Home » Public Forums » GMCnet » [GMCnet] Injection versus Carbs
| Re: [GMCnet] Injection versus Carbs [message #74184 is a reply to message #74176] |
Wed, 17 February 2010 17:57   |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Senior Member |
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Mike,
Larry W. must be off line while travelling or he'd have chimed in: He got
all excited about an altitude compensated Quadrajet he came across. He
spent a lot of time and his expertise on getting it working -- for a while.
From what I recall of what he told me, it worked great as long as he kept
working on it. As if the QJ's not complicated enough, imagine what those
extra bellows, jets, needles, etc., would add. I don't remember whether
he's running it right now -- I don't think so -- but I do know he's planning
on port injecting his Cad 500 ASAP.
Ken H.
Americus, GA
'76 X-Birchaven
www.gmcwipersetc.com
On Wed, Feb 17, 2010 at 6:34 PM, Matt Colie <mcolie@chartermi.net> wrote:
>
>
> mlincoln wrote on Mon, 15 February 2010 16:31
> > Does anyone have actual experience with "splitting the difference" in the
> Quadrajet enrichment to suit a MSL of 4500 to 5000 feet? I was once told
> that some old Detroit iron came with a "high altitude option" (possibly a
> re-metered carb?). A shop in ...
>
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| Re: [GMCnet] Injection versus Carbs [message #74194 is a reply to message #74184] |
Wed, 17 February 2010 19:31 |
mlincoln
Messages: 107
Registered: August 2006
Location: Salt Lake City
Karma: 0
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Has anyone tried a carb (a fixed carb, not an altitude-adjusting one) that has been specifically leaned for altitude? Does it detonate (too lean) at sea level? I'm thinking that one of the experienced tinkerers might know.
In airplane flying in the Rockies one leans to peak rpm (fixed pitch prop), then richens to make the exhaust gas temp 50-100 degrees cooler for takeoff. There's a big difference in power: running full rich (firewalled mixture control) compared to optimally leaned makes a huge difference in a high density-altitude situation. In the Utah mountains I once foolishly filled up a Cessna 152 (a little underpowered straight-tailed 152 from the 1950's) with avgas the night before, and then took off the next day. My friend and I flew the plane in ground effect for three miles to the edge of Bryce Canyon (airport was 9000 MSL), in order to throw ourselves off the edge and get some altitude beneath us. If I hadn't leaned for altitude I'm sure we would never have even gotten into ground effect. (By the time we got to the Grand Canyon 45 min later, I had thermaled to 14,500 feet, and LA Center didn't believe our type aircraft--an 89 hp 152--given our altitude-encoding transponder rea
ding, but that's what rising air will do for you).
Therefore I suspect an optimal air *mass* to fuel mixture might make a significant difference in the GMC too. But, without the manual mixture control, it may be that the altered air/fuel volumetric mixture of the "mountain carb", when running at low altitude with the air mass much greater, would result in a too lean situation, with unacceptable detonation or at least higher cylinder head/EGT and wear in the valve train.
Has anyone tried it?
Mike
On Feb 17, 2010, at 6:57 PM, Ken Henderson wrote:
> Mike,
>
> Larry W. must be off line while travelling or he'd have chimed in: He got
> all excited about an altitude compensated Quadrajet he came across. He
> spent a lot of time and his expertise on getting it working -- for a while.
> From what I recall of what he told me, it worked great as long as he kept
> working on it. As if the QJ's not complicated enough, imagine what those
> extra bellows, jets, needles, etc., would add. I don't remember whether
> he's running it right now -- I don't think so -- but I do know he's planning
> on port injecting his Cad 500 ASAP.
>
> Ken H.
> Americus, GA
> '76 X-Birchaven
> www.gmcwipersetc.com
>
>
> On Wed, Feb 17, 2010 at 6:34 PM, Matt Colie <mcolie@chartermi.net> wrote:
>
>>
>>
>> mlincoln wrote on Mon, 15 February 2010 16:31
>>> Does anyone have actual experience with "splitting the difference" in the
>> Quadrajet enrichment to suit a MSL of 4500 to 5000 feet? I was once told
>> that some old Detroit iron came with a "high altitude option" (possibly a
>> re-metered carb?). A shop in ...
