Home » Public Forums » GMCnet » Replacement carburetor (Replacement carburetor)
| Replacement carburetor [message #345962] |
Fri, 02 August 2019 17:46  |
tmsnyder
Messages: 151
Registered: January 2014
Karma: -9
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Senior Member |
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I'm thinking of replacing the qjet with a new edelbrock performer carburetor. What kind of fitment issue should I expect?
Did someone mention that the air cleaner will have to be massaged to clear a part of the edelbrock?
Also, the installation instructions say that an adapter plate is required, and it's almost an inch thick. It would seem that the engine cover would no longer fit b/c of the increased height of the new carb. Is this true?
Sorry if this has been covered before, I did search and couldn't find anyone else's experiences with this in the forum. I'm not really interested in any FI system at this point either, or a rebuild service for a 43 year old carburetor.
Any useful information would be appreciated!
Todd Snyder, Buffalo NY
1976 Eleganza II
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| Re: [GMCnet] Replacement carburetor [message #345964 is a reply to message #345962] |
Fri, 02 August 2019 18:09  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Why would you want to perform that swap? That is like a giant leap
backwards. But you may well have your purposes for it. I would be
interested in what they are.
Jim Hupy
Salem, Or
On Fri, Aug 2, 2019, 4:03 PM Todd Snyder via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I'm thinking of replacing the qjet with a new edelbrock performer
> carburetor. What kind of fitment issue should I expect?
>
> Did someone mention that the air cleaner will have to be massaged to clear
> a part of the edelbrock?
>
> Also, the installation instructions say that an adapter plate is required,
> and it's almost an inch thick. It would seem that the engine cover would
> no longer fit b/c of the increased height of the new carb. Is this true?
>
> Sorry if this has been covered before, I did search and couldn't find
> anyone else's experiences with this in the forum. I'm not really interested
> in
> any FI system at this point either, or a rebuild service for a 43 year old
> carburetor.
>
> Any useful information would be appreciated!
> --
> Todd Snyder, Buffalo NY
> 1976 Eleganza II
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] Replacement carburetor [message #345967 is a reply to message #345964] |
Fri, 02 August 2019 20:49 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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What Jim H is saying is that these engine seldom ever rev more than 3,000
RPM.
Most of us that understand engine performance know these and get a chuckle
when people think they understand.
I learned these things in Junior High as we played with cars and made lot
of stupid decision as the older guys use to laugh at us. I'm still learning
from people.
These coaches are designed to work well with the Quadrajet. Just by
dropping in a kit does not really work.
Our Headers are the Low Torque models that are designed to operate
2,500-3,500 rpm.
On Fri, Aug 2, 2019 at 4:08 PM James Hupy via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Why would you want to perform that swap? That is like a giant leap
> backwards. But you may well have your purposes for it. I would be
> interested in what they are.
> Jim Hupy
> Salem, Or
>
> On Fri, Aug 2, 2019, 4:03 PM Todd Snyder via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> I'm thinking of replacing the qjet with a new edelbrock performer
>> carburetor. What kind of fitment issue should I expect?
>>
>> Did someone mention that the air cleaner will have to be massaged to
> clear
>> a part of the edelbrock?
>>
>> Also, the installation instructions say that an adapter plate is
> required,
>> and it's almost an inch thick. It would seem that the engine cover would
>> no longer fit b/c of the increased height of the new carb. Is this true?
>>
>> Sorry if this has been covered before, I did search and couldn't find
>> anyone else's experiences with this in the forum. I'm not really
> interested
>> in
>> any FI system at this point either, or a rebuild service for a 43 year
> old
>> carburetor.
>>
>> Any useful information would be appreciated!
>> --
>> Todd Snyder, Buffalo NY
>> 1976 Eleganza II
>>
>> _______________________________________________
>> 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:
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Replacement carburetor [message #345968 is a reply to message #345967] |
Fri, 02 August 2019 21:06 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Todd,
I hope I'm not pissing you off.
I am a Degreed Engineer and get lot of shit from technicians as most
engineers don't know enough simple basic things, but act like they do.
I learned long time ago that a good technician can analyze a problem better
than an engineer.
Just to prove to my mechanics that I know automotive things, I took the ASE
test with them and scored higher.
