Home » Public Forums » GMCnet » [GMCnet] trnsmission troubles
| [GMCnet] trnsmission troubles [message #242654] |
Fri, 07 March 2014 16:43  |
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Marc Hogenboom[2]
Messages: 70
Registered: March 2011
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Hi All, getting ready for our trip to Montgomery I just ran into a tranny problem.
After getting from my property to the blacktop (15 min in 1st gear)the tranny works well for about 6 or 7 miles, than starts shifting back to 2nd. It wont stay in 3rd.
It will shift up to 3rd but than shifts back.
Vacuum on the modulator is about 10 inches.
Could this be caused by the governor?
Could it be the vacuum regulator that translates throttle position into required vacuum? (diesel, so no engine vacuum)
Marc Hogenboom
‘73 Painted Desert Diesel
Madrid, NM
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| Re: [GMCnet] trnsmission troubles [message #242660 is a reply to message #242654] |
Fri, 07 March 2014 17:37  |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
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Marc
It's in 3rd and shifts down into 2nd.....then it shift back up into 3rd
after a few miles?? Then down into 2nd again...and it repeats ...
Is this correct?
Mike in NS
On Fri, Mar 7, 2014 at 6:43 PM, Marc Hogenboom
<marc.hogenboom@hotmail.com>wrote:
> Hi All, getting ready for our trip to Montgomery I just ran into a tranny
> problem.
> After getting from my property to the blacktop (15 min in 1st gear)the
> tranny works well for about 6 or 7 miles, than starts shifting back to 2nd.
> It wont stay in 3rd.
> It will shift up to 3rd but than shifts back.
> Vacuum on the modulator is about 10 inches.
> Could this be caused by the governor?
> Could it be the vacuum regulator that translates throttle position into
> required vacuum? (diesel, so no engine vacuum)
>
> Marc Hogenboom
> '73 Painted Desert Diesel
> Madrid, NM
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
* At my age, getting lucky means walking into a room and remembering what I
came for.
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| Re: [GMCnet] trnsmission troubles [message #242664 is a reply to message #242659] |
Fri, 07 March 2014 17:41 |
scott cowden
Messages: 170
Registered: February 2004
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I was thinking the same as emery, but wondered how it's controlled with the vacuumless diesel.
Scott
Sent from my iPhone
> On Mar 7, 2014, at 6:34 PM, "Emery Stora" <emerystora@mac.com> wrote:
>
> Marc
>
> It sounds like the modulator rather than the governor. Have you checked the vacuum line to the modulator for leaks? Also check the modulator to see if it holds a vacuum ( if it doesn't that would mean a diaphragm leak.
>
> You might temry replacing the modulator to see if that corrects the problem.
>
> Emery Stora
>
>> On Mar 7, 2014, at 3:43 PM, Marc Hogenboom <marc.hogenboom@hotmail.com> wrote:
>>
>> Hi All, getting ready for our trip to Montgomery I just ran into a tranny problem.
>> After getting from my property to the blacktop (15 min in 1st gear)the tranny works well for about 6 or 7 miles, than starts shifting back to 2nd. It wont stay in 3rd.
>> It will shift up to 3rd but than shifts back.
>> Vacuum on the modulator is about 10 inches.
>> Could this be caused by the governor?
>> Could it be the vacuum regulator that translates throttle position into required vacuum? (diesel, so no engine vacuum)
>>
>> Marc Hogenboom
>> ‘73 Painted Desert Diesel
>> Madrid, NM
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
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| Re: [GMCnet] trnsmission troubles [message #242667 is a reply to message #242666] |
Fri, 07 March 2014 17:44 |
scott cowden
Messages: 170
Registered: February 2004
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As I recall, what you describe as a symptom sounds like what happens if the vacuum line gets disconnected.
Sent from my iPhone
> On Mar 7, 2014, at 6:43 PM, "scott cowden" <scottyforsail@hotmail.com> wrote:
>
> Marc;
>
> How does the diesel send vacuum signal to the modulator?
