It was not a cracked intake- it was the carb. now what?

[dave silva]

This coach had been fully rebuilt and then parked for seven years when i got it.

This made it hard to troubleshoot. It would run OK and then bog down. So of course we looked at fuel lines, filters, old gas etc.

Got all that sorted still no change. Chased vac leaks etc. No change.

Then someone suggested a cracked intake- that fit the symptoms perfectly. The issue would get worse as the engine warmed up but also, the severity
would get worse over time. So it made perfect sense that a crack would open more as the engine wormed and get bigger over time.

I scored a good intake and commenced to changing it. And when it was all back together there is NO CHANGEit still does not run right.

So maybe the carb? The Revcon is sitting there, has not been run in over a year. The original Toronado Carb has NEVER been rebuilt, but i swap it
out and the Coach runs PERFECTLY!

Ok, that was a long and winding road. Whatever is going on is happening in the carb ONLY.

Here's the symptoms- engine starts pretty easily, takes off smoothly and accelerates into second gear and then has no more power. If I give it more
gas is bogs down like it's gonna stall.

This gets worse the longer i drive it (lately not more than a couple miles)

This carb was freshly rebuilt for the Coop in 2013. it went 1000 miles and did not move again so I'm not inclined to tear in all apart, it's not like
parts are worn or thousands of gallons of fuel have run through it.

What Say the Brain Trust ?

--
Dave & Ellen Silva
Hertford, NC

76 Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.

 

[B52sRule]

Just for grins look for a crack at the base of the carb.  Been there,
done that.  Took forever to find that.

Len Novak

> This coach had been fully rebuilt and then parked for seven years when i got it.
>
> This made it hard to troubleshoot. It would run OK and then bog down. So of course we looked at fuel lines, filters, old gas etc.
>
> Got all that sorted still no change. Chased vac leaks etc. No change.
>
> Then someone suggested a cracked intake- that fit the symptoms perfectly. The issue would get worse as the engine warmed up but also, the severity
> would get worse over time. So it made perfect sense that a crack would open more as the engine wormed and get bigger over time.
>
> I scored a good intake and commenced to changing it. And when it was all back together there is NO CHANGEit still does not run right.
>
> So maybe the carb? The Revcon is sitting there, has not been run in over a year. The original Toronado Carb has NEVER been rebuilt, but i swap it
> out and the Coach runs PERFECTLY!
>
> Ok, that was a long and winding road. Whatever is going on is happening in the carb ONLY.
>
>
> Here's the symptoms- engine starts pretty easily, takes off smoothly and accelerates into second gear and then has no more power. If I give it more
> gas is bogs down like it's gonna stall.
>
> This gets worse the longer i drive it (lately not more than a couple miles)
>
> This carb was freshly rebuilt for the Coop in 2013. it went 1000 miles and did not move again so I'm not inclined to tear in all apart, it's not like
> parts are worn or thousands of gallons of fuel have run through it.
>
> What Say the Brain Trust ?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
--
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
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
www.bdub.net/novak/

 

[cjv]

Is there any way to satisfactorily repair a cracked manifold?

CJ Vermeulen, Scribbler

From: "Len Novak"
To: "dave silva" , "gmclist"
Sent: Thursday, March 24, 2022 6:20:48 PM
Subject: [GMCnet] Re: It was not a cracked intake- it was the carb. now what?

Just for grins look for a crack at the base of the carb. Been there,
done that. Took forever to find that.

Len Novak

This coach had been fully rebuilt and then parked for seven years when i got it.

This made it hard to troubleshoot. It would run OK and then bog down. So of course we looked at fuel lines, filters, old gas etc.

Got all that sorted still no change. Chased vac leaks etc. No change.

Then someone suggested a cracked intake- that fit the symptoms perfectly. The issue would get worse as the engine warmed up but also, the severity
would get worse over time. So it made perfect sense that a crack would open more as the engine wormed and get bigger over time.

I scored a good intake and commenced to changing it. And when it was all back together there is NO CHANGEit still does not run right.

So maybe the carb? The Revcon is sitting there, has not been run in over a year. The original Toronado Carb has NEVER been rebuilt, but i swap it
out and the Coach runs PERFECTLY!

Ok, that was a long and winding road. Whatever is going on is happening in the carb ONLY.

