RE: [alfa] Exhaust temperature

["Peter Webb" <webb.p@xxxxxxxxxxx>]

Those temps are fine.   You can run to 1500DegF.   High EGT is indicative of
a lean mixture or ignition timing.   Check the ignition timing again through
the advance curve.  Make sure the weights aren't binding in the dizzy.  The
WB02 will tell you what your AFR is, I expect it to show 12.5:1 under
acceleration and 14:1 at cruise.   IME, the Spica pumps hardly ever go lean
if set up properly.  If the AFR's show ok, the problem is ignition.  If
you're running one of those horrible 70s Marelli points distributors, dump
it.   You can retro-fit a later Spider inductive or hall-type pickup on an
HEI-4 module.   Very simple to set up.   The HEI requires an unductive
pickup but can be run from a hall sensor with a 1K resistor inline to the
pickup (-) line.   Motronic Spider dizzies have a hall-sensor in them.   Not
sure what kind of sensor the RML or MSD(Crane) uses.  The HEI-4 modules are
about $20.   You can use any coil with it.   The Motronic Spiders use a
special coil because of the Bosch transistorized ignition module.   The
HEI-4 has dwell built in.  You could also try an HEI-7 module and an
external timing control box.

BTW, the MegaJoltLite (or MSnS) will control both the HEI-7 and Bosch
transistor module with electronic advance control based on RPM and MAP.  See
the MSnS Yahoo group files section for wiring diagrams and how-tos.  Get
t.he Bosch module from a ML4.1 164

-Peter


> -----Original Message-----
> From: owner-alfa@domain.elided [mailto:owner-alfa@domain.elided]On Behalf Of
> Jon Pike
> Sent: Sunday, March 28, 2004 3:12 AM
> To: alfa-digest@domain.elided
> Subject: [alfa] Exhaust temperature
>
>
> Hi all..
>
> Another quick question.. this one for the mixture guru's..  Just stuck a
> thermocouple probe into my exhaust just upstream of my cat converter,
> and am reading temp's for the first time.  Curious on what is a "normal"
> range.  I know that one can get a gross idea of mixture by the temp,
> with a lean mixture causing it to go high.
>
> I'm seeing a range of 500-700C, (932-1292F!) with 570-600 being average
> during cruising,  and going as high as 700 during a WOT romp thru the
> gears..  Seems kinda high, but I don't know..   I have the thermocouple
> in the exhaust path, but not touching the ceramic matrix of the
> converter.  It's probably an inch away from it, though.. so hard to say
> if it's very hot and radiating extra heat into my reading..    I
> adjusted my Spica on a friend's exhaust analyzer.. think I'm running
> about 1-1.5% CO now, but it may be leaner than that in normal on the
> road operation..  Was reading about 3%, and it felt a bit more
> solid then..
>
> Waiting on getting a WBO2 sensor and controller, then I'll be better
> able to know where I'm at... so this is playing around and curiosity
> satisfaction till it gets here.
>
> Jon
> 77 Spider
> Irvine, CA
> --
> to be removed from alfa, see /bin/digest-subs.cgi
> or email "unsubscribe alfa" to majordomo@domain.elided
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided