That was the first thing I thought of when I read the original post but it
sounds different enough to likely be something else. I purchased a new set
of Strombergs a few years ago and immediately noticed the same problem. The
revs took a while longer than usual to drop back to normal. You can plug
the bypass valves but there is an easier way. The valves work by popping
open at a certain vacuum. They will not allow any higher vacuum so the revs
drop slowly while the air is being bypassed. There is a spring that holds
the valve shut and if you open the valve you will see a "nut or bolt" in a
six sided well. You can simply rotate it forward a few turns and the spring
will then hold the valve shut to a higher vacuum. This way the valve still
works and you can choose how fast you want the revs to drop and how much
you want to pollute while decelerating. (count your turns and you will be
able to put it back the way it was easily)
Ed McGuirk
76 TR6
86 Rx7
88 MR2 Supercharged
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Date: Mon, 22 May 2000 12:27:05 -0700 (PDT)
From: Timothy Holbrook <tjh173@yahoo.com>
Subject: Fwd: Re: 74 EGR valve removal/replacement
I ran into a similar problem when installing my triple
stromberg setup a few weeks ago. When I revved the
engine, the revs would drop very, very slowly. I
traced this problem to the air bypass valves on the
carbs. These valves are used to create this condition
(although probably not so exaggerated) on purpose for
emissions reasons. If the revs are allowed to drop
very quickly, it apparently creates a condition that
the emissions legislators don't like. You can read up
on these bypass valves in the fantastic Haynes manual
on Stromberg carbs. Basically, these bypass valves
allow air to bypass the throttle (butterfly) when a
very high amount of manifold pressure exists (as when
the engine is decelarating under no throttle, called
engine braking). This allows air to get to the engine
and keeps the revs from dropping too quickly. What I
did was remove the bypass valves and place a thin
piece of cardboard (about the thickness of a gasket)
between the bypass valve body and the carb body,
blocking off the air passages. These effectively
bypassed the bypass valves, and now the engine drops
back to idle very quickly.
You shouldn't have to do this on a regular spec 6, but
perhaps in fiddling with the vacuum pipes, you have
now created a condition which opens the air bypass
valves. Try bypassing these as I have described, and
maybe that'll fix your problem.
Tim Holbrook
1971 TR6 (with throttle linkage problems being fixed
on the recently installed triple stromberg setup)
> Date: Mon, 15 May 2000 14:16:42 EDT
> From: RedTriumphTr6@aol.com
> Subject: 74 EGR valve removal/replacement
>
> Fellow 6packers: My 74 1/2 seems to have a vacuum
> problem that plagues me
> periodically. I found my idle refusing to drop
> between shifts ...seems to
> stay at about 2200, but then creep back down to 800
> if I wait about five.......
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