...

Go Back   Lateral-g Forums > Technical Discussions > Engine
User Name
Password



Reply
 
Thread Tools Display Modes
  #1  
Old 03-08-2017, 11:46 AM
IndyNova's Avatar
IndyNova IndyNova is offline
Senior Member
 
Join Date: Sep 2009
Location: Avon, In
Posts: 303
Thanks: 0
Thanked 0 Times in 0 Posts
Default LS Backfiring issue

Hi guys, here's what I have: Stock bottom end 6.0, 241 heads, new ls7 lifters, new trays, stock rocker arms, custom comp cam. New Crank and cam gear, and new timing chain. I have stock pushrods (I know I need different ones with the cam-more on that in a second) ls6 intake, base tune by Mike Noris motor sports.
So, after starting with the new cam, ran great for 1:30 and I shut it off. Went to start it up after 30 minutes or so, and it started backfiring through the exhaust. Never did it in startup or while running, all the pushrods were straight, all valves checked out (applied air into the cylinders to check for leakage through intake or exhaust valves) Prior to this, the car started and ran fine.

I'll post both the old and new cam specs in comments. Thanks all!
__________________
https://facebook.com/Protour69Nova
69 Nova-Ridetech, LS
Reply With Quote
  #2  
Old 03-08-2017, 11:47 AM
IndyNova's Avatar
IndyNova IndyNova is offline
Senior Member
 
Join Date: Sep 2009
Location: Avon, In
Posts: 303
Thanks: 0
Thanked 0 Times in 0 Posts
Default

New Cam specs
__________________
https://facebook.com/Protour69Nova
69 Nova-Ridetech, LS
Reply With Quote
  #3  
Old 03-08-2017, 11:48 AM
IndyNova's Avatar
IndyNova IndyNova is offline
Senior Member
 
Join Date: Sep 2009
Location: Avon, In
Posts: 303
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Old cam specs
__________________
https://facebook.com/Protour69Nova
69 Nova-Ridetech, LS
Reply With Quote
  #4  
Old 03-08-2017, 02:18 PM
Che70velle's Avatar
Che70velle Che70velle is offline
Senior Member
 
Join Date: Aug 2012
Location: Dawsonville Georgia
Posts: 2,219
Thanks: 609
Thanked 157 Times in 109 Posts
Default

Too much lifter preload. It can be off by a smidge, and cause this.
__________________
Scott
---------------------------------------------------------------
70 velle' on custom chassis w/custom RideTech coilovers, RED sleeved 434” with Mamo 265’s, F-body Magnum, 12 bolt 3:73, wilwood 6/4's, bla, bla, bla...build. thread https://lateral-g.net/forums/showthread.php4?t=39631
New 434” engine build here https://ls1tech.com/forums/generatio...ved-block.html

Thanks Dad!!

My Chevelle is old school... It has a belt driven power steering pump.
They're 17's, but I keep em clean!
Reply With Quote
  #5  
Old 03-12-2017, 08:22 AM
71RS/SS396's Avatar
71RS/SS396 71RS/SS396 is offline
Senior Member
 
Join Date: Jan 2009
Location: Wake Forest,NC
Posts: 870
Thanks: 1
Thanked 5 Times in 4 Posts
Default

If everything mechanical with the valvetrain checked out ok my first guess would be the cam pulse is missing from either the sensor being bad or the wiring has a problem but they will usually eventually start if this is the case if you keep cranking.
Reply With Quote
  #6  
Old 03-14-2017, 10:32 AM
IndyNova's Avatar
IndyNova IndyNova is offline
Senior Member
 
Join Date: Sep 2009
Location: Avon, In
Posts: 303
Thanks: 0
Thanked 0 Times in 0 Posts
Default

So I found the issue.. the wires were crossed in an coil extension harness I got to relocate the coils. I never thought to look there since it ran fine on initial setup.
__________________
https://facebook.com/Protour69Nova
69 Nova-Ridetech, LS
Reply With Quote
  #7  
Old 03-14-2017, 03:47 PM
Che70velle's Avatar
Che70velle Che70velle is offline
Senior Member
 
Join Date: Aug 2012
Location: Dawsonville Georgia
Posts: 2,219
Thanks: 609
Thanked 157 Times in 109 Posts
Default

Thanks for the follow up. All too often, threads like this die off with no explanations.
__________________
Scott
---------------------------------------------------------------
70 velle' on custom chassis w/custom RideTech coilovers, RED sleeved 434” with Mamo 265’s, F-body Magnum, 12 bolt 3:73, wilwood 6/4's, bla, bla, bla...build. thread https://lateral-g.net/forums/showthread.php4?t=39631
New 434” engine build here https://ls1tech.com/forums/generatio...ved-block.html

Thanks Dad!!

My Chevelle is old school... It has a belt driven power steering pump.
They're 17's, but I keep em clean!
Reply With Quote
  #8  
Old 03-14-2017, 04:33 PM
IndyNova's Avatar
IndyNova IndyNova is offline
Senior Member
 
Join Date: Sep 2009
Location: Avon, In
Posts: 303
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Yeah I was completely dumbfounded by it. I don't get how it ran for a minute and half, and then the next time I started it, it was popping and backfiring. Would've saved me hours if I'd have started there...lol
__________________
https://facebook.com/Protour69Nova
69 Nova-Ridetech, LS
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump


All times are GMT -5. The time now is 09:36 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright Lateral-g.net