>>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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Mike
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| Re: [GMCnet] Injection versus Carbs [message #74201 is a reply to message #74194] |
Wed, 17 February 2010 20:23 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| mlincoln wrote on Wed, 17 February 2010 19:31 |
Has anyone tried a carb (a fixed carb, not an altitude-adjusting one) that has been specifically leaned for altitude? Does it detonate (too lean) at sea level? I'm thinking that one of the experienced tinkerers might know.
In airplane flying in the Rockies one leans to peak rpm (fixed pitch prop), then richens to make the exhaust gas temp 50-100 degrees cooler for takeoff. There's a big difference in power: running full rich (firewalled mixture control) compared to optimally leaned makes a huge difference in a high density-altitude situation. In the Utah mountains I once foolishly filled up a Cessna 152 (a little underpowered straight-tailed 152 from the 1950's) with avgas the night before, and then took off the next day. My friend and I flew the plane in ground effect for three miles to the edge of Bryce Canyon (airport was 9000 MSL), in order to throw ourselves off the edge and get some altitude beneath us. If I hadn't leaned for altitude I'm sure we would never have even gotten into ground effect. (By the time we got to the Grand Canyon 45 min later, I had thermaled to 14,500 feet, and LA Center didn't believe our type aircraft--an 89 hp 152--given our altitude-encoding transponder rea
ding, but that's what rising air will do for you).
Therefore I suspect an optimal air *mass* to fuel mixture might make a significant difference in the GMC too. But, without the manual mixture control, it may be that the altered air/fuel volumetric mixture of the "mountain carb", when running at low altitude with the air mass much greater, would result in a too lean situation, with unacceptable detonation or at least higher cylinder head/EGT and wear in the valve train.
Has anyone tried it?
Mike
|
I had a similar experience on my way to Alaska coming out of a hot Montana airport fully loaded with fuel, passengers, and camping gear. I could not clear the power lines 2 miles off of the end of the runway. I thought about going under them. Then it occurred to me to just turn left or right and I won't have to go over them. It took quite a while to get up to cruising altitude that day.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Injection versus Carbs [message #74205 is a reply to message #74184] |
Wed, 17 February 2010 20:57 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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Could I add that in 1975, Cadillac started the year out with an
altitude
compensated Q-Jet. It was very complicated, with two power
pistons.
three metering rods, and an aneroid-controlled jet. In the
middle of
the year, probably when they came out with EFI, they switched
back
to a standard Q-Jet. Then, in 1976-7-8, they re-introduced the
aneroid as an "altitude option". I have both of the 75 model
carbs,
and I ran out of patience screwing with the trick one. JWID
Gary Kosier
----- Original Message -----
From: "Ken Henderson" <ken0henderson@gmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Wednesday, February 17, 2010 6:57 PM
Subject: Re: [GMCnet] Injection versus Carbs
> Mike,
>
> Larry W. must be off line while travelling or he'd have chimed
> in: He got
> all excited about an altitude compensated Quadrajet he came
> across. He
> spent a lot of time and his expertise on getting it working --
> for a while.
> From what I recall of what he told me, it worked great as long
> as he kept
> working on it. As if the QJ's not complicated enough, imagine
> what those
> extra bellows, jets, needles, etc., would add. I don't
> remember whether
> he's running it right now -- I don't think so -- but I do know
> he's planning
> on port injecting his Cad 500 ASAP.
>
> Ken H.
