| Ported Vacuum Switch replacement part [message #237348] |
Fri, 24 January 2014 19:41  |
George B.
Messages: 213
Registered: February 2012
Karma: 1
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Senior Member |
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I can not find a reference for a replacement Ported Vacuum Switch/ Thermal Vacuum Switch for a 73 in the parts interchange index.
GM Parts Book lists two: 413473 - Switch Carburetor thermal vacuum, and 3038957 w/RPO NB4 (Calif emissions)
Any one know a Parts Store equivalent?
Thanks in advance
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
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| Re: Ported Vacuum Switch replacement part [message #237358 is a reply to message #237355] |
Fri, 24 January 2014 21:03  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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It is a useless item. Run the hose from the ported vacuum direct to the distributor and be done with it. The remaining hose can be plugged or eliminated.
If you want you can remove it from the intske manifold and fill the hole with a brass plug or a mechanical temperature gauge sender.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Ported Vacuum Switch replacement part [message #237387 is a reply to message #237348] |
Fri, 24 January 2014 23:18 |
Cadillackeeper
Messages: 464
Registered: October 2012
Location: Fort Lauderdale
Karma: 1
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Senior Member |
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Guys,California has to be totally stock,especially emissions systems.On my Cad I used that hole in the water for the gauge and plugged the gauge hole under the compressor.
I live in florida so its always Hot so even back in the day the wax was out and vacuum
still too much.So it was the first thing to go.I always saved the A.I.R. pumping into the carb though.
77 455 Elaganza II and 67 Animal, Built 500 Powered Eldo
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| Re: [GMCnet] Ported Vacuum Switch replacement part [message #237427 is a reply to message #237356] |
Sat, 25 January 2014 09:56 |
Len Novak
Messages: 676
Registered: February 2004
Location: Las Vegas, NV
Karma: -3
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Senior Member |
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CA smog...........
With both coaches I have owned in CA the tech had no idea what he was
looking at, or for.
I could have had a diesel under the hatch but as long as the air cleaner
said it was a 403, it was a 403.
Cheers,
Len and Pat Novak
1978 GMC Kingsley
The Beast II with dash lights that work and labels you can see!
Fallbrook, CA new email: B52Rule@Roadrunner.Com
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
www.bdub.net/novak/
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of anthony ezzo
Sent: Friday, January 24, 2014 7:00 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Ported Vacuum Switch replacement part
George,You are only minutes from MTS and you have to visit them.You need
the 3 port wax switch.Most disconnect it,but California???
--
77 455 Elaganza II and 67 Animal, Built 500 Powered Eldo
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Len and Pat Novak
1978 GMC Kingsley
The Beast II with dash lights that work and labels you can see!
Las Vegas, NV new email: B52sRule@Gmail.com
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
www.bdub.net/novak/
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| Re: [GMCnet] Ported Vacuum Switch replacement part [message #237431 is a reply to message #237427] |
Sat, 25 January 2014 10:11 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
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Senior Member |
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Forget that &^%$# part, totally unnecessary. It tries to keep the motor lean while it's warming up to reduce emmissions-- it didn't work and only causes problems when it fails which is often! Run a hose from the front of the carb directly to the dist and plug off the rest. You can leave the ported vacuum switch mounted to plug the coolant hole in the intake. This is what we do,
Jim Bounds
----------------------
Jim Bounds
On Saturday, January 25, 2014 10:58 AM, Len Novak <B52Rule@RoadRunner.Com> wrote:
CA smog...........
With both coaches I have owned in CA the tech had no idea what he was
looking at, or for.
I could have had a diesel under the hatch but as long as the air cleaner
said it was a 403, it was a 403.
Cheers,
Len and Pat Novak
1978 GMC Kingsley
The Beast II with dash lights that work and labels you can see!
Fallbrook, CA new email: B52Rule@Roadrunner.Com
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
www.bdub.net/novak/
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of anthony ezzo
Sent: Friday, January 24, 2014 7:00 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Ported Vacuum Switch replacement part
George,You are only minutes from MTS and you have to visit them.You need
the 3 port wax switch.Most disconnect it,but California???
--
77 455 Elaganza II and 67 Animal, Built 500 Powered Eldo
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No virus found in this message.
Checked by AVG - www.avg.com
Version: 2014.0.4259 / Virus Database: 3681/7030 - Release Date: 01/24/14
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| Re: Ported Vacuum Switch replacement part [message #237441 is a reply to message #237348] |
Sat, 25 January 2014 11:48 |
George B.
Messages: 213
Registered: February 2012
Karma: 1
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Senior Member |
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Thanks for the suggestions everyone.
Emery, as typical, you are right...need my glasses just didn't associate with the distributor...till now.
The replacements available seem to be one size fits all and the GM parts book calls for something different for Calif and I think I have a Calif coach. However, I will follow the several recommendations and bypass the vacuum switch. My coach is a 1973 so I do not need an emissions check every two years like 1976+ do.
Only concern is in stop & go traffic and the engine temp goes up is the switch also intended to cause the engine to idle faster thus help with cooling? Or do I have that backwards?
