| [GMCnet] Vacuum Switch Bypass? [message #78700] |
Wed, 31 March 2010 09:07  |
Ken Coit
Messages: 151
Registered: November 2005
Karma: 0
|
Senior Member |
|
|
If I recall correctly, it was recommended that the vacuum switch be bypassed
and the manifold vacuum be fed directly to the distributor and transmission.
Is that correct?
--
Ken Coit, ND7N
Raleigh, NC
Parfait Royale
1978 Royale Rear Bath, 403, 3.07
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Vacuum Switch Bypass? [message #78701 is a reply to message #78700] |
Wed, 31 March 2010 09:16  |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
|
Senior Member |
|
|
you should get lots of answers on this, here is JWID , just what I do
http://www.gmcmhphotos.com/photos/showphoto.php?photo=3343&cat=3323
*http://tinyurl.com/yc78pxz
*
gene
On Wed, Mar 31, 2010 at 7:07 AM, Ken Coit <ktcoit@gmail.com> wrote:
> If I recall correctly, it was recommended that the vacuum switch be
> bypassed
> and the manifold vacuum be fed directly to the distributor and
> transmission.
> Is that correct?
>
> --
> Ken Coit, ND7N
> Raleigh, NC
> Parfait Royale
> 1978 Royale Rear Bath, 403, 3.07
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Vacuum Switch Bypass? [message #78703 is a reply to message #78700] |
Wed, 31 March 2010 09:32 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
|
Senior Member |
|
|
| Ken Coit wrote on Wed, 31 March 2010 09:07 |
If I recall correctly, it was recommended that the vacuum switch be bypassed
and the manifold vacuum be fed directly to the distributor and transmission.
Is that correct?
--
Ken Coit, ND7N
Raleigh, NC
Parfait Royale
1978 Royale Rear Bath, 403, 3.07
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
Ken,
We have not seen you on the GMCnet for a year. Glad to see you back!
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
|
|
|
|
| Re: [GMCnet] Vacuum Switch Bypass? [message #78709 is a reply to message #78703] |
Wed, 31 March 2010 09:54 |
Ron
Messages: 250
Registered: February 2004
Location: Conifer, Colorado
Karma: 0
|
Senior Member |
|
|
Ken..
Read the charts closely.. You want ported vacuum to the distributor.. Not full vacuum all the time.. When you give it full vacuum at idle it will raise the idle speed creating all sorts of problems..
Ron
now a P.O.
Conifer, CO
|
|
|
|
| Re: [GMCnet] Vacuum Switch Bypass? [message #78725 is a reply to message #78700] |
Wed, 31 March 2010 11:41 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
|
Senior Member |
|
|
| Ken Coit wrote on Wed, 31 March 2010 09:07 |
If I recall correctly, it was recommended that the vacuum switch be bypassed
and the manifold vacuum be fed directly to the distributor and transmission.
Is that correct?
--
Ken Coit, ND7N
Raleigh, NC
Parfait Royale
1978 Royale Rear Bath, 403, 3.07
|
If you want to get rid of the TVS, Remove the manifold vacuum line and from TVS and cap / plug it. Then hook the remaining two hoses together. You are done. No further adjustments required.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
|
|
|
|
| Re: [GMCnet] Vacuum Switch Bypass? [message #78734 is a reply to message #78725] |
Wed, 31 March 2010 12:43 |
Ken Coit
Messages: 151
Registered: November 2005
Karma: 0
|
Senior Member |
|
|
Thanks guys! It is nice to be back and messing with the coach again. We
seem to have a more stable situation here and I can actually find a few
hours a week to make progress even if that dream trip isn't going to happen
the way we planned it.
Ken
On Wed, Mar 31, 2010 at 12:41 PM, Ken Burton <n9cv@comcast.net> wrote:
>
>
> Ken Coit wrote on Wed, 31 March 2010 09:07
> > If I recall correctly, it was recommended that the vacuum switch be
> bypassed
> > and the manifold vacuum be fed directly to the distributor and
> transmission.
> > Is that correct?
> >
> > --
> > Ken Coit, ND7N
> > Raleigh, NC
> > Parfait Royale
> > 1978 Royale Rear Bath, 403, 3.07
>
> If you want to get rid of the TVS, Remove the manifold vacuum line and from
> TVS and cap / plug it. Then hook the remaining two hoses together. You
> are done. No further adjustments required.
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Ken Coit, ND7N
Raleigh, NC
Parfait Royale
1978 Royale Rear Bath, 403, 3.07
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] Vacuum Switch Bypass? [message #78739 is a reply to message #78700] |
Wed, 31 March 2010 13:22 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
|
Senior Member |
|
|
This subject has caused about as much debate as anything except maybe tires. People have gotten offended, arguments have been heated, some have left, and experts have decided to stay quiet to keep out of the fray, all because of where to put a foot's worth of vacuum tubing.
The TVS applies ported vacuum to the distributor, except when the engine is really hot, in which case it applies manifold vacuum to the distributor. In that application, the manifold vacuum raises the idle speed slightly, but it has little other effect. The purpose, as reported here by GM experts who should know, was to reduce advance during idle to improve emissions. The TVS would override that mission when the engine got too hot as a means of self-protection.
Bona fide experts have stated that ported vacuum should be equal to or nearly equal to manifold vacuum at throttle openings and engine speeds other than idle.
There is a myth that ported vacuum is reversed from manifold vacuum; this is not true at all. Experts have told us that all the port does is release the vacuum at idle to reduce vacuum advance.
So, if you use manifold vacuum only and adjust the idle speed accordingly, above idle you should see no difference. The only difference is that at idle, you'll have more advance, which some experts have argued is an advantage.
I'm just explaining what others have explained to me. Do what works for you.
Rick "not an expert, just a reporter" Denney
'73 Glacier 230 "Jaws"
|
|
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
