350 idles too fast - 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 03-11-2010, 08:21 PM
Aerotech's Avatar
Registered User
 
Last photo:
Join Date: Oct 2009
Location: Brandon, MS
Posts: 74
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
350 idles too fast

I fired up my little roadster after a short Mississippi winter and though it was well set up when I parked it, it now idles too fast. Cable and linkage are loose, idle screw off the stop, choke off, everything for a slow idle and it won't settle down. I don't want to idle it down with ignition timing and kill the performance.

It's just a mild 350 with Comp 252, Holley 600, Weiand dual-plane, Delco HEI, and 1.72/1.50 Power Pack heads. No vacuum leaks. Why won't it idle down?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-11-2010, 08:35 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 49
Posts: 10,121
Wiki Edits: 0

Thanks: 1,294
Thanked 575 Times in 423 Posts
Look into the carb and make sure the bottom butterfly's aren't stuck open..
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-11-2010, 09:07 PM
Aerotech's Avatar
Registered User
 
Last photo:
Join Date: Oct 2009
Location: Brandon, MS
Posts: 74
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
Nope. Air cleaner off, everything cool. Haven't touched a thing since parking it.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-11-2010, 09:08 PM
Registered User
 
Last photo:
Join Date: Nov 2009
Location: no longer here
Posts: 293
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
also check the float level as if its a little high it will spill over and cause the same thing .
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-11-2010, 09:25 PM
Aerotech's Avatar
Registered User
 
Last photo:
Join Date: Oct 2009
Location: Brandon, MS
Posts: 74
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
Float level checks good. Set dry and confirmed wet.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-11-2010, 09:34 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Could be nothing more than a sticking mechanical advance. I'd suggest popping the distributor cap and checking it out.

A vacuum hose that's off or split could lean it enough to raise the idle.

Check the PCV valve to be sure it rattles.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-11-2010, 09:51 PM
Aerotech's Avatar
Registered User
 
Last photo:
Join Date: Oct 2009
Location: Brandon, MS
Posts: 74
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
The flyweights don't come in at idle and the car has been driven enough to shake out any stickiness. It's the same setup that worked great when it was parked. I think it will eventually settle out but I am reluctant to mess with a good setup. It had a rotten vacuum cap which I replaced but there was no leak so it made no difference.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 03-11-2010, 10:07 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Quote:
Originally Posted by Aerotech
The flyweights don't come in at idle
If they ever advanced when you first started it up this season (like if you blipped the throttle at start-up), then they didn't come back to rest fully- they'd still be advanced.

Easy enough to check.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 03-12-2010, 12:26 AM
sqzbox's Avatar
My pipes are my music
 
Last photo:
Join Date: Sep 2009
Location: indiana
Age: 64
Posts: 2,938
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
High rpm on idle circiut

Disconnect the vacuum advance hose on the distributor, plug the hose and see what it does.

Are you sure the hold down clamp on the dist. is tight?

If you have the idle screw off the stop and pull the throttle closed, does it make a difference?

It's hard for the engine to idle high on the idle circuit by itself and if there is no fuel dripping out of the booster more than likely, it's a timing issue.

After sitting for a period of time, it's a good idea to lubricate the throttle linkage and rods at the base of the carb. Also, the weights in the distributor.

Sooner or later, your going to have to take the cap off the dist. so do it now!
You don't have to change your setup to check it out.

Quit eliminating what you think is right and check to make sure it is.
I've found that the one thing I didn't look at was the very thing that was wrong and ended up kicking myself for it in the end.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 03-12-2010, 05:23 AM
Aerotech's Avatar
Registered User
 
Last photo:
Join Date: Oct 2009
Location: Brandon, MS
Posts: 74
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
I've checked everything you mentioned except the advance. It's no big deal to pop the cap and give the flyweights a shot of lube. They've been through many cycles and never stuck before so I just assumed they were ok.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 03-12-2010, 08:52 AM
Frisco's Avatar
Glad To Be Here
 
Last photo:
Join Date: Nov 2002
Location: Canton, North Carolina
Age: 72
Posts: 2,244
Wiki Edits: 0

Thanks: 0
Thanked 8 Times in 8 Posts
Something else to look at.

After the choke fully opens, 'blip' the throttle to get the throttle linkage off the high idle shoulder of the throttle cam linkage. If it stays on that portion of the cam linkage the idle will be high and the throttle stop screws will be off the stop as well. The linkage could be 'dirty' and sticking as well.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 03-12-2010, 09:06 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
I would agree- the easiest thing to look at, is if the curb idle screw is in contact with the carb linkage- w/o ANY gap whatsoever.

If the fast idle cam is holding the throttle open or if there's something binding in the choke flap or its linkage or counterweight, for instance- there will be a gap between the curb idle screw and the linkage.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 03-12-2010, 09:09 AM
sqzbox's Avatar
My pipes are my music
 
Last photo:
Join Date: Sep 2009
Location: indiana
Age: 64
Posts: 2,938
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
If the choke plate is fully open, the fast idle screw should be off the high point of the cam, manual or auto. tapping the throttle only opens the choke a little and in turn drops the fast idle cam down to the next lower step.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 03-12-2010, 03:23 PM
Aerotech's Avatar
Registered User
 
Last photo:
Join Date: Oct 2009
Location: Brandon, MS
Posts: 74
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
Problem solved. Thanks guys! The car has no choke, so of course that's not it. I think somehow the throttle wasn't returning enough to get off the high idle step, even when moving the linkage by hand. Yesterday the idle screw was off the stop but today it was touching so I could back it off a turn. Good as new!
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 03-12-2010, 11:43 PM
sqzbox's Avatar
My pipes are my music
 
Last photo:
Join Date: Sep 2009
Location: indiana
Age: 64
Posts: 2,938
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
So what your saying is the choke plate was removed but the fast idle cam linkage wasn't disabled? AAaaarrr! Bet you never do that again! Have fun!
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
Distributor Tuning and Theory - Part 1 Rick WI Engine 35 04-26-2011 12:38 AM
Cam/Lifter Question about Ramjet 350 Jake Harsha Engine 20 07-07-2010 06:22 AM
Bog/Black Smoke on Olds 350 at 3000 rpm JohnTN Engine 4 03-17-2009 11:39 AM
possible 350 block purchase - comments please idrva55 Engine 17 12-09-2007 09:29 PM
348 or 350 delimma 62ImpalaSS Engine 12 05-17-2006 11:03 PM


All times are GMT -6. The time now is 05:21 AM.


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.