I've kept quiet about this because I have no direct experience on Triumphs,
but I've done a lot of exhaust gas temp work building racing engines for
bikes. You want the probe as close to the exhaust valve as you can get it,
because you don't want the dynamics of the pipe to interfere. You're looking
for relative readings, cylinder to cylinder, and absolute readings to be
sure your exhaust valves aren't about to melt. The exception is for turbos,
where you need a probe close to the turbo to see what energy is available.
Turbo readings are scary. I don't know how that stuff stays together.
1600 degrees is not unusual on bike engines, though 1450 to 1500 is more
like it for general street bikes (though it's ranging higher as emission
requirements dictate leaner mixtures--one of the reasons that air-cooled
bikes won't be around much longer). The higher the RPM, the hotter the gas
can be, because the valve isn't off the seat for long. Bike engines running
at 15000 RPM commonly have 1700 degree EGT or even higher. Header pipes are
now commonly made of Titanium or even Inconel which handles sustained temps
in excess of 1800 degrees F. On the dyno they glow white hot. They also have
two little exhaust valves per cylinder that get cooled on the seat very
effectively. Absolutely none of this applies to Triumphs, except that most
of this stuff varies according to the engine parameters and there are not
that many absolute rules.
Bill Babcock
Babcock & Jenkins
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of Don Marshall
Sent: Wednesday, May 04, 2005 10:07 AM
To: fot@autox.team.net
Subject: RE: Re: Exhaust Gas Temperature Gage
How far out should the probes be mounted? I've seen 2" and 6", does it
matter and, if so, what is optimal?
BTW, although I didn't get my car back together in time for the Mitty, I did
have a great time watching and visiting with the other FOTers.
Thanks to all who put so much effort into it. Don
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of kaskas@cox.net
Sent: Tuesday, May 03, 2005 8:07 AM
To: Jack W. Drews; WEmery7451@aol.com; fot@autox.team.net
Subject: Re: Re: Exhaust Gas Temperature Gage
You will find that the numbers 2 & 3 are always leaner than the other
cylinders if you are running just a pair of S.U.'s or Strombergs. Were it
me, these are the cylidners I'd have the probe in.
>
> From: "Jack W. Drews" <vinttr4@geneseo.net>
> Date: 2005/05/03 Tue AM 07:01:51 EDT
> To: WEmery7451@aol.com, fot@autox.team.net
> Subject: Re: Exhaust Gas Temperature Gage
>
> Mine also shows no gauge reading at idle. The needles are rather slow
to
> respond and take a few seconds to catch up to what's going on in the
pipes.
> At full song on a long straight several of us see 1400 - 1450. If it's
> running lean, you'll see 1650 but not for very long.
>
> At 12:09 AM 5/3/2005, you wrote:
> >Dear FOT,
> >
> >I finally got around to installing an exhaust gas temperature gage,
with
> >sensors in the Number 1 and Number 4 exhaust manifold pipes. The two
> >scales on
> >the gage range from 8 to 16 degrees F, with a 100 multiplier. At
first, the
> >gage arrows would not move off of their low points, so the gage may
be
> >faulty.
> >Then one of the two arrows started to move upscale, with the other
one not
> >moving at all.
> >
> >This brings on the following questions:
> >
> >-Could there be anything else wrong besides the gage being faulty?
> >
> >-Approximately, what temperatures should I be seeing?
> >
> >-If the gage were working properly, are we supposed to adjust the
mixture to
> >the carburetors to obtain nearly equal temperature readings of the
two
> >needles?
> >
> >I have been adjusting the carburetor jets by turning the nuts out a
specified
> >number of turns, and then using a depth gage to set the jets an equal
> >distance down, with the cover, piston, and needles off of the
carburetor.
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