Backfiring Question - 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 03-23-2008, 02:19 PM
bluesman123's Avatar
Member
 
Last photo:
Join Date: Nov 2002
Location: Bay Area, California
Age: 68
Posts: 593
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Afterfiring Question

I have just completed my first total rebuild of a Chevy 383, and now I hear occasional afterfiring through the right exhaust pipe (no H or X pipe crossover). The engine runs a Holley 670 Street Avenger and has the GMPP Hot cam but with 1.5 rockers instead of the 1.6. There also seems to be a little roughness between 2000 and 3000 RPM. I have pulled all the plugs and they all look the same...not enough time on them to tell much. The timing was initially set at about 12 degrees and I haven't gone back to check on that. I set the valves with the engine off but it was cold when I did it, if that makes a difference.

I would really appreciate any suggestions on where I should start looking.

Dave

    Advertisement

Last edited by bluesman123; 03-23-2008 at 03:51 PM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-23-2008, 06:07 PM
richard stewart 3rd's Avatar
Registered User
 

Last journal entry: 351W rebuild
Last photo:
Join Date: Jan 2006
Location: tremont, pa.
Age: 69
Posts: 2,217
Wiki Edits: 0

Thanks: 13
Thanked 15 Times in 14 Posts
Hi,
Check for vacuum leaks, especially the intake gaskets, & vacuum lines. Back fire through the
exhaust is caused by an air fuel ratio imbalance,
if it's to lean you might get a pop in the intake,
to rich may get one out the exhaust.
Good luck,
Rich
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-23-2008, 06:20 PM
bluesman123's Avatar
Member
 
Last photo:
Join Date: Nov 2002
Location: Bay Area, California
Age: 68
Posts: 593
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Oh man this is so embarassing!! I found the problem...I had swapped the wires for 6 and 8. I can't believe how much time I spent doing and re-doing everything. So everything solved...runs great!

Dave the Doofus.............
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-23-2008, 09:05 PM
richard stewart 3rd's Avatar
Registered User
 

Last journal entry: 351W rebuild
Last photo:
Join Date: Jan 2006
Location: tremont, pa.
Age: 69
Posts: 2,217
Wiki Edits: 0

Thanks: 13
Thanked 15 Times in 14 Posts
Hi,
Glad you found the problem.
Rich
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-23-2008, 10:32 PM
400smb_s10's Avatar
Back Yard Junky :)
 
Last photo:
Join Date: Mar 2007
Location: Around the Corner from the middle of nowhere... Arden Ontario
Age: 28
Posts: 368
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
dont be embarrassed my girl friend has a 01 alero and it would start if you boosted it and wouldnt start or put lights on the dash when the key was on. I found out when I replaced the battery I didnt tighten the positive battery terminal all the way and it rattled loose, spent $390 on a new alternator for a loose battery wire ...!
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-24-2008, 07:07 AM
Double_v23's Avatar
Horsepower Enthusiast
 

Last journal entry: Finished BMOD001FH
Last photo:
Join Date: Jul 2007
Location: Mooresville, NC
Posts: 1,495
Wiki Edits: 0

Thanks: 0
Thanked 4 Times in 4 Posts
Just a quick question...you mentioned you had 1.5 rockers "instead of the 1.6" is that something specific to the cam you chose? Small block Chevy's come with 1.5's stock. I am just a little confused by the wording.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-24-2008, 10:40 AM
bluesman123's Avatar
Member
 
Last photo:
Join Date: Nov 2002
Location: Bay Area, California
Age: 68
Posts: 593
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
You're right, they do usually come with 1.5 rockers. The GMPP Hot cam was introduced as part of an upgrade kit, originally for LT1s I think, and that kit comes with 1.6 rockers. I might add that this kit does not carry a CARB approval number. Anyway, as a $$ saver, I put the heads together with some stock stamped-steel 1.5 rockers I had. Eventually I will upgrade to 1.6 rollers, mostly for the cool factor I suppose. The heads are the SDPP modified vortecs so they can take the extra lift.

Anyway, I managed to put maybe 20 miles on it last night and it runs great. A little lumpy at idle but very torquey at low RPMs.

Dave
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
383 stroker 73monte Engine 11 05-07-2014 08:08 AM
supercharger.... 73monte Engine 16 07-24-2010 10:27 AM
question about a previouse question elrod1030 Engine 6 03-10-2010 07:35 AM
Ignotion Set-ups Native Gearhead Engine 8 11-29-2003 01:20 PM
nitrous 69BiRd Engine 2 11-28-2003 10:33 PM


All times are GMT -6. The time now is 03:04 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.