Here's the symptoms- engine starts pretty easily, takes off smoothly and accelerates into second gear and then has no more power. If I give it more
gas is bogs down like it's gonna stall.

This gets worse the longer i drive it (lately not more than a couple miles)

This carb was freshly rebuilt for the Coop in 2013. it went 1000 miles and did not move again so I'm not inclined to tear in all apart, it's not like
parts are worn or thousands of gallons of fuel have run through it.

What Say the Brain Trust ?

--
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
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
www.bdub.net/novak/
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

 

[Jim Hupy]

There are two kinds of cast iron manifolds. Those that are cracked, and
those that haven't cracked yet. If the cracks are accessible from the
bottom, a hole can be drilled at each end of the crack, "V" ing out the
crack with a die grinder, then tig welding the crack with rod intended for
cast iron repair. Or, use the same prep and use bronze brazing rod. When
you finish, then block off the crossover with stainless steel plates
between the heads and manifold. Some have filled the crossover passage with
poured molten aluminum or other metals. I have not done either of these
methods, but I have practiced on a severely cracked manifold.
If the manifold is cracked through to the intake passages under the
carb, it is tough sledding to get effective welds in there.
Jim Hupy
Salem, Oregon

> Is there any way to satisfactorily repair a cracked manifold?
>
> CJ Vermeulen, Scribbler
>
>
> From: "Len Novak"
> To: "dave silva" , "gmclist"
> Sent: Thursday, March 24, 2022 6:20:48 PM
> Subject: [GMCnet] Re: It was not a cracked intake- it was the carb. now
> what?
>
> Just for grins look for a crack at the base of the carb. Been there,
> done that. Took forever to find that.
>
>
> Len Novak
>
>
>

>
>
> This coach had been fully rebuilt and then parked for seven years when i
> got it.
>
> This made it hard to troubleshoot. It would run OK and then bog down. So
> of course we looked at fuel lines, filters, old gas etc.
>
> Got all that sorted still no change. Chased vac leaks etc. No change.
>
> Then someone suggested a cracked intake- that fit the symptoms perfectly.
> The issue would get worse as the engine warmed up but also, the severity
> would get worse over time. So it made perfect sense that a crack would
> open more as the engine wormed and get bigger over time.
>
> I scored a good intake and commenced to changing it. And when it was all
> back together there is NO CHANGEit still does not run right.
>
> So maybe the carb? The Revcon is sitting there, has not been run in over a
> year. The original Toronado Carb has NEVER been rebuilt, but i swap it
> out and the Coach runs PERFECTLY!
>
> Ok, that was a long and winding road. Whatever is going on is happening in
> the carb ONLY.
>
>
> Here's the symptoms- engine starts pretty easily, takes off smoothly and
> accelerates into second gear and then has no more power. If I give it more
> gas is bogs down like it's gonna stall.
>
> This gets worse the longer i drive it (lately not more than a couple
> miles)
>
> This carb was freshly rebuilt for the Coop in 2013. it went 1000 miles and
> did not move again so I'm not inclined to tear in all apart, it's not like
> parts are worn or thousands of gallons of fuel have run through it.
>
> What Say the Brain Trust ?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> --
> 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
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
> www.bdub.net/novak/
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[cjv]

Thank you....great info....

CJ Vermeulen, Scribbler

From: "jamesh1296"
To: "gmclist"
Sent: Thursday, March 24, 2022 9:00:28 PM
Subject: [GMCnet] Re: It was not a cracked intake- it was the carb. now what?

There are two kinds of cast iron manifolds. Those that are cracked, and
those that haven't cracked yet. If the cracks are accessible from the
bottom, a hole can be drilled at each end of the crack, "V" ing out the
crack with a die grinder, then tig welding the crack with rod intended for
cast iron repair. Or, use the same prep and use bronze brazing rod. When
you finish, then block off the crossover with stainless steel plates
between the heads and manifold. Some have filled the crossover passage with
poured molten aluminum or other metals. I have not done either of these
methods, but I have practiced on a severely cracked manifold.
If the manifold is cracked through to the intake passages under the
carb, it is tough sledding to get effective welds in there.
Jim Hupy
Salem, Oregon

Is there any way to satisfactorily repair a cracked manifold?

