Tech Questions/Advice
115235 backfiring - top causes? [cgranju] (Mon Jan 26 18:02:22 2004)
115236 My vote is for the leaky exhaust [mtharp] (Mon Jan 26 18:18:20 2004)
115238 Re: backfiring - top causes? [hotdamn] (Mon Jan 26 18:41:12 2004)
115239 Re: backfiring - top causes? [early124] (Mon Jan 26 19:12:57 2004)
115244 haha [hotdamn] (Mon Jan 26 20:58:30 2004)
115248 Re: backfiring - top causes? [cgranju] (Tue Jan 27 5:27:11 2004)
Message#: 115235
Subject: backfiring - top causes?
From: Chris G [cgranju]
(chris@fiataccompli.com)
Date: Mon Jan 26 18:02:22 2004
Replies: 115236, 115238
one of my coupes (this one particularly 'rode hard & put up
wet') has developed a nasty backfiring habit. Actually, it's
had it for years, but I've just gotten it back in service as an
occaisional driver & it's no fun having people think I'm
shooting at them. Here's what I know about it; It currently
runs rich, it has headers & a generally leaky exhaust. 1800
engine w/ hot cams, Spider2000 ignition & 34DMSA carb. The only
time it backfires is when coming off extended high revs & then
not every time. So, I'm thinking the key points are running
rich-unburned fuel; air leaks sucking oxygen into the header
tubes & perhaps something timing-related. I have not checked
compression yet....just looking for ideas to gel. thanks
Chris G
------------------
5 124s, 1 X 1/9, lots of parts, oscillating chaos
Knoxville, TN
Message#: 115236
Subject: My vote is for the leaky exhaust
From: Mike T [mtharp]
(metharp@cox.net)
Date: Mon Jan 26 18:18:20 2004
In-Response-To: 115235
Mike Tharp - Wichita, KS
'81 2000 Spider FI
'02 Jeep Grand Cherokee Overland
Message#: 115238
Subject: Re: backfiring - top causes?
From: dan [hotdamn]
(dan@saaborama.com)
Date: Mon Jan 26 18:41:12 2004
In-Response-To: 115235
Replies: 115239
if you mean popping from the exhaust, then I vote exhaust leaks.
if you mean from the intake, I'll go with too lean, tight valve,
cam timing, ignition timing, or hubcap gasket.
-dan
'68 124 spider (mine)
'72 124 spider (mine)
'78 124 spider (mine)
'81 124 spider (mine)
some saabs, a jeep, bla bla bla
Message#: 115239
Subject: Re: backfiring - top causes?
From: Pete Angel (Colo Sprgs, CO, USA) [early124]
(pete.angel@att.net)
Date: Mon Jan 26 19:12:57 2004
In-Response-To: 115238
Replies: 115244, 115248
hi dan - short of tossing that leaky header as far as possible,
couldn't chris lean the idle circuit, retard the igntion timing
a bit and/or increase the cam duration to reduce the afterburn?
-----------------------------------------------------
Pete Angel
Mira Forum member since 1998
FLU Member #1962
eBay ID: AngelsinCO
-----------------------------------------------------
Message#: 115244
Subject: haha
From: dan [hotdamn]
(dan@saaborama.com)
Date: Mon Jan 26 20:58:30 2004
In-Response-To: 115239
yeah, that's why I added the hubcap bit. I bet I missed
*something.
*the actual cause
-blanket dan
'68 124 spider (mine)
'72 124 spider (mine)
'78 124 spider (mine)
'81 124 spider (mine)
some saabs, a jeep, bla bla bla
Message#: 115248
Subject: Re: backfiring - top causes?
From: Chris G [cgranju]
(chris@fiataccompli.com)
Date: Tue Jan 27 5:27:11 2004
In-Response-To: 115239
well, most of it needs tossing actually-or at least major
refurbish....but this one's kind of the 'mad max' coupe right
now (ultimate plan is to install the clean, tight drivetrain
from a '73 Spdier I parted out a few years ago) - a BC w/ two
headlights, no grill, no bumper, turn signals duct-taped to the
bumper mounts, ...so, well, basically I'm thinking of doing the
easy stuff to make it reasonably alright to drive....so timing,
tightening up leaks, & carb R/R are good prospects. thanks for
the thoughts.
Pete are you anti-header or just anti-leaky header. I'm not a
big fan of the latter either....even though it seems like the
most popular type!
Chris G
Pete Angel (Colo Sprgs, CO, USA) wrote:
: hi dan - short of tossing that leaky header as far as
possible,
: couldn't chris lean the idle circuit, retard the igntion
timing
: a bit and/or increase the cam duration to reduce the afterburn?
: -----------------------------------------------------
: Pete Angel
: Mira Forum member since 1998
: FLU Member #1962
: eBay ID: AngelsinCO
: -----------------------------------------------------
Chris G
------------------
5 124s, 1 X 1/9, lots of parts, oscillating chaos
Knoxville, TN