Changing the weight of the oil in the dashpots will not change the overall
tuning of the engine (rich - lean).
The piston damper serves the function of the accelerator pump in a
conventional carb. The carbs are constant depression, meaning the vacuum
created across the bridge at the jet is constant. Therefore the vacuum
sucking gas through the jet is constant. The vacuum is maintained constant
by the piston rising or falling, enlarging or constricting the opening in
accord with the volume of air to maintain constant vacuum.
By dampening the rise of the piston, under hard acceleration, the rise of
the piston is slowed, so the hole the air must pass through is smaller, so
the velocity is increased and hence there is more vacuum across the bridge
and more vacuum means more gas is sucked through the jet. Thus, the mixture
is enriched during the interval the piston rise is slowed, but once the
system reaches equilibrium and the piston is at its destination height the
oil does nothing.
Nor does it anything during deceleration, note that it falls freely in spite
of the oil. Its only during acceleration the oil does anything at all.
I agree that the car runs like crap without oil in the dash pots, but it'll
idle and cruise fine, so long as you don't accelerate. Going to a thicker
oil will result in richer mixture during acceleration as the rise of the
piston will be more better slowed and thinner oil will result in a leaner
mixture during acceleration as it will restrain the piston rise less.
I disclaim complete technical accuracy in this discussion, but the basic
principle is correct to my understanding.
Jim Altman jaltman@altlaw.com Illigitimi non Carborundum
http://www.altlaw.com/metro/jaltman.html 69-TR6#CC28754L W4UCK
-----Original Message-----
From: owner-triumphs@autox.team.net
[mailto:owner-triumphs@autox.team.net]On Behalf Of John Herlig
Sent: Tuesday, July 27, 1999 2:24 PM
To: triumphs@autox.team.net
Subject: Running rich -- dashpot oil?
Hello listers!
As the flag bearer in the "Got All the Passion but Can't Fix Diddly"
parade, I have noticed three things telling me that my 59 TR3A is
running rather rich: (1) Black smoke, (2) Odor, and (3) Comments from
my wife (see #2).
I think, in my ignorance, that I have the carbs leaned pretty far down.
No fix there. I have been following the dashpot oil thread of late, and
I wonder if a switch to a thinner oil would be a logical experiment?
Thanks in advance for your help.
John Herlig
Stafford, Virginia
(I live here to make Fred's car look EVEN BETTER, if possible)
1959 TR3A
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