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| [GMCnet] Good engine destroyed. Yours could be next. [message #363871] |
Sat, 08 May 2021 09:44  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
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Senior Member |
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I got a call from someone today. That severally damaged a real good running 455. That I built for him 2 years ago. That engine is now trash. When the engine was going in. I pleaded with him to put a GM/Howel EFI system in. His response was. " My carb works great. It's been working to perfection. The carb was rebuilt last year. By someone that knows them well." I should keep my mouth shut on this. As I could go on for days. Over engines. On ways to extend your engines service life. But I'm just sick of this happening. I now know of 4 good engines destroyed in this manner. In the last few years. Engines are my thing. I could post a lot on engines. But it's best that I not. I push GM engines way past their design paramotors. And don't destroy them.
Sorry. I digress. That stock Q jet has always been considered to be one of the finest carbs ever built. As to controlling the air/fuel ratios. Over its entire operating range.
The general though. Is that the carb dumps an air/fuel mixture into an open chamber. That's in the intake manifold. Well. Not really. The Q jet that came on the GMC. Are really two carbs in one aluminum casting. Thus. The left carb feeds 2 cylinders on each side of the engine. The right side feeds the other remaining 4 cylinders.
The problem is that if one side of the carb goes lean. And starts burning up its 4 cylinders. You'll have absolutely no idea of the in pending destruction. Till it's just too late. With the GM/Howell system. The engine check light will come on. To let you know of any issues. Then tell you what's wrong.
Engine service life before the mid 80's was under 100,000 miles. Then in the late 80's. EFI came along. Then service life more than doubled. Yes. Other things that helped. But EFI was the BIGGY. If you wish to talk on this issue. Contact me direct. Not on the net. Or 319-521=4891 Cell.
Bob Dunahugh
78 Royale since 2003
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| [GMCnet] Re: Good engine destroyed. Yours could be next. [message #363872 is a reply to message #363871] |
Sat, 08 May 2021 10:13  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Bob,
So what did the carb do that trashed the engine???
On Sat, May 8, 2021 at 7:44 AM Bob Dunahugh wrote:
> I got a call from someone today. That severally damaged a real good
> running 455. That I built for him 2 years ago. That engine is now trash.
> When the engine was going in. I pleaded with him to put a GM/Howel EFI
> system in. His response was. " My carb works great. It's been working to
> perfection. The carb was rebuilt last year. By someone that knows them
> well." I should keep my mouth shut on this. As I could go on for days.
> Over engines. On ways to extend your engines service life. But I'm just
> sick of this happening. I now know of 4 good engines destroyed in this
> manner. In the last few years. Engines are my thing. I could post a lot on
> engines. But it's best that I not. I push GM engines way past their design
> paramotors. And don't destroy them.
>
> Sorry. I digress. That stock Q jet has always been considered to be
> one of the finest carbs ever built. As to controlling the air/fuel ratios.
> Over its entire operating range.
> The general though. Is that the carb dumps an air/fuel mixture into
> an open chamber. That's in the intake manifold. Well. Not really. The Q
> jet that came on the GMC. Are really two carbs in one aluminum casting.
> Thus. The left carb feeds 2 cylinders on each side of the engine. The right
> side feeds the other remaining 4 cylinders.
> The problem is that if one side of the carb goes lean. And starts
> burning up its 4 cylinders. You'll have absolutely no idea of the in
> pending destruction. Till it's just too late. With the GM/Howell system.
> The engine check light will come on. To let you know of any issues. Then
> tell you what's wrong.
> Engine service life before the mid 80's was under 100,000 miles. Then
> in the late 80's. EFI came along. Then service life more than doubled.
> Yes. Other things that helped. But EFI was the BIGGY. If you wish to talk
> on this issue. Contact me direct. Not on the net. Or 319-521=4891 Cell.
