[Top] [All Lists]

Re: Vacuum advance, pt. 2

To: (Todd Mullins)
Subject: Re: Vacuum advance, pt. 2
From: Craig Wiper <>
Date: Tue, 16 Jan 1996 19:17:37 -0800
At 03:46 PM 1/16/96 -0600, you wrote:
>Hi, all.  I'm the one who asked about dizzy vacuum advance units.

>New question:  Backfiring.  I don't quite understand it.  My exhaust
>makes a raspy, popping sound upon overrun.  I had assumed that it was
>unburnt fuel travelling through the pipe and exploding when it
>encountered the outside air.  Others have told me that backfiring is due
>to a lean mixture.  Which is right?  I believe my carbs (dual HIF4s) are
>adjusted properly, though I don't have any of those fancy tools or clear
>spark plugs.  I use the method outlined in the Workshop Manual: lean
>best idle plus a quarter-turn rich.  But since I'm now sure that my gulp
>valve is operative, I can't think of anything else that might cause
>backfiring (I have solid throttle plates).  Any gurus?  Denise?
>>Todd Mullins

Hi Todd, My '74 B used to backfire before I removed the smog equipment. When
I reinstall the  equipment (by the way I have acquired as many new smog
parts as possible) the backfiring returns, but ever so slightly since making
sure that all components in the system are in good working order. I believe
that the backfiring comes from the injection of air into the system.

Craig Wiper
early '74B

<Prev in Thread] Current Thread [Next in Thread>