Back Firing
 

I have a 69 Z with a smog pump and chambered exhaust that back fires when I let off the gas or downshift. Does anyone know what the cause could be?

John

Re: Back Firing
 

bad diverter valve or vacumn signal

Re: Back Firing
 

John, What car did you buy? Any pictures? Sam

Re: Back Firing
 

Possible exhaust leak

Re: Back Firing
 

http://i708.photobucket.com/albums/w...7/DSCN2120.jpg

Re: Back Firing
 

I'm no expert....but I would vote for lean. Colder temps have more oxegen in the air...you need to put more fuel in the carb to equal this out. I have a baseline for my car and adjust air bleeds up or down 1 1/4 turn before changing jets.

Re: Back Firing
 

I thought all smog set ups backfired to a point...which is one of the reasons that people took them off... https://www.yenko.net/ubbthreads/imag...mlins/hmmm.gif https://www.yenko.net/ubbthreads/imag...lins/dunno.gif

Re: Back Firing
 

Judging by the hood, it's a cross ram. My vote, Too fat!
Excess fuel gets in the exhaust, A.I.R. does its job, wham...backfire! M.O.O. and $0.02 https://www.yenko.net/ubbthreads/imag...lins/dunno.gif
Tim

Re: Back Firing
 

NIZZZE car John! https://www.yenko.net/ubbthreads/imag...iggthumpup.gif

Re: Back Firing
 

i wish it was a cross ram.wens i will block up all the holes in the exhaust manifold and try that.

john