> Bob Dunahugh
> 78 Royale since 2003
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.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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| [GMCnet] Re: Good engine destroyed. Yours could be next. [message #363873 is a reply to message #363872] |
Sat, 08 May 2021 11:33 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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The stock GMC intake manifold is a split flow design. One side (a Primary
and Secondary) of a quadrajet carb feeds 2 cylinders on each side of the
engine, and the other side (Primary and Secondary) of the quadrajet feeds
the remaining 4 cylinders (2 on each side) of the 455.
So, in a perfect world where the quadrajet is working as the factory
designed it to do, all 8 cylinders receive a correct amount of air/fuel
mixture.
BUT, when the quadrajet is NOT working as designed, (like happens
when well intentioned but uninformed tweakers mess with jets and needles in
an attempt to improve their fuel economy, for example), it is easy for 4
cylinders to go very lean, and toast the whole engine.
Jim Hupy
Salem, Oregon
On Sat, May 8, 2021, 8:13 AM Jim Kanomata wrote:
> Bob,
> So what did the carb do that trashed the engine???
>
> On Sat, May 8, 2021 at 7:44 AM Bob Dunahugh wrote:
>
>> I got a call from someone today. That severally damaged a real good
>> running 455. That I built for him 2 years ago. That engine is now trash.
>> When the engine was going in. I pleaded with him to put a GM/Howel EFI
>> system in. His response was. " My carb works great. It's been working to
>> perfection. The carb was rebuilt last year. By someone that knows them
>> well." I should keep my mouth shut on this. As I could go on for days.
>> Over engines. On ways to extend your engines service life. But I'm just
>> sick of this happening. I now know of 4 good engines destroyed in this
>> manner. In the last few years. Engines are my thing. I could post a lot
> on
>> engines. But it's best that I not. I push GM engines way past their
> design
>> paramotors. And don't destroy them.
>>
>> Sorry. I digress. That stock Q jet has always been considered to be
>> one of the finest carbs ever built. As to controlling the air/fuel
> ratios.
>> Over its entire operating range.
>> The general though. Is that the carb dumps an air/fuel mixture into
>> an open chamber. That's in the intake manifold. Well. Not really. The Q
>> jet that came on the GMC. Are really two carbs in one aluminum casting.
>> Thus. The left carb feeds 2 cylinders on each side of the engine. The
> right
>> side feeds the other remaining 4 cylinders.
>> The problem is that if one side of the carb goes lean. And starts
>> burning up its 4 cylinders. You'll have absolutely no idea of the in
>> pending destruction. Till it's just too late. With the GM/Howell system.
>> The engine check light will come on. To let you know of any issues. Then
>> tell you what's wrong.
>> Engine service life before the mid 80's was under 100,000 miles. Then
>> in the late 80's. EFI came along. Then service life more than doubled.
>> Yes. Other things that helped. But EFI was the BIGGY. If you wish to
> talk
>> on this issue. Contact me direct. Not on the net. Or 319-521=4891 Cell.
>> Bob Dunahugh
>> 78 Royale since 2003
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
>
>
> --
> Jim Kanomata
> Applied/GMC, Newark,CA
> jimk@appliedairfilters.com
> http://www.gmcrvparts.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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| [GMCnet] Re: Good engine destroyed. Yours could be next. [message #363875 is a reply to message #363873] |
Sat, 08 May 2021 13:23 |
Zandr Milewski
Messages: 12
Registered: September 2020
Karma: -1
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Junior Member |
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So, given that failure mode, does the Howell have two O2 sensors, one
per bank?
On 5/8/21 09:33, James Hupy wrote:
> The stock GMC intake manifold is a split flow design. One side (a Primary
> and Secondary) of a quadrajet carb feeds 2 cylinders on each side of the
> engine, and the other side (Primary and Secondary) of the quadrajet feeds
> the remaining 4 cylinders (2 on each side) of the 455.
> So, in a perfect world where the quadrajet is working as the factory
> designed it to do, all 8 cylinders receive a correct amount of air/fuel
> mixture.