On Fri, Aug 2, 2019 at 6:49 PM Jim Kanomata wrote:
> What Jim H is saying is that these engine seldom ever rev more than 3,000
> RPM.
> Most of us that understand engine performance know these and get a chuckle
> when people think they understand.
> I learned these things in Junior High as we played with cars and made lot
> of stupid decision as the older guys use to laugh at us. I'm still learning
> from people.
> These coaches are designed to work well with the Quadrajet. Just by
> dropping in a kit does not really work.
> Our Headers are the Low Torque models that are designed to operate
> 2,500-3,500 rpm.
>
> On Fri, Aug 2, 2019 at 4:08 PM James Hupy via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Why would you want to perform that swap? That is like a giant leap
>> backwards. But you may well have your purposes for it. I would be
>> interested in what they are.
>> Jim Hupy
>> Salem, Or
>>
>> On Fri, Aug 2, 2019, 4:03 PM Todd Snyder via Gmclist > gmclist@list.gmcnet.org> wrote:
>>
>>> I'm thinking of replacing the qjet with a new edelbrock performer
>>> carburetor. What kind of fitment issue should I expect?
>>>
>>> Did someone mention that the air cleaner will have to be massaged to
>> clear
>>> a part of the edelbrock?
>>>
>>> Also, the installation instructions say that an adapter plate is
>> required,
>>> and it's almost an inch thick. It would seem that the engine cover
>> would
>>> no longer fit b/c of the increased height of the new carb. Is this
>> true?
>>>
>>> Sorry if this has been covered before, I did search and couldn't find
>>> anyone else's experiences with this in the forum. I'm not really
>> interested
>>> in
>>> any FI system at this point either, or a rebuild service for a 43 year
>> old
>>> carburetor.
>>>
>>> Any useful information would be appreciated!
>>> --
>>> Todd Snyder, Buffalo NY
>>> 1976 Eleganza II
>>>
>>> _______________________________________________
>>> 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
>>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Replacement carburetor [message #345977 is a reply to message #345971] |
Sat, 03 August 2019 06:55 |
tmsnyder
Messages: 151
Registered: January 2014
Karma: -9
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Senior Member |
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Can you explain your opinion as to why 'it won't work'?
As I understand it, it's a 4 barrel carburetor, designed directly from the Qjet, except with improvements to make tuning much easier.
And please also explain why you feel this carburetor won't work, but TBI FI systems are fine in this application.
Todd Snyder, Buffalo NY
1976 Eleganza II
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| Re: [GMCnet] Replacement carburetor [message #345980 is a reply to message #345977] |
Sat, 03 August 2019 07:57 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
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Senior Member |
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Todd,
As I understand it, the GMC Motorhome (TZE) specific quadrajet has a modified fuel enrichment circuit (powervalve) that provides fuel enrichment sooner than most other carbs. Installing an “out of the box”carb of another type without reworking it to match the original GMC specs will potentially result in lean burn conditions during light acceleration and cruise. This could result in major engine damage.
To rework another carb type and get it right will require an oxygen sensor to read air/fuel ratios, and good knowledge of plug reading and carb tuning. By the time you are done, you’ll have spent enormous time and money on an item that could easily have been replaced with a GMC Motorhome quadrajet rebuild from a reputable vendor. There is no reason why a 45 yr old carb can’t be made reliable. It just takes the correct skills and parts to get it done.
Another fact that stacks against your quest is the fact that if using another type of carb was an easy solution, the reputable and experienced GMC vendors would be offering those carbs as an alternative.
Regarding TBI FI swaps. The older GM based TBI units only run well once the fuel maps have been tweaked to match the application. You can’t just install a used TBI system from another application and expect it to run correctly. Swaps are rarely a bolt-on and go affair. U
I strongly suggest you do some searching into the older posts in this GMCNet forum. Carbs and TBI systems have been discussed repeatedly in great detail and all of what I mentioned above comes from info previously discussed here. If you dig deep enough, you’ll get a better idea of what you need to do.
Les Burt
Montreal
'75 Eleganza 26'
> On Aug 3, 2019, at 7:55 AM, Todd Snyder via Gmclist wrote:
>
> Can you explain your opinion as to why 'it won't work'?
>
> As I understand it, it's a 4 barrel carburetor, designed directly from the Qjet, except with improvements to make tuning much easier.
>
> And please also explain why you feel this carburetor won't work, but TBI FI systems are fine in this application.