CJ Vermeulen, Scribbler

From: "Len Novak"
To: "dave silva" , "gmclist"
Sent: Thursday, March 24, 2022 6:20:48 PM
Subject: [GMCnet] Re: It was not a cracked intake- it was the carb. now
what?

Just for grins look for a crack at the base of the carb. Been there,
done that. Took forever to find that.

Len Novak

This coach had been fully rebuilt and then parked for seven years when i
got it.

This made it hard to troubleshoot. It would run OK and then bog down. So
of course we looked at fuel lines, filters, old gas etc.

Got all that sorted still no change. Chased vac leaks etc. No change.

Then someone suggested a cracked intake- that fit the symptoms perfectly.
The issue would get worse as the engine warmed up but also, the severity
would get worse over time. So it made perfect sense that a crack would
open more as the engine wormed and get bigger over time.

I scored a good intake and commenced to changing it. And when it was all
back together there is NO CHANGEit still does not run right.

So maybe the carb? The Revcon is sitting there, has not been run in over a
year. The original Toronado Carb has NEVER been rebuilt, but i swap it
out and the Coach runs PERFECTLY!

Ok, that was a long and winding road. Whatever is going on is happening in
the carb ONLY.

Here's the symptoms- engine starts pretty easily, takes off smoothly and
accelerates into second gear and then has no more power. If I give it more
gas is bogs down like it's gonna stall.

This gets worse the longer i drive it (lately not more than a couple
miles)

This carb was freshly rebuilt for the Coop in 2013. it went 1000 miles and
did not move again so I'm not inclined to tear in all apart, it's not like
parts are worn or thousands of gallons of fuel have run through it.

What Say the Brain Trust ?

--
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
http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
www.bdub.net/novak/
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

 

[jim kanomata1]

Filling intake has never been a worthwhile project.
The best we seen in last few years is a Stainless Steel plate with correct
thickness gasket.
Since we provide everything, we sell the ones Dick Patterson of Springfield
supplies us.
The main cause of hot intake is poor worn blown mufflers as one side can
have high restriction causing exhaust to flow through the intake to the
other side.
Most are using car mufflers as they are less
expensive.
One should be using Truck style as they will hold up.

> There are two kinds of cast iron manifolds. Those that are cracked, and
> those that haven't cracked yet. If the cracks are accessible from the
> bottom, a hole can be drilled at each end of the crack, "V" ing out the
> crack with a die grinder, then tig welding the crack with rod intended for
> cast iron repair. Or, use the same prep and use bronze brazing rod. When
> you finish, then block off the crossover with stainless steel plates
> between the heads and manifold. Some have filled the crossover passage with
> poured molten aluminum or other metals. I have not done either of these
> methods, but I have practiced on a severely cracked manifold.
> If the manifold is cracked through to the intake passages under the
> carb, it is tough sledding to get effective welds in there.
> Jim Hupy
> Salem, Oregon
>

>
> > Is there any way to satisfactorily repair a cracked manifold?
> >
> > CJ Vermeulen, Scribbler
> >
> >
> > From: "Len Novak"
> > To: "dave silva" , "gmclist"
> > Sent: Thursday, March 24, 2022 6:20:48 PM
> > Subject: [GMCnet] Re: It was not a cracked intake- it was the carb. now
> > what?
> >
> > Just for grins look for a crack at the base of the carb. Been there,
> > done that. Took forever to find that.
> >
> >
> > Len Novak
> >
> >
> >