> BUT, when the quadrajet is NOT working as designed, (like happens
> when well intentioned but uninformed tweakers mess with jets and needles in
> an attempt to improve their fuel economy, for example), it is easy for 4
> cylinders to go very lean, and toast the whole engine.
> Jim Hupy
> Salem, Oregon
>
>
> On Sat, May 8, 2021, 8:13 AM Jim Kanomata wrote:
>
>> Bob,
>> So what did the carb do that trashed the engine???
>>
>> On Sat, May 8, 2021 at 7:44 AM Bob Dunahugh wrote:
>>
>>> I got a call from someone today. That severally damaged a real good
>>> running 455. That I built for him 2 years ago. That engine is now trash.
>>> When the engine was going in. I pleaded with him to put a GM/Howel EFI
>>> system in. His response was. " My carb works great. It's been working to
>>> perfection. The carb was rebuilt last year. By someone that knows them
>>> well." I should keep my mouth shut on this. As I could go on for days.
>>> Over engines. On ways to extend your engines service life. But I'm just
>>> sick of this happening. I now know of 4 good engines destroyed in this
>>> manner. In the last few years. Engines are my thing. I could post a lot
>> on
>>> engines. But it's best that I not. I push GM engines way past their
>> design
>>> paramotors. And don't destroy them.
>>>
>>> Sorry. I digress. That stock Q jet has always been considered to be
>>> one of the finest carbs ever built. As to controlling the air/fuel
>> ratios.
>>> Over its entire operating range.
>>> The general though. Is that the carb dumps an air/fuel mixture into
>>> an open chamber. That's in the intake manifold. Well. Not really. The Q
>>> jet that came on the GMC. Are really two carbs in one aluminum casting.
>>> Thus. The left carb feeds 2 cylinders on each side of the engine. The
>> right
>>> side feeds the other remaining 4 cylinders.
>>> The problem is that if one side of the carb goes lean. And starts
>>> burning up its 4 cylinders. You'll have absolutely no idea of the in
>>> pending destruction. Till it's just too late. With the GM/Howell system.
>>> The engine check light will come on. To let you know of any issues. Then
>>> tell you what's wrong.
>>> Engine service life before the mid 80's was under 100,000 miles. Then
>>> in the late 80's. EFI came along. Then service life more than doubled.
>>> Yes. Other things that helped. But EFI was the BIGGY. If you wish to
>> talk
>>> on this issue. Contact me direct. Not on the net. Or 319-521=4891 Cell.
>>> Bob Dunahugh
>>> 78 Royale since 2003
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>>
>>
>>
>> --
>> Jim Kanomata
>> Applied/GMC, Newark,CA
>> jimk@appliedairfilters.com
>> http://www.gmcrvparts.com
>> 1-800-752-7502
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
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| [GMCnet] Re: Good engine destroyed. Yours could be next. [message #363876 is a reply to message #363875] |
Sat, 08 May 2021 14:25 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
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The Howell comes with one 02 Sensor. But it also comes with the EBL that
opens up a whole new world of tuning possibilities. While nothing is the
Ideal setup, and the intake manifold has a block off plate to allow the 2
barrel Howell throttle body to adapt to the quadrajet 4 barrel intake
manifold is not ideal either.
A whole new plenum type manifold that only had to flow air, with
individual port injectors would seem at first glance to be the real "Cats
Meow" for fuel injection. But, if one or more injectors fail to meter
correctly, they can and do cook individual cylinders. There is plenty of
examples of that happening, too.
As is often said "Taint nuthin' perfect". Same is true with any
mechanical device. STUFF HAPPENS.
Jim Hupy
Salem, Oregon
On Sat, May 8, 2021 at 11:23 AM Zandr Milewski wrote:
> So, given that failure mode, does the Howell have two O2 sensors, one
> per bank?