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
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| Re: Ported Vacuum Switch replacement part [message #237442 is a reply to message #237348] |
Sat, 25 January 2014 12:03 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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What the switch really does.... Sends ported (throttle controlled) vac signal to dist vac pot just like a normal hose would in all cases except where the coolant is above the switch point ( about 220?) where it then sends manifold vacuum to the distributor. This vac advance at idle increases idle RPM (more fan and water pump speed) and heat rejection to cool the engine. Rarely comes into play except after a sudden stop or traffic jam after highway speeds on a hot day Then it's nice to have to prevent stalling. No down side I can see if it is working and was used on many GM engines in that 70s era
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Ported Vacuum Switch replacement part [message #237443 is a reply to message #237441] |
Sat, 25 January 2014 14:07 |
jim kanomata
Messages: 257
Registered: March 2007
Location: fremont,ca
Karma: 12
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Senior Member |
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I never delete the part as the real function of this part is to cause the engine RPM to increase when the engine heats up driving around town.
The sensor switches the throttle vacuum to manifold when the engine gets above operating temperature and the vacuum module on the dist. will increase timing, which will increase the engine speed at idle and will help cool the engine.
I noticed that our unit we sell is a Delco unit so we end up paying more, so I will start handling the generic part as they are considerably less money.
International parts exchange need to be updated more, but when Billy Massey request us to help update,were busy with our own projects and can never get it done properly.
I have been insinuated of trying to supply the International parts exchange
list be available to everyone.
I will let you all know that I would not do any such thing.
I might not be to bright, but something like this , I will not.
Those of you that have not signed up for GMC International, should. You will have copy of the interchange and also have the membership list that is very valuable for a mere $30.
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Ported Vacuum Switch replacement part [message #237458 is a reply to message #237431] |
Sat, 25 January 2014 16:03 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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The switch supplies full vacuum to the vacuum advance when the engine gets hot. It serves 2 purposes: the engine idles faster to help cooling and it runs more efficiently to reduce heat build up. Many of us have removed the switch and run full vacuum advance all the time--of course it could fail emissions that way.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: Ported Vacuum Switch replacement part [message #237459 is a reply to message #237439] |
Sat, 25 January 2014 16:04 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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| roy1 wrote on Sat, 25 January 2014 10:11 |
I would just remove it as suggested by others. I had no problem passing smog without it when I lived in Southern California.
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If you remove it and continue to run ported vacuum, it won't have any effect on emissions.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: Ported Vacuum Switch replacement part [message #237460 is a reply to message #237441] |
Sat, 25 January 2014 16:06 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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| George B. wrote on Sat, 25 January 2014 10:48 |
Thanks for the suggestions everyone.
Emery, as typical, you are right...need my glasses just didn't associate with the distributor...till now.
The replacements available seem to be one size fits all and the GM parts book calls for something different for Calif and I think I have a Calif coach. However, I will follow the several recommendations and bypass the vacuum switch. My coach is a 1973 so I do not need an emissions check every two years like 1976+ do.
Only concern is in stop & go traffic and the engine temp goes up is the switch also intended to cause the engine to idle faster thus help with cooling? Or do I have that backwards?
|
You are correct in that when the engine gets hot, the switch goes to full vacuum advance allowing the engine to run cooler.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Ported Vacuum Switch replacement part [message #237468 is a reply to message #237431] |
Sat, 25 January 2014 17:10 |
Nelson Wright
Messages: 147
Registered: May 2004
Karma: 0
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Senior Member |
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Jim,
Remember the dizzy vacuum advance I gave you off my 78 california coach. It had a retard as well as advance port. Why don't you bring this up for discussion?
Nelson
On Jan 25, 2014, at 11:11 AM, Jim Bounds wrote:
> Forget that &^%$# part, totally unnecessary. It tries to keep the motor lean while it's warming up to reduce emmissions-- it didn't work and only causes problems when it fails which is often! Run a hose from the front of the carb directly to the dist and plug off the rest. You can leave the ported vacuum switch mounted to plug the coolant hole in the intake. This is what we do,
>
> Jim Bounds
> ----------------------
>
> Jim Bounds
>
>
>
> On Saturday, January 25, 2014 10:58 AM, Len Novak <B52Rule@RoadRunner.Com> wrote:
>
> CA smog...........
>
> With both coaches I have owned in CA the tech had no idea what he was
> looking at, or for.
>
> I could have had a diesel under the hatch but as long as the air cleaner
> said it was a 403, it was a 403.
>
> Cheers,
>
> Len and Pat Novak
> 1978 GMC Kingsley
> The Beast II with dash lights that work and labels you can see!
> Fallbrook, CA new email: B52Rule@Roadrunner.Com
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
>
> www.bdub.net/novak/
>
>
>
>
> -----Original Message-----
> From: gmclist-bounces@temp.gmcnet.org
> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of anthony ezzo
> Sent: Friday, January 24, 2014 7:00 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Ported Vacuum Switch replacement part
>
>
>
> George,You are only minutes from MTS and you have to visit them.You need
> the 3 port wax switch.Most disconnect it,but California???
> --
> 77 455 Elaganza II and 67 Animal, Built 500 Powered Eldo
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2014.0.4259 / Virus Database: 3681/7030 - Release Date: 01/24/14
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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