not buy another SA carb. Get a real holley 750.
Or build your own using a 650+cfm DP holley donor + the holley proform HP 750 body kit.

You could us a better torque converter. 3000++stall for that cam.
3500 is best. The 2500 stall is tame. a factor.
Getting the timing right will help a lot.

Last edited by F-BIRD'88; 04-08-2013 at 10:58 AM.
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
Carb Issues NovaJoe1973 Engine 13 12-27-2011 07:12 AM
Carb issues mgregory96 Engine 4 10-11-2011 06:19 AM
Carb issues... petes67bird Engine 7 09-30-2011 09:58 PM
carb issues mjascur Engine 7 06-06-2010 04:52 PM
carb issues I think mjascur Engine 1 06-05-2010 08:17 PM


All times are GMT -6. The time now is 10:32 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.