>
> On 5/8/21 09:33, James Hupy wrote:
>> The stock GMC intake manifold is a split flow design. One side (a Primary
>> and Secondary) of a quadrajet carb feeds 2 cylinders on each side of the
>> engine, and the other side (Primary and Secondary) of the quadrajet feeds
>> the remaining 4 cylinders (2 on each side) of the 455.
>> So, in a perfect world where the quadrajet is working as the
> factory
>> designed it to do, all 8 cylinders receive a correct amount of air/fuel
>> mixture.
>> BUT, when the quadrajet is NOT working as designed, (like happens
>> when well intentioned but uninformed tweakers mess with jets and needles
> in
>> an attempt to improve their fuel economy, for example), it is easy for 4
>> cylinders to go very lean, and toast the whole engine.
>> Jim Hupy
>> Salem, Oregon
>>
>>
>> On Sat, May 8, 2021, 8:13 AM Jim Kanomata wrote:
>>
>>> Bob,
>>> So what did the carb do that trashed the engine???
>>>
>>> On Sat, May 8, 2021 at 7:44 AM Bob Dunahugh
> wrote:
>>>
>>>> I got a call from someone today. That severally damaged a real good
>>>> running 455. That I built for him 2 years ago. That engine is now
> trash.
>>>> When the engine was going in. I pleaded with him to put a GM/Howel EFI
>>>> system in. His response was. " My carb works great. It's been working
> to
>>>> perfection. The carb was rebuilt last year. By someone that knows them
>>>> well." I should keep my mouth shut on this. As I could go on for days.
>>>> Over engines. On ways to extend your engines service life. But I'm just
>>>> sick of this happening. I now know of 4 good engines destroyed in this
>>>> manner. In the last few years. Engines are my thing. I could post a
> lot
>>> on
>>>> engines. But it's best that I not. I push GM engines way past their
>>> design
>>>> paramotors. And don't destroy them.
>>>>
>>>> Sorry. I digress. That stock Q jet has always been considered
> to be
>>>> one of the finest carbs ever built. As to controlling the air/fuel
>>> ratios.
>>>> Over its entire operating range.
>>>> The general though. Is that the carb dumps an air/fuel mixture
> into
>>>> an open chamber. That's in the intake manifold. Well. Not really.
> The Q
>>>> jet that came on the GMC. Are really two carbs in one aluminum casting.
>>>> Thus. The left carb feeds 2 cylinders on each side of the engine. The
>>> right
>>>> side feeds the other remaining 4 cylinders.
>>>> The problem is that if one side of the carb goes lean. And starts
>>>> burning up its 4 cylinders. You'll have absolutely no idea of the in
>>>> pending destruction. Till it's just too late. With the GM/Howell
> system.
>>>> The engine check light will come on. To let you know of any issues.
> Then
>>>> tell you what's wrong.
>>>> Engine service life before the mid 80's was under 100,000 miles.
> Then
>>>> in the late 80's. EFI came along. Then service life more than doubled.
>>>> Yes. Other things that helped. But EFI was the BIGGY. If you wish to
>>> talk
>>>> on this issue. Contact me direct. Not on the net. Or 319-521=4891 Cell.