> Americus, GA
> '76 X-Birchaven
> www.gmcwipersetc.com
>
>
> On Wed, Feb 17, 2010 at 6:34 PM, Matt Colie
> <mcolie@chartermi.net> wrote:
>
>>
>>
>> mlincoln wrote on Mon, 15 February 2010 16:31
>> > Does anyone have actual experience with "splitting the
>> > difference" in the
>> Quadrajet enrichment to suit a MSL of 4500 to 5000 feet? I
>> was once told
>> that some old Detroit iron came with a "high altitude option"
>> (possibly a
>> re-metered carb?). A shop in ...
>>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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| Re: [GMCnet] Injection versus Carbs [message #74212 is a reply to message #74194] |
Wed, 17 February 2010 21:46 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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Mike,
On the late Q-Jets, there is an adjustable part throttle screw,
which regulates the height of the primary needles in the jet.
Directly above it is an aluminum plug. Knock the plug out and
tap the hole for 3/8" thread. put a short socket head
set-screw in it. Take a fairly long 5/16" bolt, cut the threads
off and slot the end. To change the mixture, you have to
stop, raise the engine lid, remove the bonnet from the carb,
remove the set screw and adjust the APT screw. Not as easy
as leaning the mixture on a plane, but you can't pull the plane
to the side of the road and shut it off. Works for me!
Gary Kosier
77EII & 77PB
Newark, Ohio
----- Origial Message -----
From: "Michael Lincoln" <mlincoln1@gmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Wednesday, February 17, 2010 8:31 PM
Subject: Re: [GMCnet] Injection versus Carbs
> Has anyone tried a carb (a fixed carb, not an
> altitude-adjusting one) that has been specifically leaned for
> altitude? Does it detonate (too lean) at sea level? I'm
> thinking that one of the experienced tinkerers might know.
>
> In airplane flying in the Rockies one leans to peak rpm (fixed
> pitch prop), then richens to make the exhaust gas temp 50-100
> degrees cooler for takeoff. There's a big difference in power:
> running full rich (firewalled mixture control) compared to
> optimally leaned makes a huge difference in a high
> density-altitude situation. In the Utah mountains I once
> foolishly filled up a Cessna 152 (a little underpowered
> straight-tailed 152 from the 1950's) with avgas the night
> before, and then took off the next day. My friend and I flew
> the plane in ground effect for three miles to the edge of Bryce
> Canyon (airport was 9000 MSL), in order to throw ourselves off
> the edge and get some altitude beneath us. If I hadn't leaned
> for altitude I'm sure we would never have even gotten into
> ground effect. (By the time we got to the Grand Canyon 45 min
> later, I had thermaled to 14,500 feet, and LA Center didn't
> believe our type aircraft--an 89 hp 152--given our
> altitude-encoding transponder rea
> ding, but that's what rising air will do for you).
>
> Therefore I suspect an optimal air *mass* to fuel mixture might
> make a significant difference in the GMC too. But, without the
> manual mixture control, it may be that the altered air/fuel
> volumetric mixture of the "mountain carb", when running at low
> altitude with the air mass much greater, would result in a too
> lean situation, with unacceptable detonation or at least higher
> cylinder head/EGT and wear in the valve train.
>
> Has anyone tried it?
>
> Mike
>
>
> On Feb 17, 2010, at 6:57 PM, Ken Henderson wrote:
>
>> Mike,
>>
>> Larry W. must be off line while travelling or he'd have chimed
>> in: He got
>> all excited about an altitude compensated Quadrajet he came
>> across. He
>> spent a lot of time and his expertise on getting it working --
>> for a while.
>> From what I recall of what he told me, it worked great as long
>> as he kept
>> working on it. As if the QJ's not complicated enough, imagine
>> what those
>> extra bellows, jets, needles, etc., would add. I don't
>> remember whether
>> he's running it right now -- I don't think so -- but I do know
>> he's planning
>> on port injecting his Cad 500 ASAP.
>>
>> Ken H.
