Removing FI-Tech

Think of it this way. What does the absence of vacuum do to the
distributor? It allows the spring pushing against the vacuum diaphram to
move the movable pole piece inside the distributor so that the pole pieces
align later in the rotation of the distributor shaft. Result? It retards
the ignition timing.
What does the presence of vacuum do to the distributor? It overrides
the spring pressure, and allows the pole pieces to align earlier in the
rotation, and advances the spark timing.
Jim Hupy
Salem, Oregon

On Sun, Nov 10, 2019, 12:47 PM Matt Colie via Gmclist <

> > Ok I have most of the carb connections back in place but I need to
> reconnect the vacuum advance to the distributor.
> > The vacuum Christmas tree is no longer there and was replaced by the
> temp sensor for the FI-Tech.
> > Since 99% of the time the Christmas tree directs ported vacuum to the
> distributor which of the two connectors on the front of the carb did the
> > Christmas tree connect to.
> > My other question is what are the two vacuum ports on the front of the
> Carb for?
> >
> > Picture of the front of the carb here
> > http://www.gmcmhphotos.com/photos/misc/p66819-carb-ports-sm.html
>
> Tom,
>
> I'm not going to be much help. I have used both ported and manifold. I
> think it is manifold today. If you do go to the manifold, you may have to
> back down the idle air a bunch.
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Try this:

http://www.gmcmhphotos.com/photos/tvs-and-vacuum/p3341.html

On Sun, Nov 10, 2019 at 2:45 PM James Hupy via Gmclist <

> Think of it this way. What does the absence of vacuum do to the
> distributor? It allows the spring pushing against the vacuum diaphram to
> move the movable pole piece inside the distributor so that the pole pieces
> align later in the rotation of the distributor shaft. Result? It retards
> the ignition timing.
> What does the presence of vacuum do to the distributor? It overrides
> the spring pressure, and allows the pole pieces to align earlier in the
> rotation, and advances the spark timing.
> Jim Hupy
> Salem, Oregon
>
> On Sun, Nov 10, 2019, 12:47 PM Matt Colie via Gmclist <

>

> > > Ok I have most of the carb connections back in place but I need to
> > reconnect the vacuum advance to the distributor.
> > > The vacuum Christmas tree is no longer there and was replaced by the
> > temp sensor for the FI-Tech.
> > > Since 99% of the time the Christmas tree directs ported vacuum to the
> > distributor which of the two connectors on the front of the carb did the
> > > Christmas tree connect to.
> > > My other question is what are the two vacuum ports on the front of the
> > Carb for?
> > >
> > > Picture of the front of the carb here
> > > http://www.gmcmhphotos.com/photos/misc/p66819-carb-ports-sm.html
> >
> > Tom,
> >
> > I'm not going to be much help. I have used both ported and manifold. I
> > think it is manifold today. If you do go to the manifold, you may have
> to
> > back down the idle air a bunch.
> >
> > Matt
> > --
> > Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> > Electronically Controlled Quiet Engine Cooling Fan
> > OE Rear Drum Brakes with Applied Control Arms
> > SE Michigan - Twixt A2 and Detroit
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
 
You can run on ported or on none ported vacumm ....it just depends on camshaft profile, idle rpm and to some degree the torque converter. I would
think in our application having a functional vacuum advance would be good but i bet most would never notice if the distributor fly weights were seized
in.
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
> Try this:
>
> http://www.gmcmhphotos.com/photos/tvs-and-vacuum/p3341.html
>
> On Sun, Nov 10, 2019 at 2:45 PM James Hupy via Gmclist <

>
> > Think of it this way. What does the absence of vacuum do to the
> > distributor? It allows the spring pushing against the vacuum diaphram to
> > move the movable pole piece inside the distributor so that the pole pieces
> > align later in the rotation of the distributor shaft. Result? It retards
> > the ignition timing.
> > What does the presence of vacuum do to the distributor? It overrides
> > the spring pressure, and allows the pole pieces to align earlier in the
> > rotation, and advances the spark timing.
> > Jim Hupy
> > Salem, Oregon
> >