>
> Sent from my iPhone
>
>> On Mar 7, 2014, at 6:42 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com> wrote:
>>
>> Emery, the vacuum modulator holds a vacuum, I checked the vacuum at the
>> modulator and it is about 10 inches.
>>
>> -----Oorspronkelijk bericht-----
>> From: Emery Stora
>> Sent: Friday, March 07, 2014 4:33 PM
>> To: gmclist@temp.gmcnet.org
>> Subject: Re: [GMCnet] trnsmission troubles
>>
>> Marc
>>
>> It sounds like the modulator rather than the governor. Have you checked the
>> vacuum line to the modulator for leaks? Also check the modulator to see if
>> it holds a vacuum ( if it doesn't that would mean a diaphragm leak.
>>
>> You might temry replacing the modulator to see if that corrects the problem.
>>
>> Emery Stora
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
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| Re: [GMCnet] trnsmission troubles [message #242668 is a reply to message #242660] |
Fri, 07 March 2014 17:44 |
Marc Hogenboom[2]
Messages: 70
Registered: March 2011
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No, it shifts up to 3rd, than down. When I slowly decrease throttle it
shifts up again, but as soon as I increase throttle it shifts down.
-----Oorspronkelijk bericht-----
From: Kingsley Coach
Sent: Friday, March 07, 2014 4:37 PM
To: Gmclist
Subject: Re: [GMCnet] trnsmission troubles
Marc
It's in 3rd and shifts down into 2nd.....then it shift back up into 3rd
after a few miles?? Then down into 2nd again...and it repeats ...
Is this correct?
Mike in NS
On Fri, Mar 7, 2014 at 6:43 PM, Marc Hogenboom
<marc.hogenboom@hotmail.com>wrote:
> Hi All, getting ready for our trip to Montgomery I just ran into a tranny
> problem.
> After getting from my property to the blacktop (15 min in 1st gear)the
> tranny works well for about 6 or 7 miles, than starts shifting back to
> 2nd.
> It wont stay in 3rd.
> It will shift up to 3rd but than shifts back.
> Vacuum on the modulator is about 10 inches.
> Could this be caused by the governor?
> Could it be the vacuum regulator that translates throttle position into
> required vacuum? (diesel, so no engine vacuum)
>
> Marc Hogenboom
> '73 Painted Desert Diesel
> Madrid, NM
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
* At my age, getting lucky means walking into a room and remembering what I
came for.
_______________________________________________
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Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] trnsmission troubles [message #242669 is a reply to message #242666] |
Fri, 07 March 2014 17:47 |
Marc Hogenboom[2]
Messages: 70
Registered: March 2011
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Scott, the vacuum is regulated with a regulator al the throttle shaft. Line
in full vacuum, line out modulated vacuum
Marc
-----Oorspronkelijk bericht-----
From: scott cowden
Sent: Friday, March 07, 2014 4:43 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] trnsmission troubles
Marc;
How does the diesel send vacuum signal to the modulator?
Sent from my iPhone
> On Mar 7, 2014, at 6:42 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com>
> wrote:
>
> Emery, the vacuum modulator holds a vacuum, I checked the vacuum at the
> modulator and it is about 10 inches.
>
> -----Oorspronkelijk bericht-----
> From: Emery Stora
> Sent: Friday, March 07, 2014 4:33 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] trnsmission troubles
>
> Marc
>
> It sounds like the modulator rather than the governor. Have you checked
> the
> vacuum line to the modulator for leaks? Also check the modulator to see
> if
> it holds a vacuum ( if it doesn't that would mean a diaphragm leak.
>
> You might temry replacing the modulator to see if that corrects the
> problem.
>
> Emery Stora
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] trnsmission troubles [message #242671 is a reply to message #242669] |
Fri, 07 March 2014 17:50 |
scott cowden
Messages: 170
Registered: February 2004
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Ok. So, assuming that a vacuum pump is in play here, is the pump putting out vacuum, and is that vacuum making it through the controller to the modulator?