>> Americus, GA
>> '76 X-Birchaven
>> www.gmcwipersetc.com
>>
>>
>> On Wed, Feb 17, 2010 at 6:34 PM, Matt Colie
>> <mcolie@chartermi.net> wrote:
>>
>>>
>>>
>>> mlincoln wrote on Mon, 15 February 2010 16:31
>>>> Does anyone have actual experience with "splitting the
>>>> difference" in the
>>> Quadrajet enrichment to suit a MSL of 4500 to 5000 feet? I
>>> was once told
>>> that some old Detroit iron came with a "high altitude option"
>>> (possibly a
>>> re-metered carb?). A shop in ...
>>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Injection versus Carbs [message #74215 is a reply to message #74212] |
Wed, 17 February 2010 22:01 |
mlincoln
Messages: 107
Registered: August 2006
Location: Salt Lake City
Karma: 0
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Senior Member |
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Now that's what I've been looking for...do you have any pictures of this modification, Gary? Do you know if this works on the quadrajets fitted to the 403s?
I need to get my carburetor rebuilt...I wonder if this fellow Dick Patterson can do what you describe.
Best, Mike
Born a Buckeye, but went to U of Mich, normally living in Utah
1978 Royale
On Feb 17, 2010, at 10:46 PM, Kosier wrote:
> Mike,
>
> On the late Q-Jets, there is an adjustable part throttle screw,
> which regulates the height of the primary needles in the jet.
> Directly above it is an aluminum plug. Knock the plug out and
> tap the hole for 3/8" thread. put a short socket head
> set-screw in it. Take a fairly long 5/16" bolt, cut the threads
> off and slot the end. To change the mixture, you have to
> stop, raise the engine lid, remove the bonnet from the carb,
> remove the set screw and adjust the APT screw. Not as easy
> as leaning the mixture on a plane, but you can't pull the plane
> to the side of the road and shut it off. Works for me!
>
> Gary Kosier
> 77EII & 77PB
> Newark, Ohio
>
> ----- Origial Message -----
> From: "Michael Lincoln" <mlincoln1@gmail.com>
> To: <gmclist@temp.gmcnet.org>
> Sent: Wednesday, February 17, 2010 8:31 PM
> Subject: Re: [GMCnet] Injection versus Carbs
>
>
>> Has anyone tried a carb (a fixed carb, not an
>> altitude-adjusting one) that has been specifically leaned for
>> altitude? Does it detonate (too lean) at sea level? I'm
>> thinking that one of the experienced tinkerers might know.
>>
>> In airplane flying in the Rockies one leans to peak rpm (fixed
>> pitch prop), then richens to make the exhaust gas temp 50-100
>> degrees cooler for takeoff. There's a big difference in power:
>> running full rich (firewalled mixture control) compared to
>> optimally leaned makes a huge difference in a high
>> density-altitude situation. In the Utah mountains I once
>> foolishly filled up a Cessna 152 (a little underpowered
>> straight-tailed 152 from the 1950's) with avgas the night
>> before, and then took off the next day. My friend and I flew
>> the plane in ground effect for three miles to the edge of Bryce
>> Canyon (airport was 9000 MSL), in order to throw ourselves off
>> the edge and get some altitude beneath us. If I hadn't leaned
>> for altitude I'm sure we would never have even gotten into
>> ground effect. (By the time we got to the Grand Canyon 45 min
>> later, I had thermaled to 14,500 feet, and LA Center didn't
>> believe our type aircraft--an 89 hp 152--given our
>> altitude-encoding transponder rea
>> ding, but that's what rising air will do for you).
>>
>> Therefore I suspect an optimal air *mass* to fuel mixture might
>> make a significant difference in the GMC too. But, without the
>> manual mixture control, it may be that the altered air/fuel
>> volumetric mixture of the "mountain carb", when running at low
>> altitude with the air mass much greater, would result in a too
>> lean situation, with unacceptable detonation or at least higher
>> cylinder head/EGT and wear in the valve train.
>>
>> Has anyone tried it?
