Home » Public Forums » GMCnet » [GMCnet] Last weekend was a Hugh change in driving my GMC.
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| Re: [GMCnet] Last weekend was a Hugh change in driving my GMC. [message #279480 is a reply to message #279471] |
Wed, 10 June 2015 05:33   |
Joe Weir
Messages: 769
Registered: February 2013
Location: Columbia, SC
Karma: 7
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Senior Member |
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Had a little pep to it?
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
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| Re: [GMCnet] Last weekend was a Hugh change in driving my GMC. [message #279498 is a reply to message #279471] |
Wed, 10 June 2015 09:00 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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I had the opposite experience driving some of that same stretch of road you probably traveled. Last weekend was my second time towing the jeep wrangler, and on I-35 between faribault and I-494 when encountering those long hills. I actually got passed!
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] Last weekend was a Hugh change in driving my GMC. [message #279539 is a reply to message #279471] |
Wed, 10 June 2015 17:55 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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My '78 Royale (403 with 3.42 gears, Holley carb and Thorley headers) pulls just fine, but being a carburetor motor, it runs out of steam at high altitude. I just (!) got back from five days at the Grand Canyon, and did lots of 5-6% hills at 6-7500 feet. Can't say I'm setting any land speed records though I do go around the loaded semis pretty well. But mainly, I'm just looking forward to installing the Howell TB fuel injection system I've had sitting around for over a year now... I'm betting that's going to help make it possible to tow my '96 Jeep Cherokee XJ 4x4 up those hills without embarrassing myself TOO much.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Last weekend was a Hugh change in driving my GMC. [message #279542 is a reply to message #279539] |
Wed, 10 June 2015 18:46 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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habbyguy wrote on Wed, 10 June 2015 15:55My '78 Royale (403 with 3.42 gears, Holley carb and Thorley headers) pulls just fine, but being a carburetor motor, it runs out of steam at high altitude. I just (!) got back from five days at the Grand Canyon, and did lots of 5-6% hills at 6-7500 feet. Can't say I'm setting any land speed records though I do go around the loaded semis pretty well. But mainly, I'm just looking forward to installing the Howell TB fuel injection system I've had sitting around for over a year now... I'm betting that's going to help make it possible to tow my '96 Jeep Cherokee XJ 4x4 up those hills without embarrassing myself TOO much.
I don't know if you will be able to go much faster, but they sure start great at 7,000 feet. The EFI runs out of steam a bit because the engine just can't breath. Of course when I walk fast up a hill at 7,000, I don't do so well either. Hmmm... if I had a Kompressor on the GMC.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Last weekend was a Hugh change in driving my GMC. [message #279545 is a reply to message #279542] |
Wed, 10 June 2015 18:58 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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One thing that you might take into consideration is that a quadrajet has
four bores to breathe through, and a throttle body efi like the Howell
system only have 2. At wide open throttle, more air flows through the carb.
But on the other hand, the efi computer does a much better job of adjusting
for altitude. So, at lower altitudes, a properly set up carb will
outperform an efi. Not so at 6000+ feet. Kinda, darned if you do, darned if
you don't.
Jim Hupy
Salem, Oregon
78 GMC ROYALE 403
On Jun 10, 2015 4:47 PM, "George Beckman" wrote:
> habbyguy wrote on Wed, 10 June 2015 15:55
>> My '78 Royale (403 with 3.42 gears, Holley carb and Thorley headers)
> pulls just fine, but being a carburetor motor, it runs out of steam at high
>> altitude. I just (!) got back from five days at the Grand Canyon, and
> did lots of 5-6% hills at 6-7500 feet. Can't say I'm setting any land speed
>> records though I do go around the loaded semis pretty well. But mainly,
> I'm just looking forward to installing the Howell TB fuel injection system
>> I've had sitting around for over a year now... I'm betting that's going
> to help make it possible to tow my '96 Jeep Cherokee XJ 4x4 up those hills
>> without embarrassing myself TOO much.
>
>
> I don't know if you will be able to go much faster, but they sure start
> great at 7,000 feet. The EFI runs out of steam a bit because the engine just
> can't breath. Of course when I walk fast up a hill at 7,000, I don't do so
> well either. Hmmm... if I had a Kompressor on the GMC.
> --
> '74 Eleganza, SE, Howell + EBL
> Best Wishes,
> George
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| Re: [GMCnet] Last weekend was a Hugh change in driving my GMC. [message #279556 is a reply to message #279545] |
Wed, 10 June 2015 19:40 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Senior Member |
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James Hupy wrote on Wed, 10 June 2015 16:58One thing that you might take into consideration is that a quadrajet has
four bores to breathe through, and a throttle body efi like the Howell
system only have 2. At wide open throttle, more air flows through the carb.
But on the other hand, the efi computer does a much better job of adjusting
for altitude. So, at lower altitudes, a properly set up carb will
outperform an efi. Not so at 6000+ feet. Kinda, darned if you do, darned if
you don't.
Jim, yeah - I'm pretty much living the "darned if you do, darned if you don't lifestyle"... 
I'm really happy with the performance of my coach at low altitude, plus the throttle body I got used to feed a big block Chevy, so I suspect it'll be up to the task of keeping my 403 breathing right. I still have about 10,000 decisions to make when it comes to installing and configuring the fuel injection system, but my main concern will be to improve high altitude performance (since at least half my trips involve a climb to at least 7,000 feet), and then I'll go off in pursuit of better low altitude performance... and of course, 12mpg.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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