"BACK FIRE BETTY" IN MY 454 - Chevelle Tech
Troubleshooting Diagnosing problems done here.

LinkBack Thread Tools Search this Thread Display Modes
post #1 of 3 (permalink) Old May 27th, 03, 7:23 AM Thread Starter
Join Date: Nov 2002
Posts: 34

Hello there,
I need a little support on my 72 chevelle.
Whats the best way to track down a backfire thru the exhaust?
the motor is probably a 73-74 454 with a new holley 650 with a
hei ignition. I've adjusted the timing to spec, 10 btdc then advanced.
brand new accel 8mm wires, and a cap and rotor, the plugs looked fine.
I get a back fire during accelaration(either a loud bang or a mellow putt-putt). Even idling I can hear
a slight mis-fire. I've only had the car a year and don't much of its history.
I'm wondering if it might be my hei module, cross fire thru the aftermarket wires
or a coil gone haywire. Is there a checklist I might follow to find the problem

MATHER34 is offline  
Sponsored Links
post #2 of 3 (permalink) Old May 27th, 03, 1:34 PM
Tech Team
Join Date: Feb 2003
Location: Lawrence, Kansas, USA
Posts: 168

You have a pretty good list for starters...I would only add that you may also check the valve lash (specifically the exhaust side) to make sure it isn't too tight. If you are holding the valve off the seat a little bit, this can lead to a backfire and also to the valve burning up in short order.

Corey<br /><a href="
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
target="_blank">Corey's 67 Chevelle Page</a>
Corey872 is offline  
post #3 of 3 (permalink) Old Jun 1st, 03, 1:41 PM
Tech Team
Join Date: Sep 2001
Location: Huntington Beach, CA, USA
Posts: 321

Also be sure that when you adjust the timing the vacuum advance is disconnected, and plugged.
Best of luck,

70 Chevelle
68 Camaro
64 Olds Dynamic 88 Holiday Coupe
70mousejob is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:


Old Thread Warning
This Thread is more than 6157 days old. It is very likely that it does not need any further discussion and thus bumping it serves no purpose.
If you still feel it is necessary to make a new reply, you can still do so though.

Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode

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

For the best viewing experience please update your browser to Google Chrome