>>
>> Mike
>>
>>
>> On Feb 17, 2010, at 6:57 PM, Ken Henderson wrote:
>>
>>> Mike,
>>>
>>> Larry W. must be off line while travelling or he'd have chimed
>>> in: He got
>>> all excited about an altitude compensated Quadrajet he came
>>> across. He
>>> spent a lot of time and his expertise on getting it working --
>>> for a while.
>>> From what I recall of what he told me, it worked great as long
>>> as he kept
>>> working on it. As if the QJ's not complicated enough, imagine
>>> what those
>>> extra bellows, jets, needles, etc., would add. I don't
>>> remember whether
>>> he's running it right now -- I don't think so -- but I do know
>>> he's planning
>>> on port injecting his Cad 500 ASAP.
>>>
>>> Ken H.
>>> Americus, GA
>>> '76 X-Birchaven
>>> www.gmcwipersetc.com
>>>
>>>
>>> On Wed, Feb 17, 2010 at 6:34 PM, Matt Colie
>>> <mcolie@chartermi.net> wrote:
>>>
>>>>
>>>>
>>>> mlincoln wrote on Mon, 15 February 2010 16:31
>>>>> Does anyone have actual experience with "splitting the
>>>>> difference" in the
>>>> Quadrajet enrichment to suit a MSL of 4500 to 5000 feet? I
>>>> was once told
>>>> that some old Detroit iron came with a "high altitude option"
>>>> (possibly a
>>>> re-metered carb?). A shop in ...
>>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> List Information and Subscription Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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Mike
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| Re: [GMCnet] Injection versus Carbs [message #74217 is a reply to message #74215] |
Wed, 17 February 2010 22:34 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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Ummmmm..... I think Dick would frown on people getting their
little fingers into his carb rebuild jobs, I got my info from
Cliff Ruggles, who wrote the latest book on Q-Jets. He's only
about 30 miles north of me, so I just go up to see him for
info and parts. He's a drag racer, so he knows about modifying
Q-Jets.
I think all 76 and later carbs are built this way. Look under
the air cleaner gasket dead center in the front for a round plug
of aluminum. I never took any pictures cause I wasn't sure of
what I was doing.
Gary
----- Original Message -----
From: "Michael Lincoln" <mlincoln1@gmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Wednesday, February 17, 2010 11:01 PM
Subject: Re: [GMCnet] Injection versus Carbs
> Now that's what I've been looking for...do you have any
> pictures of this modification, Gary? Do you know if this works
> on the quadrajets fitted to the 403s?
>
> I need to get my carburetor rebuilt...I wonder if this fellow
> Dick Patterson can do what you describe.
>
> Best, Mike
> Born a Buckeye, but went to U of Mich, normally living in Utah
> 1978 Royale
>
>
> On Feb 17, 2010, at 10:46 PM, Kosier wrote:
>
>> Mike,
>>
>> On the late Q-Jets, there is an adjustable part throttle
>> screw,
>> which regulates the height of the primary needles in the jet.
>> Directly above it is an aluminum plug. Knock the plug out and
>> tap the hole for 3/8" thread. put a short socket head
>> set-screw in it. Take a fairly long 5/16" bolt, cut the
>> threads
>> off and slot the end. To change the mixture, you have to
>> stop, raise the engine lid, remove the bonnet from the carb,
>> remove the set screw and adjust the APT screw. Not as easy
>> as leaning the mixture on a plane, but you can't pull the
>> plane
>> to the side of the road and shut it off. Works for me!
>>
>> Gary Kosier
>> 77EII & 77PB
>> Newark, Ohio
>>
>> ----- Origial Message -----
>> From: "Michael Lincoln" <mlincoln1@gmail.com>
>> To: <gmclist@temp.gmcnet.org>
>> Sent: Wednesday, February 17, 2010 8:31 PM
>> Subject: Re: [GMCnet] Injection versus Carbs
>>
>>
>>> Has anyone tried a carb (a fixed carb, not an
>>> altitude-adjusting one) that has been specifically leaned for
>>> altitude? Does it detonate (too lean) at sea level? I'm
>>> thinking that one of the experienced tinkerers might know.