> --
> Todd Snyder, Buffalo NY
> 1976 Eleganza II
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: Replacement carburetor [message #345985 is a reply to message #345962] |
Sat, 03 August 2019 08:28 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Todd, pay attention to what's said above. Personally, I like Carter carburetors. As I've noted in another thread, by the time I got an AFB properly set up to equal (much less surpass) the Q-jet performance >using the proper Q-jet by part number for the coach< I will need a flow bench and several hours of time to get close and then many miles hoping I don't burn something essential in the engine testing which would equal what's already off the shelf available from our vendors.
Can it be done? Sure, with time and money. However, why would you do it?
As to fuel injection, The bolton aftermarket systems work fairly well and are less finicky about alcohol in the gas. The GM throttle body system can be made to work using the information and maps people have developed... again available. And after a bit of turning a trouble many show about a ten percent increase in mileage - from 8 to 9:) If you're a tinkerer, much of that system can be sourced at the local Men's Mall. Or it can be bought complete from the vendors.
I suggest you invent your time in either a properly rebuilt Q-jet, or an injection system. Worrying with the Holley is sorta like putting a Tonowanda Turd in a GMC. It's been done, but why?"
--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
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| Re: [GMCnet] Replacement carburetor [message #345996 is a reply to message #345985] |
Sat, 03 August 2019 09:27 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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I read that he bought the carb already and looking for adapter to mount to
the intake.
He is too smart to listen to those that have done these things 30 -40 years
ago.
Same goes with people buying the simple EFI not knowing what is out there
that works and deliver more advantages over a fuel squart gun.
I'm sure what I say will upset lot of people, but know there are
considerable people that back me up on the comments.
Considerable amount of my comment is backed by people that never get on the
net,
On Sat, Aug 3, 2019 at 6:52 AM Johnny Bridges via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Todd, pay attention to what's said above. Personally, I like Carter
> carburetors. As I've noted in another thread, by the time I got an AFB
> properly
> set up to equal (much less surpass) the Q-jet performance >using the
> proper Q-jet by part number for the coach< I will need a flow bench and
> several
> hours of time to get close and then many miles hoping I don't burn
> something essential in the engine testing which would equal what's already
> off the
> shelf available from our vendors.
>
> Can it be done? Sure, with time and money. However, why would you do it?
>
> As to fuel injection, The bolton aftermarket systems work fairly well and
> are less finicky about alcohol in the gas. The GM throttle body system can
> be made to work using the information and maps people have developed...
> again available. And after a bit of turning a trouble many show about a ten
> percent increase in mileage - from 8 to 9:) If you're a tinkerer, much of
> that system can be sourced at the local Men's Mall. Or it can be bought
> complete from the vendors.
>
> I suggest you invent your time in either a properly rebuilt Q-jet, or an
> injection system. Worrying with the Holley is sorta like putting a
> Tonowanda
> Turd in a GMC. It's been done, but why?"
>
> --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
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Replacement carburetor [message #346001 is a reply to message #345962] |
Sat, 03 August 2019 10:12 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Jim, the Howell setup is merely one more squirt gun, albeit with a substantially better control system for those who wish to mess with it. The Atomic that was fitted to my current coach answered the problems it was put on for - much better starting, better hot weather performance, 'set and forget'. The FiTech unit saves roughly $1300 over the Howell. Saves me $11 roughly per fill up, meaning it pays out in roughly 120 fill ups. One can do the arithmetic to see if it's worth while. The Howell will take about three times the time to install and tune to run.
--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
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| Re: [GMCnet] Replacement carburetor [message #346004 is a reply to message #346001] |
Sat, 03 August 2019 10:39 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Todd, I merely posed the question, Why? I am sure you have your reasons and
justification for them. I am curious, not being critical, of your decision.
With sufficient motivation and economic resources, almost anything is
POSSIBLE. It does not have to please anyone but you.
I have seen a number of carb swaps on GMC motorhomes. Most require
replacement of everything from fuel lines, throttle linkages, cruise
control transducers, engine hatch covers, air cleaners, emission controls,
vacuum lines, intake manifolds, and probably a few more.
Results? Usually poorer performance and higher fuel consumption. But,
perhaps you have discovered the key that has gone undiscovered for so many
of us. I mean you no disrespect, believe me.
