Transition circuit on Holley 4160 too lean. - Hot Rod Forum : Hotrodders Bulletin Board -- 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
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 02-17-2013, 08:57 AM
Registered User
Last photo:
Join Date: Dec 2012
Posts: 9
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
Transition circuit on Holley 4160 too lean.

Hi All,
I recently upgraded to 2.5 in exhaust pipe size on my chevy 350 and found that it leaned the A/F ratio. My carb is the 80457-2 it does not have adjustable Idle air bleeds or Idle feed restrictors. Here are my current numbers with a wideband mounted to the drivers header.

Idle - 13.5:1
Off idle to 2.5k - 14.7-17.5 There is no popping or anything, just that I see it go lean.
2.5k+ -13.5:1
WOT - 12.7-13.1

I am okay with 13.5 i think. My worry is in the off idle at low speeds, say 40-50 mph, depending on the load it will go way lean until I get to the main jets around 2500 rpms.

Is my best option to buy an adjustable metering block and if so, what are you guys using?
I saw this one from QuickFuel 34-8. Looks like it has adjustable IFR and powervalve restrictors too. Anybody use one of these?

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 02-17-2013, 01:11 PM
F-BIRD'88's Avatar
Yada Yada Yada
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,284
Wiki Edits: 0

Thanks: 5
Thanked 399 Times in 393 Posts
Check the idle position of the throttles at idle. If the idle position is too far open,, then when you adjust the idle fuel mix screws, the off idle transition will be too lean.
The most common cause of the throttle being too far open at idle is a lack of idle spark advance.
( especially on a cammed motor)

Remove the carb and flip it over and look at both the pri and sec throttle position.
reset as required. .020" T slot exposed at idle on both. even.
The power valve must be closed when idleing in gear.

What cam?... timing at idle?

First look for and correct any exhaust system leaks as this will throw off the AFR gauge.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:


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
Holley Model 4160 zfuel Engine 24 01-29-2012 09:44 AM
Holley 4160 carb dedwards Engine 2 07-15-2011 05:55 PM
help with holley 4160 sam_bo3 Engine 2 03-11-2009 07:10 AM
Holley idle circuit baddbob Engine 2 08-19-2007 08:43 AM
Powdercoating a Holley 4160 rick458 Engine 6 03-21-2005 02:26 PM

All times are GMT -6. The time now is 05:11 AM.

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