Hard to idle with the A/C on - 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 07-02-2012, 11:00 AM
Registered User
 
Last photo:
Join Date: Jul 2009
Location: San Antonio
Posts: 95
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hard to idle with the A/C on

Guys,

I'm having trouble getting my 69 mustang to idle when I put the A/C on. I have a 302 with a moderate sized solid roller cam and 4 spd. i live in Texas so a few yrs ago I put a vintage air system in. It idles fine at around 1,000-1,100 until I put the A/C on and then the idle drops way down to 400-500 and I need to tap the gas to keep it running. In order to get it to idle ok with the A/C on I have to turn the idle up to 1,500 with the A/C off. It is especially a pain when I stop for red lights/stop signs as the car wants to stall. Other than that the car runs fine. Any thoughts?

Mike

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-03-2012, 05:08 PM
Registered User
 
Last photo:
Join Date: Apr 2012
Posts: 145
Wiki Edits: 0

Thanks: 1
Thanked 12 Times in 12 Posts
You could simply put in a solonoid that kicks up the idle (pushes on the carb linkage) when you turn on the A/C. This was a typical arrangement for many stock engines and carb brackets and solonoids are common. The A/C unit may even have a "switch" that comes on with the compressor just for this purpose.

Actually, isn't this the beastie from a Ford Mustang of your year with your engine?


http://www.ebay.com/itm/New-67-68-69...sories&vxp=mtr

Last edited by toddalin; 07-03-2012 at 05:14 PM.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-03-2012, 05:33 PM
Registered User
 
Last photo:
Join Date: Jul 2009
Location: San Antonio
Posts: 95
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the feedback. Actually, I have a Mallory Unilite distributor with mechanical advance, and the distributor is already set up exactly as you suggest: 26 initial with 36 total, all in at around 3000ish. I rebuilt the 750 carb and was able to eliminate all the problems I posted about previously. Now the car runs well, except when the air is on. I think I will look into putting in the A/C solenoid you suggest. I was not aware that even factory cars came with those. It makes sense and I think it will take care of the problem.

Mike
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-04-2012, 01:06 PM
Registered User
 
Last photo:
Join Date: Jul 2009
Location: San Antonio
Posts: 95
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I'm not sure, but I understood that with the way my dist is set up the timing can never be less than 26 total timing. this dist has an adjustable advance timing limit. Currently it is set to give only 10 degrees advance. then I set the wieghts and springs so that the timing mark moves through that ten degrees when I rev the enginge, with full advance at around 3000. Then I power timed the car to 36 degrees. so AFAIK the most the timing can retard to from the peak is to 26 degrees, even if the idle drops down to zero the timing can never be less than 26 degrees, correct?

Thanks for the info on the solenoids. I will be sure to pick up the right one. I think that will fix the whole problem.

Mike
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:
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
82 corvette hard to start,won't idle cold & lousy mileage evanst Modern Electronic Engines 13 04-07-2012 12:43 PM
Rough idle, high idle in park, stalls in gear.. Help! ratmaro Engine 16 03-23-2012 06:29 PM
355 twin turbo hard time getting motor to idle good Project89 Engine 9 12-01-2011 08:01 PM
Hitting Hard When Shifting into Drive at Idle My68Vette Transmission - Rearend 10 09-06-2009 07:14 PM
BG/BC Rich Idle & Idle Air Bleeds/IFR 68NovaSS Engine 3 11-11-2006 12:36 AM


All times are GMT -6. The time now is 04:24 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.