When I got my '80, the air pump hose was disconnected, and when I hooked
it back up, I got the same backfire. It also has a Weber carb, and I was
told at the time that the air pump was incompatible with a Weber. I was
a bit concerned with the vacuum loss at the end of the exposed air pump
hose, so instead of removing the pump, I removed the drive belt and
reconnected the hose. The end result was a noticeable increase in power,
especially on acceleration.
As to the cat converter, I keep seeing the GO'Bs on HPTV replacing stock
converters on various muscle cars with (street legal) "high performance"
ones as part of an exhaust upgrade. Anyone know if similar converters
are available for Spits?
Rick Gregory wrote:
> Atwell:
>
> My '77 has this exact same problem. It backfires while
> idling down from high RPMs. I removed the air pump
> belt to eliminate the back firing, but don't like the
> idea of removing emission devices. Plus, my air pumps
> works good I don't want it to freeze up.
>
> I thought maybe the check-valve on the tube behind the
> air pump was shot.... allowing the back-fire.
>
> How could the catalytic converter be the cause of the
> problem? Restricted flow?
>
> --Rick
>
> --- Atwell Haines <carbuff@nac.net> wrote:
> >
> > At 07:52 PM 6/13/99 -0400, Sam Gentry wrote:
> > >We just got the 80 spit running and it works well
> > EXCEPT: When we rev the
> > >engine and let it coast down it backfires and gets
> > very rich. Works great
> > >if we eliminate the air pump. Any ideas? I would
> > like to keep the
> > >emission stock if possible.
> >
> > Sam,
> >
> > Chances are that your catalytic converter is shot.
> > That's an expensive
> > repair. :(
> >
> > I have left the air pump disconnected on mine
> > because of that. Plus, my
> > air pump is a bit noisy also. (Another expensive
> > repair) It passed the NJ
> > idle emissions test that way... :)
> >
> > Also, there is an off chance that your
> > bypass/deceleration valve (front
> > side of carb) has been blanked off.
> >
> > Atwell Haines
> > '79 Spitfire
> > Succasunna, NJ USA
> > "If horrific means to make horrible, doesn't
> > terrific mean to make
> > terrible?"
>
>
>
--
"History shows again and again, how nature points out the folly of man."
-R. A. Woodward (conn@wctc.net)
|