Edelbrock tuning question - 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 04-29-2013, 07:13 PM
GTNMUDY's Avatar
Registered User
 
Join Date: Apr 2013
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Edelbrock tuning question

I am trying to tune my 1406 Eldebrock carb. It seems to be stumbling at about 2000 rpm. I can feel it kinda missing slightly. I have replaced the excel pump, fuel pump, floats are ok, Idle just fine. The carb has been sitting for 6 years now and when I first started it it was terrible at any speed. I have disassembled it and cleaned out all jets, fuel passages. This improved the operation but still has a slight stumble at my cruseing speed of 2000.

I have the main metering rod springs and reading the book it stated different colors for different staging vacuums. I am assuming that the staging vacuum means what my manifold pressure is at crusing and under load. At 2000 rpm my vacuum is about 10"hg. With that it would seem I would install the heaviest spring (plain one).

I have done that and it did seem to help but not like it use to be 6 years ago.

My thought was to rejet the main to .100 (it has a .098 now).

Any thoughts from a Edelbrock fan

Oh yeah, it is on a 350 SBC, headers, cam, roller rockers Edlebrock manifold.

Larry
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-29-2013, 08:04 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,182
Wiki Edits: 0

Thanks: 2
Thanked 292 Times in 289 Posts
Most carb problems are actually ignition system problems
This is where you start.
Get a AFR gauge and a manifold vacuum gauge.
You will lean a lot more by working with these two tools than asking questions here.
edelbrock carb tuning.
Volvord 784VC Edelbrock Carburetor

If the motor was good 6 years ago, but now is not good, it is likely a ignition issue.
and or a vacuum leak. Fix these before digging into the carb.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-29-2013, 08:39 PM
GTNMUDY's Avatar
Registered User
 
Join Date: Apr 2013
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
You know I thought the same thing when I started to put the CJ-7 back on the road. I was back firing and just poor running. I checked the header temps and thought I had 2 cyl the were not firing all the time, 100 degrees lower than the other 6. New plugs didnt solve the issue, new Accell, 7mm wires didnt help either. Timing is dead nuts on, replaced the dist cap on the Mallory Unilite dist. Compression was 160 psi on the cyl.

Still back fire, problem was my fuel pump. At idle it was ok but when I jumped on it it ran out of gas in the floats.

After new pump, exel pump and rebuild the carb I now have a driveable Jeep with a slight stumble at 2000 rpm.

When I put this thing to sleep 6 yrs ago it was a beast on the road, 120+ mph was not a issue.

I know it must just be some little issue with the carb. If I cannot get it right I might put the Holley back on. I took the Holley off due to float issues when off roading.

Thanks for your input....

I think if some one know what the STAGGING vaccum is refering to would maybe help me understand what metering spring to use.

Larry

Last edited by GTNMUDY; 04-29-2013 at 08:45 PM.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-29-2013, 09:46 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,247
Wiki Edits: 0

Thanks: 13
Thanked 223 Times in 208 Posts
The metering spring controls when the secondary step of the rods come into play, if you have a bigger than stock cam you likely need a lighter spring. Try cleaning out the air bleed orfices, in my experience they're where edelbrock carbs clog up most often. They need to be spotless.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-30-2013, 08:40 AM
GTNMUDY's Avatar
Registered User
 
Join Date: Apr 2013
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I'm going to call Edelbrock tech support and see what they say.

I'll post there comments..

Larry
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-30-2013, 12:08 PM
GTNMUDY's Avatar
Registered User
 
Join Date: Apr 2013
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Called tech support. Explained my problems. Asked him what the staging vacuum was refering to. Was told my manifold pressure at IDLE.

Since I was at 16 inches of vacuum I was told to put the strongest spring in (already done that).

Next advised me to use the TOP hole on the Excel pump lever. Book states center hole is to be used with the 1406 carb. This should give more fuel when advancing the accelerator.

Well, the fix took about 30 sec. took it on a test run and it did improve the mid range.

Sometime the littlest things can be over looked

thanks for your help.

Larry
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
Edelbrock tuning help Beachernaut Engine 17 07-09-2010 09:46 AM
Question on tuning edelbrock performer carb eric32 Engine 1 09-05-2009 09:12 PM
edelbrock tuning question Sasquatch Engine 6 05-26-2008 09:27 PM
tuning edelbrock carbs 1969cutlass Engine 2 07-31-2002 02:20 PM
Edelbrock carb tuning Oldsmoblily Engine 4 06-12-2002 06:44 PM


All times are GMT -6. The time now is 07:27 PM.


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.