> >

> >>> Ok I have most of the carb connections back in place but I need to
> >> reconnect the vacuum advance to the distributor.
> >>> The vacuum Christmas tree is no longer there and was replaced by the
> >> temp sensor for the FI-Tech.
> >>> Since 99% of the time the Christmas tree directs ported vacuum to the
> >> distributor which of the two connectors on the front of the carb did the
> >>> Christmas tree connect to.
> >>> My other question is what are the two vacuum ports on the front of the
> >> Carb for?
> >>>
> >>> Picture of the front of the carb here
> >>> http://www.gmcmhphotos.com/photos/misc/p66819-carb-ports-sm.html
> >>
> >> Tom,
> >>
> >> I'm not going to be much help. I have used both ported and manifold. I
> >> think it is manifold today. If you do go to the manifold, you may have
> > to
> >> back down the idle air a bunch.
> >>
> >> Matt
> >> --
> >> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> >> Electronically Controlled Quiet Engine Cooling Fan
> >> OE Rear Drum Brakes with Applied Control Arms
> >> SE Michigan - Twixt A2 and Detroit
> >>
> >> _______________________________________________
> >> GMCnet mailing list
> >> Unsubscribe or Change List Options:
> >> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >>
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
>
>
> --
> Bruce Hart
> 1976 Palm Beach
> Milliken, Co
> GMC=Got More Class
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Thanks Bruce
I saw that one and it is a little unclear.

Dick Springfield sent me a very good diagram
Thanks to everyone.

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
 
The diagram is pretty simple once understood. The TVS is a simple A or B vacuum switch that changes over at about 220F. So it sends ported vacuum to
the distributor about 99% of the time In the event of an overheat it flips to manifold vacuum This advances timing at idle to increase speed and
improve heat rejection.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Tom,
Can you pass on the diagram from Springfield.

On Sun, Nov 10, 2019 at 5:53 PM John R. Lebetski via Gmclist <

> The diagram is pretty simple once understood. The TVS is a simple A or B
> vacuum switch that changes over at about 220F. So it sends ported vacuum to
> the distributor about 99% of the time In the event of an overheat it
> flips to manifold vacuum This advances timing at idle to increase speed
> and
> improve heat rejection.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
 
The port you want is on the diver's side front of the carb. The picture you saw previously posted is unclear because the port shown in the picture
for manifold vacuum is NOT in the carb. It really is a 90 degree fitting mounted in the ibntake manifold.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> Tom,
> Can you pass on the diagram from Springfield.
>
>
>
> --
> Bruce Hart
> 1976 Palm Beach
> Milliken, Co
> GMC=Got More Class
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

The big difference with Dick's diagram is he added the small drawing of the front of the Carb, which is absolutely what I needed
Bob Burkett also sent me a close-up of the front of the Carb with labels on the picture and some more diagrams which were also very helpful.

Got it running today, now I just have to get the snorkel to remote air filter to seal tight on the top of the Carb.

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
 
Should be able to use a stock air cleaner meant for a HEI equipped engine.
Jim Hupy
Salem, Oregon

On Mon, Nov 11, 2019, 6:36 PM Tom Lins via Gmclist
wrote:

> > Tom,
> > Can you pass on the diagram from Springfield.
> >
> >
> >
> > --
> > Bruce Hart
> > 1976 Palm Beach
> > Milliken, Co
> > GMC=Got More Class
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> The big difference with Dick's diagram is he added the small drawing of
> the front of the Carb, which is absolutely what I needed
> Bob Burkett also sent me a close-up of the front of the Carb with labels
> on the picture and some more diagrams which were also very helpful.
>
> Got it running today, now I just have to get the snorkel to remote air
> filter to seal tight on the top of the Carb.
>
> --
> Tom Lins
> St Augustine, FL
> 77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI, Aluminum Radiator Quad-Bag
> Suspension Solar Panel
> Manuals on DVD
> GMC Dealer Training Tapes
> http://www.bdub.net/tomlins/
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> Hi Tom
> Thanks for sharing the diagram.
>
> FYI, I went in and edited the titles so that it can be found by a search.
> Spelled out rather than abbreviated.
>
> Thanks again
> bdub
>
>
> -----Original Message-----
> From: Gmclist On Behalf Of Tom Lins via Gmclist
> Sent: Tuesday, November 12, 2019 7:41 AM
> Subject: Re: [GMCnet] Removing FI-Tech
>
> http://www.gmcmhphotos.com/photos/misc/p66820-vac-hose-connections-sm.html
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Bdub
Thanks for adding that.

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
 
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