Backfire through CARB??? - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 10 (permalink) Old Apr 28th, 11, 07:50 AM Thread Starter
Ty
 
Join Date: Mar 2011
Location: Toronto
Posts: 3
Backfire through CARB???

Hi there,

Im new here, as i just bought a 69 Camaro.

My car has a Merlin 509 BB, with a Holley Carb. I just started driving it. Now... I noticed when I shut the car off, there is a loud backfire, a puff of black smoke out of the cowell induction... obviously out from the K&N air cleaner.

It doesnt happen all the time. I noticed the same noise and puff on a start up... i think cuz it was cold...

I sounds like a backfire. what is the cause for this? Is this a bad sign for things to come?

Please help me....
wrxninja is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old Apr 28th, 11, 12:27 PM
Senior Tech
Terry
 
Join Date: Jan 2010
Location: SF Bay Area
Posts: 561
Re: Backfire through CARB???

Poor ignition timing can cause carburetor popping when the intakes valves are not properly closed before fuel combustion.

Both optimists and pessimists contribute to society. The optimist invents the automobile, the pessimist seat belts, head rests, disc brakes, and air bags.
IRON MAN is offline  
post #3 of 10 (permalink) Old Apr 28th, 11, 01:18 PM
Senior Tech
Wes
 
Join Date: Dec 2003
Location: Leander, TX
Posts: 2,762
Re: Backfire through CARB???

To be clear, it pops through the carb 'after' the ignition is turned off?
Straight-line-69 is offline  
 
post #4 of 10 (permalink) Old Apr 28th, 11, 01:48 PM
Tech Team
George
 
Join Date: Nov 2005
Location: North Carolina
Posts: 63
Re: Backfire through CARB???

Sounds like timing might be a little high.If you are running an automatic trans you can try putting in gear holding the brake and shutting engine off just dont forget to put back in park or if manual trans ease out on clutch to put load on engine and shut it off. hope you can find the problem.
z28station is offline  
post #5 of 10 (permalink) Old Apr 28th, 11, 01:52 PM
Senior Tech
Ron
 
Join Date: Nov 2006
Location: North Channel Lake Huron
Posts: 3,934
Re: Backfire through CARB???

You can get Run On & Carb Popping if the Throttle Plates are not closing or not adjusted properly when shutting down.

Z15CAM - There was a Viper in my Rear View
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

This was my 70 1/2 Z28

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Z15CAM is offline  
post #6 of 10 (permalink) Old Apr 28th, 11, 04:01 PM
Senior Tech
Dan Ensign
 
Join Date: Jan 2007
Location: Claverack,NY
Posts: 366
Re: Backfire through CARB???

Nobody else has said it so I'm gonna, we need pics. How does it run other than that, also check that there isn't any fuel leaking down the carb from high float levels. Sounds like a timing issue though.

Dan E.
69 SS396 4spd. 4.10posi. x66 coupe
Dan E. is offline  
post #7 of 10 (permalink) Old Apr 28th, 11, 09:26 PM
Senior Tech
Wes
 
Join Date: Dec 2003
Location: Leander, TX
Posts: 2,762
Re: Backfire through CARB???

I don't see how it's a timing issue if the popping happens "after" the ignition is turned off.
Straight-line-69 is offline  
post #8 of 10 (permalink) Old Apr 28th, 11, 10:27 PM
Senior Tech
AJ
 
Join Date: Jul 2006
Location: AUSTIN TEXAS
Posts: 3,842
Re: Backfire through CARB???

You should put a light on it to see what the timing is doing...
BTW, I had the wires wrong on my cap once, wouldn't run or idle, flames out of the carb run on etc... Moved the wires back on the cap, fixed it.
If it's retarded the plugs/cylinders will be hot enough to pre ignite the fuel.

The only Mustang I'd ever own is a Fender.

'68 333" Camaro
'14 5.0 Mustang
ace's68 is offline  
post #9 of 10 (permalink) Old May 1st, 11, 04:49 PM
Tech Team
WrenchingAce
 
Join Date: Nov 2004
Location: SLC, Ut
Posts: 94
Re: Backfire through CARB???

Sounds like a bad Magnetic Pickup to me. I'll bet it has an MSD Distributor...if it does then you should pull the dist cap off and take a look inside at the magnetic pickup assembly...it's probably all corroded.
speedfreak2 is offline  
post #10 of 10 (permalink) Old May 2nd, 11, 05:01 AM
Senior Tech
darrell
 
Join Date: Feb 2011
Location: texas
Posts: 1,202
Re: Backfire through CARB???

all good points- i would set timing first -re set idle mixture screws 2nd with vacuam gauge and chek for fuel dripping thru ventures on carb
97Z4C is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro 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:
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.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










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