>>>> Bob Dunahugh
>>>> 78 Royale since 2003
>>>>
>>>> _______________________________________________
>>>> GMCnet mailing list
>>>> Unsubscribe or Change List Options:
>>>>
>>>
>>>
>>> --
>>> Jim Kanomata
>>> Applied/GMC, Newark,CA
>>> jimk@appliedairfilters.com
>>> http://www.gmcrvparts.com
>>> 1-800-752-7502
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
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| [GMCnet] Re: Good engine destroyed. Yours could be next. [message #363878 is a reply to message #363871] |
Sat, 08 May 2021 17:06 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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Senior Member |
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I'm one of the unfortunate ones who lost a great rebuilt 403 after only 5,000 miles. Q-Jet which was rebuilt by an expert several years earlier malfunctioned, took the A/F ratio to 19! Burned a huge hole in #8 piston. I had another engine rebuilt and decided to have it dyno'd, that's when they discovered the bad carb. If I wouldn't have had it dyno'd, I'd have put the carb on the new engine and probably smoked another one. Instead I put on a Holley Sniper Quadrajet EFI system along with the matching Holley Hyperspark Distributor/Ignition system. Engine runs absolutely awesome. Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Bob Dunahugh Date: 5/8/21 9:44 AM (GMT-06:00) To: gmclist@list.gmcnet.org Subject: [GMCnet] Good engine destroyed. Yours could be next. I got a call from someone today. That severally damaged a real good running 455. That I built for him 2 years ago. That engine is now trash. When the engine was going in. I pleaded with him to put a GM/Howel EFI system in. His response was. " My carb works great. It's been working to perfection. The carb was rebuilt last year. By someone that knows them well." I should keep my mouth shut on this. As I could go on for days. Over engines. On ways to extend your engines service life. But I'm just sick of this happening. I now know of 4 good engines destroyed in this manner. In the last few years. Engines are my thing. I could post a lot on engines. But it's best that I not. I push GM engines way past their design paramotors. And don't destroy them. Sorry. I digress. That stock Q jet has always been considered to be one of the finest carbs ever built. As to controlling the air/fuel ratios. Over its entire operating range. The general though. Is that the carb dumps an air/fuel mixture into an open chamber. That's in the intake manifold. Well. Not really. The Q jet that came on the GMC. Are really two carbs in one aluminum casting. Thus. The left carb feeds 2 cylinders on each side of the engine. The right side feeds the other remaining 4 cylinders. The problem is that if one side of the carb goes lean. And starts burning up its 4 cylinders. You'll have absolutely no idea of the in pending destruction. Till it's just too late. With the GM/Howell system. The engine check light will come on. To let you know of any issues. Then tell you what's wrong. Engine service life before the mid 80's was under 100,000 miles. Then in the late 80's. EFI came along. Then service life more than doubled. Yes. Other things that helped. But EFI was the BIGGY. If you wish to talk on this issue. Contact me direct. Not on the net. Or 319-521=4891 Cell.Bob Dunahugh78 Royale since 2003_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Re: Good engine destroyed. Yours could be next. [message #363880 is a reply to message #363875] |
Sat, 08 May 2021 19:21 |
cadelec
Messages: 303
Registered: September 2011
Location: Brisbane Australia
Karma: 1
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Senior Member |
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My throttle body system has one O2 sensor on the left hand side. I assume from the info above that each injector feeds 2 cylinders on each side so therefore we only need to monitor the O2 on one bank to gauge the ratio of fuel.
Trevor
Brisbane Australia
Siesta Koala 76 Edgemont (old Bobby Moores)
71 Cadillac Eldo Convert
58 Cadillac Eldorado Brougham Project
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| Re: [GMCnet] EFI systems out there. Are NOT all the same. [message #363896 is a reply to message #363893] |
Sun, 09 May 2021 07:15 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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I do agree with bob. However the howell and ebl
Sytems are obd1. I doubt most parts stores can read obd1.
However, diy, it is very easy to read the code. Ebl you hook to laptop.
Or you pull up the instructions on use a paperclip and read the blinks of the check engine light.
It does normally run just one o2 on the driver side bank. But the ebl has ability to have a wide band o2 watching both, and display live time on laptop. The gm based efi was also the only one running a knock sensor.
One of the reasons i installed efi on my rebuilt motor was to help insure not only the investment of the engine, but some piece of mind.
Either way, efi seems pretty nice. If i was
Stuck on a carb, a wide band o2 can easily be added.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] Good engine destroyed. Yours could be next. [message #363899 is a reply to message #363871] |
Sun, 09 May 2021 07:53 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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My coach has an Atomic MSD fitted (It was a California coach), and has 2 O2 sensors. Left bank feeds the MSD, right bank feeds gauge. It has many modes, I leave in in ratio mode. If I ever saw it go over 15 - 1 or so, I'd find out why (It hasn't).
--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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