Atwell Haines wrote:
> At 10:09 PM 6/13/99 -0400, Kirby T. Kenyon wrote:
> >Atwell,
> >
> >I also have this problem with my '80 Spit (which has a '78 Carb). I have
> >no catalytic converter. I'm curious why this problem might implicate the
> >converter?
>
> The converter is hot and will ignite unburned gas on overrun...ESPECIALLY
> when an air pump is shooting air in to make the embers glow! Melted-down or
> disintegrated cat elements will have hot spots that amplify the backfiring
> tendancy.
>
> Does your car have the air pump going into a single pipe in the exhaust
> manifold, or into four small pipes on the cylinder head? In the latter
> system Triumph fitted a 'gulp valve' whose function is to divert the air
> pump flow to the atmosphere on overrun. My 5.0 Mustang V8 has a similar
> system.
>
> >
> >Also, do you know if there are any problems from not using the air pump?
> >I've put 2 used ones on the car since last fall. I hope that the last one
> >will work OK but don't really want to spend the $ to get a new one.
> >
> >You always seem to know these answers.
>
> <blush> I gotta say that I do THINK about these things a lot... and I tend
> to over-analyze stuff very often!
>
> Be that as it may, My Spit has the same tendancy to backfire if the air
> pump is connected. (I know my Cat is shot because the PO's carb had a bad
> jet and was running rich for gawd knows how long.)
>
> I have plugged the air pump pipe just downstream of the check valve. The
> air pump belt has been removed. I give it a spin once in a while to keep
> the pump 'limber'. If need be I can restore it to 'operational' in 5
> minutes (for our states smog check, for example).
>
> I have run the car that way for about 3000 miles, with no apparent downside.
>
> Bob Norway taught me this stuff last year. He has had this problem on
> several Spitfires.
>
> I'd say remove or disable the pump and don't worry about it. Just plug the
> pipe so that exhaust gases don't cook the bearings in the pump.
>
> Does your Spit have a header installed?
>
> Atwell
Atwell,
I do appreciate being named as your mentor, however I think you confused me with
someone else. While I too had to disconnect my air pump, I never (to my
recollection, anyhow) discussed it on the list, and I've only had two spits, one
hardly long enough to get to know....LOL.
Now, in connection with disabling air pumps (I too pulled the pump and plugged
the hose), I found after discussions with Joe Curry and others on replacing my
mechanical fuel pump with electrical, that the air system ALSO replaced the oil
breather system. B/L sealed the hole in the block where the oil breather used to
be hooked (just a tube pointing down) and pressure was now relieved by the AIR
system. I found this out after trying to figure out why I should hook a tube to
the cover over the hole of the old fuel pump. It was to relieve the internal
pressure built-up by a closed system oil system.
After completely removing the AIR system plumbing, blocking the holes with brass
bolts, removing the EGR plumbing and sealing appropriate holes, AND having a
hose going from the fuel pump access hole to the charcoal canister (to relieve
pressure), doing a complete valve job and replacing all gaskets, including the
oil pan gasket, I now have NO OIL LEAKING!!! It's absolutely incredible. You can
refer to Joe Curry's article on Tom Shirley's web site at
http://www.geocities.com/MotorCity/Speedway/1080/stopoilblowing.html for more
info on the subject of blowing oil.
Cheers,
--
Bob Norway
Rockledge, Florida
Home Page http://www.geocities.com/CapitolHill/Lobby/5953/mypage.html
ICQ# 3752712
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1976 Triumph Spitfire 1500
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