350 Runs Rich on one side - 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 01-04-2010, 09:38 PM
Cole's Avatar
Now if I could just afford Gas
 

Last journal entry: 1968 camaro SS Clutch build
Last photo:
Join Date: Apr 2004
Location: Los Angeles
Age: 49
Posts: 71
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
350 Runs Rich on one side

This is making me crazy. I have a 1968 350 engine that seems llke it's running rich on just one side (drivers side) of the engine. I know this sounds crazy but it seems true.

Here are the symptoms.
After the car warms up gray smoke starts to come out on the drivers side exhaust. It does not do it at highway speeds, at idle only and it smells like fuel, NOT oil.

Here is what I have done:
Replaced the intake with a Edlebrock Performer EPS and the carb with a Thunder Series 650

Replaced Cap and rotor, also all spark plugs and ran them for 1500 miles and inspected them. They all look like new still (Had to pull them for the compression test anyways)

Ran compression test on all 8 cyls and they pump up evenly to exactly 190 each, in fact they are all almost exactly the same! Engine was warm, all plugs were out and carb removed from intake during test.

Engine Details:
1968 Camaro SS with the 350/295 engine SS package
Camel Hump heads (2 humps) Casting # 3917291
MSD 6A ignition with point distrib
Dual exhaust with no cross connection

Now I am going to ask this at the risk of sounding stupid but is there a chance that the heads are causing this problem?
Thoughts anyone?

Last edited by Cole; 01-04-2010 at 09:59 PM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 01-05-2010, 06:05 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 595 Times in 545 Posts
You undoubtedly have a dual plane intake. This will allow a problem on one side of the carb to show up on only one side of the engine.

I would start with checking real good for any vacuum leaks, and only then continue by balancing the idle mix screws using a vacuum gage, or sensitive tach.

Adjust the screws to get the best idle- the screws should be close to the same number of turns out from *lightly* seated. Don't force the screws in too tight, just lightly seat them before turning them back out. Your manual will have the base settings for them.

Check the rods to see that they are the correct size on both sides. You can do this w/o taking the top off the carb.

If that doesn't help, you may need to open up the carb. It could have a loose jet, a wrong size jet on one side, etc. They are easy to service, the gasket kits are cheap should you tear a gasket.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 01-05-2010, 04:09 PM
Cole's Avatar
Now if I could just afford Gas
 

Last journal entry: 1968 camaro SS Clutch build
Last photo:
Join Date: Apr 2004
Location: Los Angeles
Age: 49
Posts: 71
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Dropped another $50 to Jon/legal fund for good luck on my car today!
Everytime I do my car luck gets better!

I will look at the carb but the intake and carb are only 2 weeks old and I replaced them thinking that would fix this problem. I did use a vacuum gauge to set the screws. I adjusted them until the gauge stopped advancing and then made sure both were set the same number of turns out.
that is why I am so bummed, $700 worth of intake, carb and gaskets and ended up with the same problem. Before it actually had a Weiand intake and Holly carb and that intake was NOT a dual plane and it did the same thing. I am thinking I might need to put a plug wire spark tester on each wire and see if something weird is going on there but other than the rich smoke during long idles periods the car runs perfectly. The only vaccum lines are to the PCV on the valve cover and the power assist on the brake boster and they are new too. I took it all apart last night to do the compression test so I will put it back together and test again. I also just spent $130 on some very nice new MSD ignition wires that arrive today so now we have replaced the following:

New plugs/MSD Wires
New Edlebrock Intake and gasket
New Edlebrock Carb and gasket
New Cap and Rotor
New Points
New Vacuum lines

Putting the points and wires in tonight. hoping it's something with the wires at this point.
the old intake and carb were pretty fugly so not feeling too bad about replacing them and the car runs MUCH better with them on now.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 01-05-2010, 04:25 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 595 Times in 545 Posts
Any chance that a LEAN condition is fooling you? Or a retarded ignition timing?

If either of these or a combo of both is occurring, the exhaust can reek of fuel- even though it's lean or retarded. This is worse w/a big cam.

If incomplete combustion happens, regardless of the cause, the exhaust will smell "rich".

What do the plugs look like? What is the initial timing, and has the timing tab/mark been verified?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 01-06-2010, 07:48 AM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: Springfield, MO
Age: 28
Posts: 1,092
Wiki Edits: 0

Thanks: 5
Thanked 0 Times in 0 Posts
The points probably wont make any difference with the MSD but i think i would switch to an HEI distributor anyways.

Does the engine act like its misfiring or anything? Maybe one cylinder isn't firing and the unburned fuel mixture is pushed into the exhaust and halfway ignited. Otherwise raw fuel must be entering somewhere?

The edelbrock carbs I've had seemed to have problems right out of the box with the float being too high. Also the choke was set wrong, it would never hardly warm up enough to kick the choke off.

If you have a worn engine mount or other problem causing the engine to even slightly lean to one side, any raw fuel entering the intake could run to one side and cause a problem. You mentioned that it only happens when idling for long periods. That sounds like a loading up problem, from a float too high? That problem could easily exist with both carbs. Personally i'd sell them both and put a q-jet back on.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 01-06-2010, 05:08 PM
T-bucket23's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Engine basic condition - how to check Last photo:
Join Date: Aug 2005
Location: Massachusetts
Age: 56
Posts: 4,956
Wiki Edits: 26

Thanks: 2
Thanked 76 Times in 64 Posts
How did the plugs look. Were they all the same.
Were the heads planed or the block decked.
What is the vacuum reading at idle
__________________
Artificial Intelligence is no match for Natural Stupidity



Chet
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
V8 w/ carburetor + eletric fuel, runs too rich. Do I need a fuel pressure regulator? 5_speed Engine 18 10-25-2009 01:51 PM
89 GMC 350 Running Rich bushman Introduce Yourself 2 06-16-2009 09:16 AM
TH 350 lost 3rd gear and reverse is weak junior stocker Transmission - Rearend 1 05-29-2009 04:20 PM
new block mikey1476 Engine 8 04-12-2009 09:34 PM
hot side, 350 tpi engine runs hot on one bank? Ellisb Engine 16 10-27-2002 06:28 AM


All times are GMT -6. The time now is 09:55 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.