Jim Hupy
Salem, Or
On Sat, Aug 3, 2019, 8:13 AM Johnny Bridges via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Jim, the Howell setup is merely one more squirt gun, albeit with a
> substantially better control system for those who wish to mess with it.
> The Atomic
> that was fitted to my current coach answered the problems it was put on
> for - much better starting, better hot weather performance, 'set and
> forget'.
> The FiTech unit saves roughly $1300 over the Howell. Saves me $11 roughly
> per fill up, meaning it pays out in roughly 120 fill ups. One can do the
> arithmetic to see if it's worth while. The Howell will take about three
> times the time to install and tune to run.
>
> --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
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Replacement carburetor [message #346008 is a reply to message #346004] |
Sat, 03 August 2019 10:56 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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John,
We sell and install ALL EFI units so I address it from feed back I receive
and personal experiences.
Your improvement in milage is possibly from the fact that the origional
carb was not functioning properly.
I'm sure you did some timing adjustment when you installed the unit.
Lets not debate this here.
On Sat, Aug 3, 2019 at 8:38 AM James Hupy via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Todd, I merely posed the question, Why? I am sure you have your reasons and
> justification for them. I am curious, not being critical, of your decision.
> With sufficient motivation and economic resources, almost anything is
> POSSIBLE. It does not have to please anyone but you.
> I have seen a number of carb swaps on GMC motorhomes. Most require
> replacement of everything from fuel lines, throttle linkages, cruise
> control transducers, engine hatch covers, air cleaners, emission controls,
> vacuum lines, intake manifolds, and probably a few more.
> Results? Usually poorer performance and higher fuel consumption. But,
> perhaps you have discovered the key that has gone undiscovered for so many
> of us. I mean you no disrespect, believe me.
> Jim Hupy
> Salem, Or
>
> On Sat, Aug 3, 2019, 8:13 AM Johnny Bridges via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Jim, the Howell setup is merely one more squirt gun, albeit with a
>> substantially better control system for those who wish to mess with it.
>> The Atomic
>> that was fitted to my current coach answered the problems it was put on
>> for - much better starting, better hot weather performance, 'set and
>> forget'.
>> The FiTech unit saves roughly $1300 over the Howell. Saves me $11
> roughly
>> per fill up, meaning it pays out in roughly 120 fill ups. One can do the
>> arithmetic to see if it's worth while. The Howell will take about three
>> times the time to install and tune to run.
>>
>> --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
>>
>>
>> _______________________________________________
>> 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
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Replacement carburetor [message #346011 is a reply to message #345962] |
Sat, 03 August 2019 12:02 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Sir: our new to us 76 Eleganza ll came to us with an 750 cfm Edelbrock #1411 carb on a hi rise aluminum Edelbrock intake with raised floor. When Mr. Beaver rebuilt the engine I found no need to replace it. We now have ~ 10k on the engine with no issues. Starts immediately, runs smooth, plenty of power. It is noisy with the open element air filter. We usually pull a Tracker or a trailer with golf cart so gas mileage is bout same as our 23' Crestmont with OEM intake and Q-jet pulling the same load. The Edelbrock is very simple to swap jets and needles. I have tried changing to a leaner setting to help mpg but got a hesitation till fully warm but still felt sluggish so I went back to jets and needles recommended by Edelbrock.
tmsnyder wrote on Fri, 02 August 2019 18:46I'm thinking of replacing the qjet with a new edelbrock performer carburetor. What kind of fitment issue should I expect?
Did someone mention that the air cleaner will have to be massaged to clear a part of the edelbrock?
Also, the installation instructions say that an adapter plate is required, and it's almost an inch thick. It would seem that the engine cover would no longer fit b/c of the increased height of the new carb. Is this true?
Sorry if this has been covered before, I did search and couldn't find anyone else's experiences with this in the forum. I'm not really interested in any FI system at this point either, or a rebuild service for a 43 year old carburetor.
Any useful information would be appreciated!
C. Boyd
76 Crestmont
East Tennessee
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| Re: Replacement carburetor [message #346018 is a reply to message #345962] |
Sat, 03 August 2019 17:51 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Your older Vic Edelbrock carb may be ok, but the general consensus is the new ones are junk.