>>>
>>> In airplane flying in the Rockies one leans to peak rpm
>>> (fixed
>>> pitch prop), then richens to make the exhaust gas temp 50-100
>>> degrees cooler for takeoff. There's a big difference in
>>> power:
>>> running full rich (firewalled mixture control) compared to
>>> optimally leaned makes a huge difference in a high
>>> density-altitude situation. In the Utah mountains I once
>>> foolishly filled up a Cessna 152 (a little underpowered
>>> straight-tailed 152 from the 1950's) with avgas the night
>>> before, and then took off the next day. My friend and I flew
>>> the plane in ground effect for three miles to the edge of
>>> Bryce
>>> Canyon (airport was 9000 MSL), in order to throw ourselves
>>> off
>>> the edge and get some altitude beneath us. If I hadn't
>>> leaned
>>> for altitude I'm sure we would never have even gotten into
>>> ground effect. (By the time we got to the Grand Canyon 45
>>> min
>>> later, I had thermaled to 14,500 feet, and LA Center didn't
>>> believe our type aircraft--an 89 hp 152--given our
>>> altitude-encoding transponder rea
>>> ding, but that's what rising air will do for you).
>>>
>>> Therefore I suspect an optimal air *mass* to fuel mixture
>>> might
>>> make a significant difference in the GMC too. But, without
>>> the
>>> manual mixture control, it may be that the altered air/fuel
>>> volumetric mixture of the "mountain carb", when running at
>>> low
>>> altitude with the air mass much greater, would result in a
>>> too
>>> lean situation, with unacceptable detonation or at least
>>> higher
>>> cylinder head/EGT and wear in the valve train.
>>>
>>> Has anyone tried it?
>>>
>>> Mike
>>>
>>>
>>> On Feb 17, 2010, at 6:57 PM, Ken Henderson wrote:
>>>
>>>> Mike,
>>>>
>>>> Larry W. must be off line while travelling or he'd have
>>>> chimed
>>>> in: He got
>>>> all excited about an altitude compensated Quadrajet he came
>>>> across. He
>>>> spent a lot of time and his expertise on getting it
>>>> working --
>>>> for a while.
>>>> From what I recall of what he told me, it worked great as
>>>> long
>>>> as he kept
>>>> working on it. As if the QJ's not complicated enough,
>>>> imagine
>>>> what those
>>>> extra bellows, jets, needles, etc., would add. I don't
>>>> remember whether
>>>> he's running it right now -- I don't think so -- but I do
>>>> know
>>>> he's planning
>>>> on port injecting his Cad 500 ASAP.
>>>>
>>>> Ken H.
>>>> Americus, GA
>>>> '76 X-Birchaven
>>>> www.gmcwipersetc.com
>>>>
>>>>
>>>> On Wed, Feb 17, 2010 at 6:34 PM, Matt Colie
>>>> <mcolie@chartermi.net> wrote:
>>>>
>>>>>
>>>>>
>>>>> mlincoln wrote on Mon, 15 February 2010 16:31
>>>>>> Does anyone have actual experience with "splitting the
>>>>>> difference" in the
>>>>> Quadrajet enrichment to suit a MSL of 4500 to 5000 feet? I
>>>>> was once told
>>>>> that some old Detroit iron came with a "high altitude
>>>>> option"
>>>>> (possibly a
>>>>> re-metered carb?). A shop in ...
>>>>>
>>>> _______________________________________________
>>>> GMCnet mailing list
>>>> List Information and Subscription Options:
>>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> List Information and Subscription Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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| Re: [GMCnet] Injection versus Carbs [message #74232 is a reply to message #73285] |
Thu, 18 February 2010 09:06 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
|
|
I was just reading your comments about how you have never tracked your mileage on the GMC, I must say I have let they go by as well it has been such a hassle.
I had a friend travel with me last time and he tried to track it. If his math was correct I may have an idea but who knows.