> >
> >
> > This coach had been fully rebuilt and then parked for seven years when i
> > got it.
> >
> > This made it hard to troubleshoot. It would run OK and then bog down. So
> > of course we looked at fuel lines, filters, old gas etc.
> >
> > Got all that sorted still no change. Chased vac leaks etc. No change.
> >
> > Then someone suggested a cracked intake- that fit the symptoms perfectly.
> > The issue would get worse as the engine warmed up but also, the severity
> > would get worse over time. So it made perfect sense that a crack would
> > open more as the engine wormed and get bigger over time.
> >
> > I scored a good intake and commenced to changing it. And when it was all
> > back together there is NO CHANGEit still does not run right.
> >
> > So maybe the carb? The Revcon is sitting there, has not been run in over
> a
> > year. The original Toronado Carb has NEVER been rebuilt, but i swap it
> > out and the Coach runs PERFECTLY!
> >
> > Ok, that was a long and winding road. Whatever is going on is happening
> in
> > the carb ONLY.
> >
> >
> > Here's the symptoms- engine starts pretty easily, takes off smoothly and
> > accelerates into second gear and then has no more power. If I give it
> more
> > gas is bogs down like it's gonna stall.
> >
> > This gets worse the longer i drive it (lately not more than a couple
> > miles)
> >
> > This carb was freshly rebuilt for the Coop in 2013. it went 1000 miles
> and
> > did not move again so I'm not inclined to tear in all apart, it's not
> like
> > parts are worn or thousands of gallons of fuel have run through it.
> >
> > What Say the Brain Trust ?
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > --
> > 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
> > http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
> > www.bdub.net/novak/
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502

 

[jim kanomata1]

One cannot use a car carb as the power valve is set for lower load.
It will run, but dump lot of fuel down the intake.

> Filling intake has never been a worthwhile project.
> The best we seen in last few years is a Stainless Steel plate with correct
> thickness gasket.
> Since we provide everything, we sell the ones Dick Patterson of
> Springfield supplies us.
> The main cause of hot intake is poor worn blown mufflers as one side can
> have high restriction causing exhaust to flow through the intake to the
> other side.
> Most are using car mufflers as they are less
> expensive.
> One should be using Truck style as they will hold up.
>

>
>> There are two kinds of cast iron manifolds. Those that are cracked, and
>> those that haven't cracked yet. If the cracks are accessible from the
>> bottom, a hole can be drilled at each end of the crack, "V" ing out the
>> crack with a die grinder, then tig welding the crack with rod intended for
>> cast iron repair. Or, use the same prep and use bronze brazing rod. When
>> you finish, then block off the crossover with stainless steel plates
>> between the heads and manifold. Some have filled the crossover passage
>> with
>> poured molten aluminum or other metals. I have not done either of these
>> methods, but I have practiced on a severely cracked manifold.
>> If the manifold is cracked through to the intake passages under the
>> carb, it is tough sledding to get effective welds in there.
>> Jim Hupy
>> Salem, Oregon
>>

>>
>> > Is there any way to satisfactorily repair a cracked manifold?
>> >
>> > CJ Vermeulen, Scribbler
>> >
>> >
>> > From: "Len Novak"
>> > To: "dave silva" , "gmclist"
>> > Sent: Thursday, March 24, 2022 6:20:48 PM
>> > Subject: [GMCnet] Re: It was not a cracked intake- it was the carb. now
>> > what?
>> >
>> > Just for grins look for a crack at the base of the carb. Been there,
>> > done that. Took forever to find that.
>> >
>> >
>> > Len Novak
>> >
>> >
>> >

>> >
>> >
>> > This coach had been fully rebuilt and then parked for seven years when i
>> > got it.
>> >
>> > This made it hard to troubleshoot. It would run OK and then bog down. So
>> > of course we looked at fuel lines, filters, old gas etc.
>> >
>> > Got all that sorted still no change. Chased vac leaks etc. No change.
>> >
>> > Then someone suggested a cracked intake- that fit the symptoms
>> perfectly.
>> > The issue would get worse as the engine warmed up but also, the severity
>> > would get worse over time. So it made perfect sense that a crack would
>> > open more as the engine wormed and get bigger over time.
>> >
>> > I scored a good intake and commenced to changing it. And when it was all
>> > back together there is NO CHANGEit still does not run right.
>> >
>> > So maybe the carb? The Revcon is sitting there, has not been run in
>> over a
>> > year. The original Toronado Carb has NEVER been rebuilt, but i swap it
>> > out and the Coach runs PERFECTLY!
>> >
>> > Ok, that was a long and winding road. Whatever is going on is happening
>> in
>> > the carb ONLY.
>> >
>> >
>> > Here's the symptoms- engine starts pretty easily, takes off smoothly and
>> > accelerates into second gear and then has no more power. If I give it
>> more
>> > gas is bogs down like it's gonna stall.
>> >
>> > This gets worse the longer i drive it (lately not more than a couple
>> > miles)
>> >
>> > This carb was freshly rebuilt for the Coop in 2013. it went 1000 miles
>> and
>> > did not move again so I'm not inclined to tear in all apart, it's not
>> like
>> > parts are worn or thousands of gallons of fuel have run through it.
>> >
>> > What Say the Brain Trust ?
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > --
>> > 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
>> > http://www.gmcmhphotos.com/photos/showgallery.php?cat=4375
>> > www.bdub.net/novak/
>> > _______________________________________________
>> > GMCnet mailing list
>> > Unsubscribe or Change List Options:
>> > _______________________________________________
>> > GMCnet mailing list
>> > Unsubscribe or Change List Options:
>> >
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
>
>
> --
> Jim Kanomata ASE
> Applied/GMC, Newark,CA
> jimk
> http://www.gmcrvparts.com
> 1-800-752-7502
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502