I have been driving GM with Qjets since 1969 and adjusting them. Notice I did not say repairing. There is little to break so I seldom need to. The only external user adjustments are idle mixture, idle speed, fast idle speed, choke amount, choke pulloff adjust (very important) and choke unloader amount.
What is your specific issue and symptoms? Might be an easy no cost fix. Most coaches I look at are barely opening the carb secondaries due to bad accelerator linkage and cable adjustment
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Replacement carburetor [message #346019 is a reply to message #345962] |
Sat, 03 August 2019 17:55 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Also some Quadrejets were built by Carter when Rochester could not meet demand for GM. They were used in so many applications.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Replacement carburetor [message #346024 is a reply to message #345962] |
Sun, 04 August 2019 06:56 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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Senior Member |
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Also a big Q jet fan here. Have run them for years, and suckered more than a few guys in street racing back when I was young and stupid because they assumed it wasnt fast with a QJ.
ICarbs come down to airflow, adjustability, and reliability.
You wont gain any airflow with a carter- in fact for a 12K# brick you might be better off with a 600 anyway. Carters are faster to tune but Q jets arent that difficult either.
I think the Q jet is pretty sophisicated in how it meters fuel. THe smaller primary gives better velocity.
Edelbrick did offer new QJ at one time. But like any carb nort specific to the application, you would need to tune it.
THe usual recomendation is to get the right carb from Patterson and let it eat. I think mine was from him originally and has been no problem at all. THat said, if I was looking to spend that much money now I would try the Fitech
I had a performer manifold I was going to swap and decided against it. Talked to the edelbrock tecjh folks about it who did feel that there would be ~ 10Ft/# better true at 2500-3000. Im not opposed to raising the hatch, but decided it wasnt woeth the effort just for that. If I needed a new manifold anyway, sure.
Most of us in this communuty seem to be tinkerers and many of us go against the conventional wisdom of the group at times.... with varying results. Good luck.
76 Glenbrook
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| Re: Replacement carburetor [message #346033 is a reply to message #346024] |
Sun, 04 August 2019 10:58 |
tmsnyder
Messages: 151
Registered: January 2014
Karma: -9
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Senior Member |
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Huh, I would have thought this was a fairly straightforward topic.
Jim H, only reason I'm thinking about this is b/c the qjet is 43 years old. Spending 100's on a rebuild, to me, makes about as much sense as spending $10k on surgery for a 16 year old dog. As much as I love my dog and the qjet, at some point it doesn't make sense and it might be time to look for an affordable replacement for the carb. Maybe it doesn't exist? I don't know. But I would have thought that a new Edelbrock, which is based off the qjet and operates in an almost identical fashion, could be a good replacement with the correct jets/springs/needles. Maybe off the shelf they aren't set up properly for the 455, something to think about, true.
I should have mentioned that it's getting an 02 sensor and afr gauge so tuning of any carburetor would be a bit easier. I'm not interested in 0-60 times, only safe afr's to prevent engine damage and some reasonable economy.
The reason I asked about the spacer is b/c I'm not super interested in modifying the engine cover. If a replacement carb would require a raised cover, then it becomes less appealing to me. Would prefer to keep everything as stock as possible in the living space. Moving fuel tubing around, throttle cable, etc doesn't bother me.
Les: I had mentioned not being interested in a TBI FI system and you assumed a swap from a GM vehicle. What I meant was all the aftermarket FI systems offered for the GMC motorhome are TBI. Maybe I'm wrong, please correct me if so, but the Howell appears to be, as well as the Sniper and the like. They are all TBI. I wasn't suggesting grabbing a TBI system from a junkyard and putting it in, I meant the aftermarket systems.
Johnny: I'm not considering a Holley.
JimK: you wrote "I read that he bought the carb already and looking for adapter to mount to the intake. He is too smart to listen to those that have done these things 30 -40 years ago."
I actually have not purchased any carb, only wrote that I was just thinking about it. And I'm not searching for the adapter plate, it's specified by the manufacturer as required for the application. As to not listening, Im trying to make an informed decision by asking here on this forum if that's ok? Maybe I'm in the wrong place? I would certainly like to learn anything you have to offer, that is in fact why I'm here. If I didn't want to listen I wouldn't be here, but it would be helpful if the answer wasn't 'thats a bad idea' with no information as to why it's a bad idea.
JohnL: symptoms are very poor running, hesitation on acceleration, would only run decent at WOT.
