Doug:
My 74-1/2 has the same 4 port vacuum switch. It was missing when
I bought
the car, and I picked one up at a swap meet. Unfortunately, I don't know
if it
is correct for my year. I studied my Moss catalog, and the TRF drawings.
Still don't know.
Anyhooo... I checked a '76 that was highly original, and it had
the
lines arranged a little differently. On the 76, the lines were connected
such that if I use your picture as an example, the dust cap and the
green
vacuum line would be swapped. I am not sure you could trust that as an
example,
however, since who knows if it is correct? I went ahead and hooked mine
up
using the 76 as an example, and it seems to work. But does it work
properly?
As for the existence of the 4th port, it is likely correct for
at least
some years, IMHO. Most of the British Leyland emissions stuff was GM
designs
made under license. Those designs were evolving as the laws changed, so
the
designs were changing to accommodate more and more valves, sensors, etc.
It
seems reasonable that later cars would have had the 4 port switch
substituted
when the 3 port was dropped (no longer sufficient). Witness the 2 port
vs. 3 port
carbon canister; The 2 port is no longer available new, so you
substitute the
3 port and cap off the extra port for earlier cars.
Only the LBC god (little 'g') Lucas knows for sure...
Vance
------------------------------
1974 Mimosa Yellow Triumph TR6
Cogito Ergo Zoom
(I think, therefore I go fast)
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Douglas Morris
Sent: Thursday, February 26, 2004 6:42 PM
To: 6pack
Subject: Speaking of Vacuum Lines
Hokay... my '74 has three vac lines attached to the thermostatic valve
in
the upper radiator hose.
That's two to the carbs and one to the distributor's vac retard capsule.
The switch has a fourth port , though.
I blocked this fourth one with a rubber brake bleed-screw dust cap.
<http://mediaservice.photoisland.com/auction/Feb/20042263154176674610027
.jpg
>
I haven't found any drawing which shows four ports.
I haven't found any book which even discusses the thermostatic valve.
So... what's the fourth vac port for?
How does the thermostatic valve work?
Does it matter which vac tube is connected to which port?
Doug Morris '74 TR6 CF18kUO, NC
(just got it back on the road yesterday... today, four inches of snow)
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