 

[johnny]

I'd do the quick cheap and dirty first - replace the filter in the carb inlet. Still have trouble, check the carb base for warping, if it's flat send
it to a competent builder. Dick Patterson comes to mid. Or consider an upgrade to fuel injection.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

 

[john r. lebetski]

Guessing using data provided. Stuck power valve piston. Easy fix. Runs ok with choke on cold. As it warm up the rods are not moving up and down and
as choke opens it goes flat as you open throttle.
20 mins to remove carb
20 mins to clean bench off
20 mins to open carb and remove and spray power valve and all passages
20 mins to reinstall carb.
(Generous time scales)
If carb was rebuilt as recently as you say, I bet the top gasket is still reusable. Spray straw all the emulsion tubes and passages w carb cleaner
while apart. If you have not worked on Qjets feel free to ask any questions. Hidden screws etc.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[dave silva]

> Guessing using data provided. Stuck power valve piston. Easy fix. Runs ok with choke on cold. As it warm up the rods are not moving up and down
> and as choke opens it goes flat as you open throttle.
> 20 mins to remove carb
> 20 mins to clean bench off
> 20 mins to open carb and remove and spray power valve and all passages
> 20 mins to reinstall carb.
> (Generous time scales)
> If carb was rebuilt as recently as you say, I bet the top gasket is still reusable. Spray straw all the emulsion tubes and passages w carb cleaner
> while apart. If you have not worked on Qjets feel free to ask any questions. Hidden screws etc.

This is the answer i was hoping for.

I have very little carb experience but lots of experience opening up things i know nothing about.

I'll do some reasearch and get into itthis weekend- thanks

--
Dave & Ellen Silva
Hertford, NC

76 Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.

 

[T McManus]

In the many years of dealing with automotive repairs, 50% of the time there is more than one thing causing the problem. It makes fixing things more
interesting.
--
Tom McManus
1977 Royale

Chesapeake VA

 

[john r. lebetski]

There are 2 “hidden” screws in the primary throats. Don’t pry anything. If primary plunger is stuck down, spray in there as best you can. To
remove it it needs to be free. You push down with finger and side step it it it pops the retainer out. To reinstall get rods in jets and depress with
finger while reseating the plastic or phenolic retainer.
Remember only “2 fingers tight” mounting the carb to avoid warping.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Jim Hupy]

If you are separating the throttle body from the float bowl, there is also
a screw in the near exact middle of the throttle body pointing upwards from
the gasket surface between the throttle body and manifold. That screw is
frequently loose and contributes to carb base warpage and fuel leaks. Don't
ask me how I learned this one.
Jim Hupy
Salem, Oregon

On Fri, Mar 25, 2022, 7:56 AM John R. Lebetski
wrote:

> There are 2 “hidden” screws in the primary throats. Don’t pry anything. If
> primary plunger is stuck down, spray in there as best you can. To
> remove it it needs to be free. You push down with finger and side step it
> it it pops the retainer out. To reinstall get rods in jets and depress with
> finger while reseating the plastic or phenolic retainer.
> Remember only “2 fingers tight” mounting the carb to avoid warping.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[jim kanomata1]

If your going to run a Toronado carb, your fuel consumption will be high
unless you replace the Power valve.