In the meantime I've disassembled and cleaned the carb. Inside I found a torn accelerator pump cup and the primary power piston stuck fast. And everything coated with a rust film from my rusty gas tanks. Can't believe it ran at all. I've dropped the tanks and am cleaning them out now and replacing the fuel/vent/generator lines, selector valve and pump, sending units. The tanks had about 1" of rust flakes and sludge on the bottom, both socks on the sending units were plugged up and ripped open. It's a total mess.
Todd Snyder, Buffalo NY
1976 Eleganza II
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| Re: [GMCnet] Replacement carburetor [message #346035 is a reply to message #346033] |
Sun, 04 August 2019 13:04 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Todd,
I don't pretend to be a carb expert at all; never even liked fooling with
them. And, in fact, I no longer even run an Olds engine, having converted
to a Cad500 with GM/EBL TBI. But I have been a GMC owner for 20+ years
now, always active here on GMCNet. So, I've heard a lot of folks'
experiences. Most importantly, I've heard Dick Paterson (MR. GMC CARB)
discuss several times his efforts to replace the GMC carb. Even replacing
the GMC-specific model with one from a Toronado proved unsatisfactory --
there are different air passage, the needles are different, and probably
other variations that mean nothing to me. The point is that if Dick, with
all his GM Technician background, GMCMH experience, racing experience, and
test equipment can't make it work well, I personally wouldn't even try.
Now converting to a user-programmable GM 7712247 ECU with the EBL
enhancements, that's a whole 'nother question -- especially for someone
with an extensive computer background.
Another point: When I bought the GMC in '98 it had the raised engine cover
necessitated by the Edelbrock Performer manifold with which it was
equipped. We HATED it! Finding the cracks in the Edelbrock's exhaust
crossover was almost a blessing since it was another excuse to go back to
an old iron manifold. :-)
I'm sure you'll have fun with an Edelbrock or other carb. Please keep us
posted. Oh -- and don't be annoyed by any negative comments you may
receive; I can assure you that they're meant to be helpful, even when not
worded diplomatically.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com
On Sun, Aug 4, 2019 at 12:22 PM Todd Snyder via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Huh, I would have thought this was a fairly straightforward topic.
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Replacement carburetor [message #346036 is a reply to message #346035] |
Sun, 04 August 2019 13:37 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Todd, sometime, perhaps when we are both in the same place at the same
time, I will relate to you several examples of my own learning experiences
with carb swaps. Nearly all turned out no better than the OEM provided.
Jim Hupy
Salem, Or.
On Sun, Aug 4, 2019, 11:05 AM Ken Henderson via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Todd,
>
> I don't pretend to be a carb expert at all; never even liked fooling with
> them. And, in fact, I no longer even run an Olds engine, having converted
> to a Cad500 with GM/EBL TBI. But I have been a GMC owner for 20+ years
> now, always active here on GMCNet. So, I've heard a lot of folks'
> experiences. Most importantly, I've heard Dick Paterson (MR. GMC CARB)
> discuss several times his efforts to replace the GMC carb. Even replacing
> the GMC-specific model with one from a Toronado proved unsatisfactory --
> there are different air passage, the needles are different, and probably
> other variations that mean nothing to me. The point is that if Dick, with
> all his GM Technician background, GMCMH experience, racing experience, and
> test equipment can't make it work well, I personally wouldn't even try.
> Now converting to a user-programmable GM 7712247 ECU with the EBL
> enhancements, that's a whole 'nother question -- especially for someone
> with an extensive computer background.
>
> Another point: When I bought the GMC in '98 it had the raised engine cover
> necessitated by the Edelbrock Performer manifold with which it was
> equipped. We HATED it! Finding the cracks in the Edelbrock's exhaust
> crossover was almost a blessing since it was another excuse to go back to
> an old iron manifold. :-)
>
> I'm sure you'll have fun with an Edelbrock or other carb. Please keep us
> posted. Oh -- and don't be annoyed by any negative comments you may
> receive; I can assure you that they're meant to be helpful, even when not
> worded diplomatically.
>
> Ken H.
> Americus, GA
> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
> www.gmcwipersetc.com
>
>
> On Sun, Aug 4, 2019 at 12:22 PM Todd Snyder via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Huh, I would have thought this was a fairly straightforward topic.
>>
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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