Holley Idle mixture screw help - 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 01-27-2009, 04:04 PM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 42
Posts: 220
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
Holley Idle mixture screw help

I have a Holley 600 on my mild 400 smallblock chevy. I'm also running a descent size cam and that is making the tuning difficult. I couldn't get the idle mixture screws to adjust and I figured out the transfer slots were exposed. I opened the rear secondaries a little and some adjustability has come back. However it is in only one idle mixture screw. If you srew one side in all the way the engine will die. When you screw the other side in it will keep running. I just rebuilt this carb and blew out all of the passages. Would opening the secondaries anymore help? What about drilling the front throttle plates?
Thanks for your time and help.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 01-27-2009, 04:12 PM
dawg's Avatar
NAVY VETERAN
 
Last photo:
Join Date: Aug 2004
Location: Colebrook Connecticut
Age: 56
Posts: 920
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 5 Posts
a 600 cfm on a 400 is quite small on a oem 400 and one with a cam is really too small.
I seen this problem before and its caused by using the wrong metering block to carb body gasket.
your blocking a hole that should be open.
my guess is on the side that has no change.
get the right gasket for your carb and it should fix it.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 01-27-2009, 07:03 PM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: z'ville,oh.
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
holley

Was it working before? Try removing the idle screw and spray carb. cleaner in it and blow it out alittle w/ lower pressure air. Or the air bleeds down in the air hone may be dirty also. Just a suggestion..
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 01-28-2009, 12:05 AM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 42
Posts: 220
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
It has a Comp Cams XE284.
Thanks again
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 01-28-2009, 07:30 AM
Member
 
Last photo:
Join Date: Dec 2004
Location: San Antonio, Texas
Age: 51
Posts: 4,023
Wiki Edits: 0

Thanks: 0
Thanked 24 Times in 24 Posts
yes, more timing will help a lot.

I would run as much initial timing as you can (right before the starter starts to complain when turning over a hot engine) then use the vacuum advance on the manifold source. should be between 16 and 20 degrees initial then another 10 to 14 from the vacuum advance. So and idle timing in the mid 30's will make the idle rpm increase a lot which will allow the idle screws to be should down so the blades are in the slot.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 01-29-2009, 01:47 AM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 42
Posts: 220
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
Thanks for the replies. I will bump up my initial timing and see if that helps. I did replace my 6.5 powervalve with a 5.5. I guess I should have went lower. In the past I have had hot restart problems with this engine. it doesn't seem to like alot of initial timing. However my 11-1 CR doesn't help.
Thanks again guys for your help.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 01-29-2009, 09:10 AM
Technical Support Barry Grant
 
Last photo:
Join Date: Jul 2003
Location: Dahlonega, GA
Posts: 1,503
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 4speed57
I have a Holley 600 on my mild 400 smallblock chevy. I'm also running a descent size cam and that is making the tuning difficult. I couldn't get the idle mixture screws to adjust and I figured out the transfer slots were exposed. I opened the rear secondaries a little and some adjustability has come back. However it is in only one idle mixture screw. If you srew one side in all the way the engine will die. When you screw the other side in it will keep running. I just rebuilt this carb and blew out all of the passages. Would opening the secondaries anymore help? What about drilling the front throttle plates?
Thanks for your time and help.
As some of the other guys mentioned get as much base timing in it as possible and make sure the transfer slots are open no more then .020. If after doing both of these you find it still will not idle with them at .020 or less then you will probably have to drill the holes in the butterflies to get them back down. Starting with our Speed Demon we added the idle-eze feature for cams with durations of .220 and above which allows you to open a valve in the baseplate to get the butterflies back down but with the Holleys you still have to drill. More then likey what you will find when you pull the carb off is that you have gone past the .020 on the transfers slots and when you do this you start to pull that fuel out as well. At that point the mixture screws become ineffective for the most part. Hope this helps.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 01-29-2009, 12:42 PM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 42
Posts: 220
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
Thanks for the replies and help. I pulled the carb off and I noticed since I opened up the rear secondaries the front transfer slots are where they are suppose to be. It still seems to run really rich at idle and like I mentioned before, one idle mixture screw has no effect when you adjust it. I'm going to pull the front bowl off and make sure the gasket is the right one. I'll also blow thru the passage again to make sure its not plugged. I drove my car down the road with the one mixture screw turned all the way in. It ran ok, but hesitated when you snapped open the throttle. The engine should have died when I had the one side turned all the way in.
My combination is a 406sbc, 215 Dart Iron Eagle heads, 11-1CR, Weiand X-celerator intake, Comp Cams XE284 cam, and a Holley 600. Most would agree I need a good dual plane like a RPM airgap and a larger carb. The intake and carb are off a 350 and are practically new. I didn't have the money to buy a larger carb and better intake, so I used what I already had.
It seems this engine has always run rich. The throttle response is sluggish and the spark plugs are usually wet with gas. I have been using Autolite 25 spark plugs. With my 11-1CR I thought I should use a colder plug, but maybe thats why they foul kind of easy. It also seems bumping up the initial timing causes hot restart problems. I have thought about doing the ignition power interupt switch that F-BIRB'88 mentioned. I'm getting closer to fixing the problem. I do think its a combination of timing and carb.
Thanks to all for your help
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 01-29-2009, 07:15 PM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 42
Posts: 220
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
Thanks for the reply and help F-BIRD88. My carb is a cheap model 1850 Holley. The jets are stock, I haven't changed them out. I need to check with Dart and see what plugs they recomend. I have an adjustable vacuum in my garage. I have never locked out my timing before. I've heard people talk about that before, how would you do it? I have a stock HEI.
Thanks again for your time
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 01-30-2009, 01:41 AM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 42
Posts: 220
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
Thanks once again F-BIRD'88, your help is very appreciated. As soon as it gets above freezing I'm going to start on my distributor and carb. At least now I have a direction to go.
Thanks again for your help
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 01-30-2009, 04:59 AM
dawg's Avatar
NAVY VETERAN
 
Last photo:
Join Date: Aug 2004
Location: Colebrook Connecticut
Age: 56
Posts: 920
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 5 Posts
LOL i guess everyone else he didnt bother to thank.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 01-30-2009, 01:30 PM
Member
 
Last photo:
Join Date: Aug 2004
Location: Kentucky
Age: 42
Posts: 220
Wiki Edits: 0

Thanks: 8
Thanked 1 Time in 1 Post
I thought I thanked everyone. F-BIRD'88 was the last to help and he has given me alot of help. I thought I would think he personally.
Thanks to all!
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:
Insurance
Please select your insurance company (Optional)

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
Distributor Tuning and Theory - Part 1 Rick WI Engine 35 04-26-2011 12:38 AM
454 Ignition Timing Question leejoy Engine 56 09-13-2008 08:40 AM
vaccum too low?? 357 with comp 280H cam 357 Cutlass Engine 16 06-29-2008 10:26 AM
running no vacuum advance oregon chevelle Engine 28 02-07-2007 07:17 PM
idle mixture screws 72Orange Engine 14 09-28-2006 01:30 AM


All times are GMT -6. The time now is 02:44 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.