Brooks
So as I understand it, you've added a vacuum port to the throat of your SU
to connect to the vacuum retard port on your distributor, ala Mr. Venturi.
Why not just just the vacuum off of the manifold? Don't they track one
another? The guy who sold me this carb set did just that on his '74 TR6.
The other page of Bentley that caught my attention is page 165 in the
section of emission control for TR250 and early TR6. What's the deceleration
control vacuum valve? I have to assume that some of the ZS internal stuff
that came along later replaced this valve, but the real issue is what
happens when you declerate from a high speed. I assume that it should reach
idle speed quickly and that's what this is about.
Boy, I'm out of my league on this one. Any help would be greatly
appreciated.
Jerry Shaw
'74 TR6 CF20490UO Saphire Blue
'66 Spitfire MKII FC70664L BRG
----- Original Message -----
From: "Brooks Bullock" <airsmyth@covad.net>
To: <6pack@autox.team.net>
Sent: Friday, August 03, 2001 9:03 PM
Subject: Re: SU HS6 emissions setup
> Jerry :
>
> I wish I could spread this mailing to everyone but as I understand it, no
> one else would be able to view the pictures that I have scanned from my
> spare carb for a TR4A application
> At the time that I drilled this tapping I did not no where to obtain
the
> Brass tube that we are so accustomed to seeing on the carbs so I used a
#10
> Brass screw that I turned down with a drill and file and press fitted into
> the carb body. As you can see in the file attachment that I have sent
named
> SU Bottom.
> In the picture that I sent named Retard Tapping SU I attempted to
> disclose the tapping through the drilled Hose Nipple(Brass Screw) into the
> throat of the carb body on the Intake side of throttle plate not the air
> Piston side I placed a piece of stainless wire through the hole so that it
> might be more visible.
> One can differentiate between a retard tapping by which side of the
> throttle plate it is positioned,If it is on the air piston side and on the
> top it will drive a vacuum advance unit, if it is on the intake side and
on
> the bottom it will drive a vacuum retard unit.I hope that this clears this
> up on the carb drilling.
> As far as the device you described as an external ZS mechanical
linkage,
> that I believe you are describing the apparatus mounted on the LH side of
> the ZS (as you are looking at them)that is actuated at closed throttle, is
> for the venting of the float bowl either to the air filter region In the
> throttle closed position and to the canister at closed throttle.The only
> valve that I am aware of is the thermo valve located in the radiator hose
> which I have removed. At this time my vacuum circuit looks just like the
> diagram located in the Bentley Manual page 223 (19.15.02C sheet3)bottom RH
> with the exception that I have no EGR valve (plugged the head and
> Intake),plugged the vacuum tapping for the EGR valve(at the top rear
> carb),and omitted that entire vacuum circuit for the EGR.and I have no
more
> petrol trap.
> I called Moss on there conversion they weren't sure that it had a
retard
> tapping or not but did say that they are running a Biased needle(spring
> loaded)with a code I thought I understood to be BHE. I am unable to verify
> the existence of this new cut needle does anyone else know of this needle?
> These are very expensive carbs!!!
> I don't know what everyone else does with there tank vent but I
placed
> a modified fuel filter on it to keep dirt and insects out of my vent
system.
>
> Brooks
> 74 TR6
> Atlanta GA
>
> ----- Original Message -----
> From: "Jerry Shaw" <jcs104@home.com>
> To: <6pack@autox.team.net>
> Sent: Friday, August 03, 2001 7:43 AM
> Subject: Re: SU HS6 emissions setup
>
>
> > Dick and Brooks
> >
> > Thanks for your inputs!
> >
> > This carb set came off of either a TR3 or early TR4, and probably
already
> > has the correct needles.
> >
> > So here's the plan with a couple questions having to do with EGR valves
> and
> > retard behavior.
> >
> > 1) I'm taking off all of the cannister stuff, including the anti-run-on
> > switch and the radiator mounting bracket and putting it away, then
taping
> > the switch connection and rerouting the gas tank hose to a convienient
> > non-vacuum place.
> > 2) I'm going to route the valve cover vent hose through a PCV valve into
> one
> > of two holes in my intake manifold, which is the same manifold as for my
> > ZS's. I assume any PCV valve will suffice (Dick suggested an early TR6
> > version), and I think I need an easy-to-obtain brass fitting to do this,
> or
> > connect it to the cannister vacuum connection.
> > 3) Now here's question #1. Do I remove the EGR valve? It had a
connection
> to
> > the ZS's, as well as into one of the two manifold holes. I can just plug
> the
> > hole in my head (no jokes please), which leads to the exhaust stream,
and
> > plug the intake manifold hole.
> > 4) And here's question #2. Do I just plug up the retard port on the
> > distributor, and how do I compensate for the lack thereof? Brooks, you
> > mentioned #55 hole on the throttle plate? My distributor is the later
> > model with only centrifugal advance, and a retard vacuum diaphram unit.
> > According to Bentley, this connection retards ignition timing during
> > deceleration by opening a valve and applying vacuum to the distributor
> > through a ZS external mechanical linkage and valve. Is it possible to
> devise
> > a similar valve linkage for SUs? The ZS valve is pretty simple.
> >
> > Okay, enough for now.
> >
> > Thanks
> > Jerry Shaw
> > '74 TR6
>
> ----- Original Message -----
> From: "Jerry Shaw" <jcs104@home.com>
> To: <6pack@autox.team.net>
> Sent: Friday, August 03, 2001 7:43 AM
> Subject: Re: SU HS6 emissions setup
>
>
> > Dick and Brooks
> >
> > Thanks for your inputs!
> >
> > This carb set came off of either a TR3 or early TR4, and probably
already
> > has the correct needles.
> >
> > So here's the plan with a couple questions having to do with EGR valves
> and
> > retard behavior.
> >
> > 1) I'm taking off all of the cannister stuff, including the anti-run-on
> > switch and the radiator mounting bracket and putting it away, then
taping
> > the switch connection and rerouting the gas tank hose to a convienient
> > non-vacuum place.
> > 2) I'm going to route the valve cover vent hose through a PCV valve into
> one
> > of two holes in my intake manifold, which is the same manifold as for my
> > ZS's. I assume any PCV valve will suffice (Dick suggested an early TR6
> > version), and I think I need an easy-to-obtain brass fitting to do this,
> or
> > connect it to the cannister vacuum connection.
> > 3) Now here's question #1. Do I remove the EGR valve? It had a
connection
> to
> > the ZS's, as well as into one of the two manifold holes. I can just plug
> the
> > hole in my head (no jokes please), which leads to the exhaust stream,
and
> > plug the intake manifold hole.
> > 4) And here's question #2. Do I just plug up the retard port on the
> > distributor, and how do I compensate for the lack thereof? Brooks, you
> > mentioned #55 hole on the throttle plate? My distributor is the later
> > model with only centrifugal advance, and a retard vacuum diaphram unit.
> > According to Bentley, this connection retards ignition timing during
> > deceleration by opening a valve and applying vacuum to the distributor
> > through a ZS external mechanical linkage and valve. Is it possible to
> devise
> > a similar valve linkage for SUs? The ZS valve is pretty simple.
> >
> > Okay, enough for now.
> >
> > Thanks
> > Jerry Shaw
> > '74 TR6
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