Sent from my iPhone
> On Mar 7, 2014, at 6:47 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com> wrote:
>
> Scott, the vacuum is regulated with a regulator al the throttle shaft. Line
> in full vacuum, line out modulated vacuum
>
> Marc
>
> -----Oorspronkelijk bericht-----
> From: scott cowden
> Sent: Friday, March 07, 2014 4:43 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] trnsmission troubles
>
> Marc;
>
> How does the diesel send vacuum signal to the modulator?
>
> Sent from my iPhone
>
>> On Mar 7, 2014, at 6:42 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com>
>> wrote:
>>
>> Emery, the vacuum modulator holds a vacuum, I checked the vacuum at the
>> modulator and it is about 10 inches.
>>
>> -----Oorspronkelijk bericht-----
>> From: Emery Stora
>> Sent: Friday, March 07, 2014 4:33 PM
>> To: gmclist@temp.gmcnet.org
>> Subject: Re: [GMCnet] trnsmission troubles
>>
>> Marc
>>
>> It sounds like the modulator rather than the governor. Have you checked
>> the
>> vacuum line to the modulator for leaks? Also check the modulator to see
>> if
>> it holds a vacuum ( if it doesn't that would mean a diaphragm leak.
>>
>> You might temry replacing the modulator to see if that corrects the
>> problem.
>>
>> Emery Stora
>>
>> _______________________________________________
>> 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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| Re: [GMCnet] trnsmission troubles [message #242679 is a reply to message #242671] |
Fri, 07 March 2014 18:24 |
Marc Hogenboom[2]
Messages: 70
Registered: March 2011
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Off course, there is a camshaft driven vacuum pump, it's working and the
vacuum (10 inches) reaches the modulator . At least on idle.
I'll have to take it out and play with it, engine running, and see what
happens. Problem is, the troubles start only after about 6 miles, so
probably heat is a factor too!
Marc
-----Oorspronkelijk bericht-----
From: scott cowden
Sent: Friday, March 07, 2014 4:50 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] trnsmission troubles
Ok. So, assuming that a vacuum pump is in play here, is the pump putting out
vacuum, and is that vacuum making it through the controller to the
modulator?
Sent from my iPhone
> On Mar 7, 2014, at 6:47 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com>
> wrote:
>
> Scott, the vacuum is regulated with a regulator al the throttle shaft.
> Line
> in full vacuum, line out modulated vacuum
>
> Marc
>
> -----Oorspronkelijk bericht-----
> From: scott cowden
> Sent: Friday, March 07, 2014 4:43 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] trnsmission troubles
>
> Marc;
>
> How does the diesel send vacuum signal to the modulator?
>
> Sent from my iPhone
>
>> On Mar 7, 2014, at 6:42 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com>
>> wrote:
>>
>> Emery, the vacuum modulator holds a vacuum, I checked the vacuum at the
>> modulator and it is about 10 inches.
>>
>> -----Oorspronkelijk bericht-----
>> From: Emery Stora
>> Sent: Friday, March 07, 2014 4:33 PM
>> To: gmclist@temp.gmcnet.org
>> Subject: Re: [GMCnet] trnsmission troubles
>>
>> Marc
>>
>> It sounds like the modulator rather than the governor. Have you checked
>> the
>> vacuum line to the modulator for leaks? Also check the modulator to see
>> if
>> it holds a vacuum ( if it doesn't that would mean a diaphragm leak.
>>
>> You might temry replacing the modulator to see if that corrects the
>> problem.
>>
>> Emery Stora
>>
>> _______________________________________________
>> 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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| Re: [GMCnet] trnsmission troubles [message #242680 is a reply to message #242679] |
Fri, 07 March 2014 18:29 |
scott cowden
Messages: 170
Registered: February 2004
Karma: 0
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Senior Member |
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yeah, the 6 mile thing does add a twist to it all.
the kickdown switch idea was interesting, too.
Suggest checking the vacuum lines to see if one is damaged/pinched and is changing as the engine/trans heat up.
Have seen quite a few rubber lines with cracked/damaged sections where it's exposed to high heat. can cause intermittent performance.