> If you are separating the throttle body from the float bowl, there is also
> a screw in the near exact middle of the throttle body pointing upwards from
> the gasket surface between the throttle body and manifold. That screw is
> frequently loose and contributes to carb base warpage and fuel leaks. Don't
> ask me how I learned this one.
> Jim Hupy
> Salem, Oregon
>
> On Fri, Mar 25, 2022, 7:56 AM John R. Lebetski

>
> > There are 2 “hidden” screws in the primary throats. Don’t pry anything.
> If
> > primary plunger is stuck down, spray in there as best you can. To
> > remove it it needs to be free. You push down with finger and side step it
> > it it pops the retainer out. To reinstall get rods in jets and depress
> with
> > finger while reseating the plastic or phenolic retainer.
> > Remember only “2 fingers tight” mounting the carb to avoid warping.
> > --
> > John Lebetski
> > Woodstock, IL
> > 77 Eleganza II
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502

 

[Matt Colie]

Dave,

Johnny is right about starting with a clear bench..... (BTDT)

I second that it is the power valve part of the circuit, but without hands on, I am not sure where.

There is also http://oldcarmanualproject.com/manuals/Carbs/Rochester/QJet/index.htm that is much like what is in the 7525 manual. I find it a little
clearer in some places.

The only thing I am certain of here is that what you have is clearly repairable. Just take your time and look at everything.

Best of Luck (Yeah, I'd rather be lucky than good.)

Matt
--
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

 

[dave silva]

> If your going to run a Toronado carb, your fuel consumption will be high
> unless you replace the Power valve.

No, definitely not keeping the Toro carb. Just swapped it for trouble shooting- but damn it ran pretty good.

I finally got the coach going fast enough to be terrified by the sloppy steering. Dave Lenzi has shipped a used steering relay.

--
Dave & Ellen Silva
Hertford, NC

76 Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.

 

[Ken B]

The lazy persons way to try before disassembling the carb. I got this from, Dick Paterson.

I had a GMC w/403 engine that sat for 19 years. I got it to start and barely run (very poorly).
I had disconnected the input hose to fuel pump and ran it on a temporary 5 gallon can of clean gasoline resting on the front bumper. With it running
I switched the fuel input to straight carb cleaner and ran it at about 2000 rpm until the engine died. Then I let it soak for 24 hours.

The next day I reconnected the clean gas can to the fuel pump and cranked, and cranked, and cranked until some of the carb cleaner in the carb was
replaced with fresh gas and the engine restarted. The engine now runs perfectly and I wish that my 455 in my own coach ran and started that well.

Try a 24 hour soaking with a carb full of pure carb cleaner before you tear into the carb.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[cjv]

I have done the same thing (but not on an engine that sat for that long!!) Does work like a charm.

CJ Vermeulen, Scribbler

----- Original Message -----
From: "Ken Burton"
To: "gmclist"
Sent: Friday, March 25, 2022 1:43:03 PM
Subject: [GMCnet] Re: It was not a cracked intake- it was the carb. now what?

The lazy persons way to try before disassembling the carb. I got this from, Dick Paterson.

I had a GMC w/403 engine that sat for 19 years. I got it to start and barely run (very poorly).
I had disconnected the input hose to fuel pump and ran it on a temporary 5 gallon can of clean gasoline resting on the front bumper. With it running
I switched the fuel input to straight carb cleaner and ran it at about 2000 rpm until the engine died. Then I let it soak for 24 hours.

The next day I reconnected the clean gas can to the fuel pump and cranked, and cranked, and cranked until some of the carb cleaner in the carb was
replaced with fresh gas and the engine restarted. The engine now runs perfectly and I wish that my 455 in my own coach ran and started that well.

Try a 24 hour soaking with a carb full of pure carb cleaner before you tear into the carb.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:

 

[joe ricke]

Dave S

Not throwing curveballs at you but you may want to pop the distributor cap off and check that weights and springs move freely.
--
Joe Ricke - KE0CPM
Arden Hills, MN
'77 Transmode

 

[john r. lebetski]

Smokey said 9 out of 10 carb problems are ignition.
Jim is correct about faulty mufflers.
And the power valve. BUT besides the power valve spring the GMC used, the GMC was the only Qjet made to use special triple tapered primary rods.
This into from the Doug Roe Rochester carbs book.
--
John Lebetski
Woodstock, IL
77 Eleganza II