holley carb tuning - 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
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 05-30-2010, 07:22 PM
Registered User
Join Date: Dec 2007
Location: Toronto
Posts: 34
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
holley carb tuning

Hi all,

I run a chevy 355ci all old school in an 85 transam with stock th700r4 tranny and stock converter. I'm getting now 25l/100kms in city driving being very gentle. I wanna try to tune the holley 750 4160 vacuum secondaries I have on this engine to get a better gas mileage so here is what I was thinking to do if you could tell me if that would help or be worse etc...:

-Move the distributor vacuum advance from ported to manifold vacuum ( should I then back the distributor to avoid to much advance??
-Put a spring in the vacuum secondaries housing that opens at the highest rpm ( maybe the black spring)
-Put a wire in the IFR (Idle feed restrictors)to limit the opening.
-Leave the 67 actual main jets.
-Tune then the carb with a vacuum gauge to get the highest RPM.

Thanks guys!

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 05-30-2010, 07:30 PM
Registered User
Join Date: Dec 2004
Location: San Jose Ca
Age: 65
Posts: 472
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Do not retard the timing when hooking up the vacuum advance,at wot there is little vacuum so the advance is not working,but under cruise it will advance the timing to help backing out of the throttle. Is the dist set up for advance curve,how much timing are you running ,what engine specs,what cam, what gears,more info
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-30-2010, 07:59 PM
Registered User
Join Date: Dec 2007
Location: Toronto
Posts: 34
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Don't have a clue about the advance I have ( not the stock damper as the damper from the LG4 has been put back on this 350..( got the car this way), gear is 3.08 and tranny is stock th700r4 with stock converter as well.
Engine is forged internal, sportsman 2 heads, comp cam XE284, dual plane intake world, holley 750, hedders , free flow exaust etc..
car works flawlessly jut burns to much in city.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-30-2010, 09:40 PM
solidaxel's Avatar

Last journal entry: Project garage complete!
Last photo:
Join Date: Jul 2003
Location: So. Arizona
Posts: 558
Wiki Edits: 0

Thanks: 2
Thanked 1 Time in 1 Post
NO problem that combo. is just right, I do see a problem with your right foot thou!!

There is a VERY fine line between performance and gas mileage.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-30-2010, 11:01 PM
cobalt327's Avatar
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Posts: 5,031
Wiki Edits: 1616

Thanks: 128
Thanked 616 Times in 565 Posts
The brown or black secondary spring will all but prevent the secondaries from opening, so if this will help matters, use one of them. Or just go easier on the throttle.

Using manifold vacuum will not increase the total advance while under heavy load/throttle. If the timing is correct now and you change from ported to manifold, all you will do is lower the idle speed to compensate for the increase in idle speed this causes.

If you hear pinging on throttle tip-in, you will need to physically limit the vac can's travel w/a vacuum advance limiter plate: Crane #99619-1, instructions for installing and setting it: #99619-1.
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:
Please select your insurance company (Optional)


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 tuning help needed biscuitville Engine 23 08-04-2008 07:49 PM
Holley Carb. Question crusherdbuzz Engine 2 07-02-2006 03:25 PM
Holley Carb Tuning Question Frankoholic78 Engine 1 05-23-2006 08:38 PM
Holley Tuning on a 230 Chevy sicksixseven Engine 8 05-04-2006 08:58 PM
Holley carb tuning help! frankenvette Engine 3 08-12-2004 09:35 PM

All times are GMT -6. The time now is 08:52 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.