Good luck.
Scott
> From: marc.hogenboom@hotmail.com
> To: gmclist@temp.gmcnet.org
> Date: Fri, 7 Mar 2014 17:24:04 -0700
> Subject: Re: [GMCnet] trnsmission troubles
>
> Off course, there is a camshaft driven vacuum pump, it's working and the
> vacuum (10 inches) reaches the modulator . At least on idle.
> I'll have to take it out and play with it, engine running, and see what
> happens. Problem is, the troubles start only after about 6 miles, so
> probably heat is a factor too!
>
> Marc
>
> -----Oorspronkelijk bericht-----
> From: scott cowden
> Sent: Friday, March 07, 2014 4:50 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] trnsmission troubles
>
> Ok. So, assuming that a vacuum pump is in play here, is the pump putting out
> vacuum, and is that vacuum making it through the controller to the
> modulator?
>
> Sent from my iPhone
>
> > On Mar 7, 2014, at 6:47 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com>
> > wrote:
> >
> > Scott, the vacuum is regulated with a regulator al the throttle shaft.
> > Line
> > in full vacuum, line out modulated vacuum
> >
> > Marc
> >
> > -----Oorspronkelijk bericht-----
> > From: scott cowden
> > Sent: Friday, March 07, 2014 4:43 PM
> > To: gmclist@temp.gmcnet.org
> > Subject: Re: [GMCnet] trnsmission troubles
> >
> > Marc;
> >
> > How does the diesel send vacuum signal to the modulator?
> >
> > Sent from my iPhone
> >
> >> On Mar 7, 2014, at 6:42 PM, "Marc Hogenboom" <marc.hogenboom@hotmail.com>
> >> wrote:
> >>
> >> Emery, the vacuum modulator holds a vacuum, I checked the vacuum at the
> >> modulator and it is about 10 inches.
> >>
> >> -----Oorspronkelijk bericht-----
> >> From: Emery Stora
> >> Sent: Friday, March 07, 2014 4:33 PM
> >> To: gmclist@temp.gmcnet.org
> >> Subject: Re: [GMCnet] trnsmission troubles
> >>
> >> Marc
> >>
> >> It sounds like the modulator rather than the governor. Have you checked
> >> the
> >> vacuum line to the modulator for leaks? Also check the modulator to see
> >> if
> >> it holds a vacuum ( if it doesn't that would mean a diaphragm leak.
> >>
> >> You might temry replacing the modulator to see if that corrects the
> >> problem.
> >>
> >> Emery Stora
> >>
> >> _______________________________________________
> >> 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
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
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>
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| Re: [GMCnet] trnsmission troubles [message #242683 is a reply to message #242680] |
Fri, 07 March 2014 18:34 |
Marc Hogenboom[2]
Messages: 70
Registered: March 2011
Karma: 0
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I'll have to check those again!( 3rd or 4th time)
Marc
-----Oorspronkelijk bericht-----
From: scott cowden
Sent: Friday, March 07, 2014 5:29 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] trnsmission troubles
yeah, the 6 mile thing does add a twist to it all.
the kickdown switch idea was interesting, too.
Suggest checking the vacuum lines to see if one is damaged/pinched and is
changing as the engine/trans heat up.
Have seen quite a few rubber lines with cracked/damaged sections where it's
exposed to high heat. can cause intermittent performance.
Good luck.
Scott
> From: marc.hogenboom@hotmail.com
> To: gmclist@temp.gmcnet.org
> Date: Fri, 7 Mar 2014 17:24:04 -0700
> Subject: Re: [GMCnet] trnsmission troubles
>
> Off course, there is a camshaft driven vacuum pump, it's working and the
> vacuum (10 inches) reaches the modulator . At least on idle.
> I'll have to take it out and play with it, engine running, and see what
> happens. Problem is, the troubles start only after about 6 miles, so
> probably heat is a factor too!
