Jim, I simply bought an early TR6 dizzy on ebay. These have both vacuum
advance and retard but I removed the retard unit and replaced it with
the standard Lucas vernier wheel. I send the thing off to Bob Sarama
(sorry if I have mangled his name) and it came back looking and
performing like new. Around that time I bought some refurbed carbs from
Jeff Palya and after discussing with him what my plans were he sent me a
manifold and carbs that were equipped with the vacuum advance port and
with the retard port closed off. These carbs also arrived looking and
performing like new. This combination totally transformed the car, it
was like night and day and I'm sure a lot of that was just from having
correctly functioning carbs and dizzy but I hope some of the improvement
is attributable to the better advance curve from the vacuum + mechanical
plus the tweaks that Bob made to the innards to give me the correct
advance curve.
Sorry for the name dropping, I don't know these guys other than as a
happy customer.
Stan
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of James Juhas
Sent: Wednesday, September 13, 2006 5:45 PM
To: Sally or Dick Taylor
Cc: TR6 List
Subject: Re: Vacuum Retard
Dick (and Stan):
Thanks. I can't test in place because of where my vacuum supply is.
I'm checking with a vacuum pump, and it appears to leak. In any event,
I can't use a retard mechanism anyway with the SU setup. I'd love to
acquire a vacuum advance distributor or get to full advance solely on
the mechanical advance. Perhaps my Bently manual will tell me what
advance should be at various RPM?
Jim
Sally or Dick Taylor wrote:
>James--- If your vacuum supply is constant and the timing won't stay
>retarded, (14 deg. would be about right) then the retard capsule may be
>leaking. Tee in a vacuum gauge to the test line to see if you are
>getting enough vacuum to pull the points plate CCW. Standard manifold
>vacuum of 20 inches would be plenty, but even 10 inches should work.
>
>A properly working ignition retard at idle, has little effect on
>performance, since the retard is canceled as soon as you dip into the
>throttle. It is there for emission pruposes. (NOx reduction)
>
>You are correct in that the ports on the SU is not there for vacuum
>retard, but rather for vacuum advance. The port for vacuum retard on
the
>1973 model ZS is under the bottom of the rear carburetor.
>
>Dick
>
>From:
>james.f.juhas@snet.net(James Juhas)
>
>I'm trying to tell whether the vacuum retard unit on my 1973 TR6
>distributor is working properly. When I apply a vacuum to it, it moves
>but does not hold the vacuum, so returns to its resting position. It's
>as if a sudden vacuum signal would move it, but then it drops back.
>Should it behave this way, or is it simply leaking?
>A supplementary question is: does this engine really need this feature
>for performance reasons,
>
>or is the vacuum retard only an accommodation to emissions control?
>
>I am converting this car from downdraft webers to SUs and this provides
>me with a vacuum signal at the carb which, I believe, will be present
at
>partial and full throttle, and this seems wrong to me to connect this
to
>a retard unit. In the normal Stomberg setup, where does the retard
>vacuum unit port attach?
>Thanks.
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