>
> Marc
>
> -----Oorspronkelijk bericht-----
> From: scott cowden
> Sent: Friday, March 07, 2014 4:50 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] trnsmission troubles
>
> Ok. So, assuming that a vacuum pump is in play here, is the pump putting
> out
> vacuum, and is that vacuum making it through the controller to the
> modulator?
>
> Sent from my iPhone
>
> > On Mar 7, 2014, at 6:47 PM, "Marc Hogenboom"
> > <marc.hogenboom@hotmail.com>
> > wrote:
> >
> > Scott, the vacuum is regulated with a regulator al the throttle shaft.
> > Line
> > in full vacuum, line out modulated vacuum
> >
> > Marc
> >
> > -----Oorspronkelijk bericht-----
> > From: scott cowden
> > Sent: Friday, March 07, 2014 4:43 PM
> > To: gmclist@temp.gmcnet.org
> > Subject: Re: [GMCnet] trnsmission troubles
> >
> > Marc;
> >
> > How does the diesel send vacuum signal to the modulator?
> >
> > Sent from my iPhone
> >
> >> On Mar 7, 2014, at 6:42 PM, "Marc Hogenboom"
> >> <marc.hogenboom@hotmail.com>
> >> wrote:
> >>
> >> Emery, the vacuum modulator holds a vacuum, I checked the vacuum at the
> >> modulator and it is about 10 inches.
> >>
> >> -----Oorspronkelijk bericht-----
> >> From: Emery Stora
> >> Sent: Friday, March 07, 2014 4:33 PM
> >> To: gmclist@temp.gmcnet.org
> >> Subject: Re: [GMCnet] trnsmission troubles
> >>
> >> Marc
> >>
> >> It sounds like the modulator rather than the governor. Have you checked
> >> the
> >> vacuum line to the modulator for leaks? Also check the modulator to
> >> see
> >> if
> >> it holds a vacuum ( if it doesn't that would mean a diaphragm leak.
> >>
> >> You might temry replacing the modulator to see if that corrects the
> >> problem.
> >>
> >> Emery Stora
> >>
> >> _______________________________________________
> >> 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
> >
> > _______________________________________________
> > 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:
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>
> _______________________________________________
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| Re: [GMCnet] trnsmission troubles [message #242689 is a reply to message #242654] |
Fri, 07 March 2014 19:58 |
cbryan
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
|
Senior Member |
|
|
Marc Hogenboom[2] wrote on Fri, 07 March 2014 16:43]Hi All, getting ready for our trip to Montgomery I just ran into a tranny problem.
After getting from my property to the blacktop (15 min in 1st gear)the tranny works well for about 6 or 7 miles, than starts shifting back to 2nd. It wont stay in 3rd.
It will shift up to 3rd but than shifts back.
Vacuum on the modulator is about 10 inches.....end quote.
Marc,
Hot rodders who run lumpy cams with low engine vacuum use a "black and red stripe" modulator as opposed to a "red stripe" modulator. Black and red pulls in at 14 - 15 psi, while the stock red pulls in at 18-20. These stripes on the housing identify which one you are running. With your setup having only 10 psi, I think maybe look at your vacuum pump. Is there a filter involved? We gasoline people always have manifold vacuum and don't properly "appreciate" it. Airplane pilots are the ones who really appreciate vacuum, as the attitude indicator and gyrocompass depend on it. That third dimension that planes operate in complicates things. Consequences of a mistake tend to be final.
I found the above in an internet Google search of "th400 cam modulator", if you want to confirm. There also is purported to exist a cable operated modulator for the TH400. Assumption here is the the TH400 bears family resemblance to the TH425.
Since you must live at altitude, the problem might just fix itself when you get into lower altitude, there being more air molecules packed per cubic inch down there on the outside of the vacuum pump. I will let the physicists tell us for sure.
You don't live off "Wild Dog Road" near Madrid, NM, do you? If so, Johnny Bridges wants to visit. He's got a couple of dogs who want to meet....No just leave it at that. Bring some turquoise to Montgomery. Good luck with the TH425.
Carey from Ennis, Texas
78 Royale, 500 Cadillac, Rance Baxter EFI.
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