I have created a spread sheet for tracking mileage on an excel program.
I am pretty good with the formulas in excel so I tend to add more as I think of it.
All you would add is the date, present mileage and cost.
If you add just the present mileage, such as on the road in travel mode, it estimates mileage driven and mileage left.
The program will tell you your MPG, estimated miles per tank, how many miles you drove and how many miles are left, estimate of fuel left in the tank. It also gives an average of your MPG, Cost per fill and average cost. Yeah, sometimes I think I have too much time, HA!! Like that can happen...
It has a provision to account for the reserve gallons or just leave it out.
Truely an experiment in playing with numbers and if you are good with the formulas, you can tweek it as well.
If anyone would be interested in this program I could email it to you and you could play with it.
It is not much less clumbsy than writing the info on paper, but it is more fun and does all the computing.
If this can be helpful to you, let me know. I still update things and if you have any ideas to add, we could try that too.
Just a thought
LarC ( Always interested in numbers and would like to see the GMC numbers much higher - HAH! )
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
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| Re: [GMCnet] Injection versus Carbs [message #74233 is a reply to message #74215] |
Thu, 18 February 2010 09:09 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
|
Senior Member |
|
|
Michael,
I think someone covered this but I rely upon people who understand carbs fully to do my work. I know the peramaters I want them to perform in and they take it from there. Springfield does a good job and Dick really understand the Qjet. If you want one rebuilt, he is a good choice.
Jim Bounds
----------------------------
----- Original Message ----
From: Michael Lincoln <mlincoln1@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Wed, February 17, 2010 11:01:13 PM
Subject: Re: [GMCnet] Injection versus Carbs
Now that's what I've been looking for...do you have any pictures of this modification, Gary? Do you know if this works on the quadrajets fitted to the 403s?
I need to get my carburetor rebuilt...I wonder if this fellow Dick Patterson can do what you describe.
Best, Mike
Born a Buckeye, but went to U of Mich, normally living in Utah
1978 Royale
On Feb 17, 2010, at 10:46 PM, Kosier wrote:
> Mike,
>
> On the late Q-Jets, there is an adjustable part throttle screw,
> which regulates the height of the primary needles in the jet.
> Directly above it is an aluminum plug. Knock the plug out and
> tap the hole for 3/8" thread. put a short socket head
> set-screw in it. Take a fairly long 5/16" bolt, cut the threads
> off and slot the end. To change the mixture, you have to
> stop, raise the engine lid, remove the bonnet from the carb,
> remove the set screw and adjust the APT screw. Not as easy
> as leaning the mixture on a plane, but you can't pull the plane
> to the side of the road and shut it off. Works for me!
>
> Gary Kosier
> 77EII & 77PB
> Newark, Ohio
>
> ----- Origial Message -----
> From: "Michael Lincoln" <mlincoln1@gmail.com>
> To: <gmclist@temp.gmcnet.org>
> Sent: Wednesday, February 17, 2010 8:31 PM
> Subject: Re: [GMCnet] Injection versus Carbs
>
>
>> Has anyone tried a carb (a fixed carb, not an
>> altitude-adjusting one) that has been specifically leaned for
>> altitude? Does it detonate (too lean) at sea level? I'm
>> thinking that one of the experienced tinkerers might know.
>>
>> In airplane flying in the Rockies one leans to peak rpm (fixed
>> pitch prop), then richens to make the exhaust gas temp 50-100
>> degrees cooler for takeoff. There's a big difference in power:
>> running full rich (firewalled mixture control) compared to
>> optimally leaned makes a huge difference in a high
>> density-altitude situation. In the Utah mountains I once
>> foolishly filled up a Cessna 152 (a little underpowered
>> straight-tailed 152 from the 1950's) with avgas the night
>> before, and then took off the next day. My friend and I flew
>> the plane in ground effect for three miles to the edge of Bryce
>> Canyon (airport was 9000 MSL), in order to throw ourselves off
>> the edge and get some altitude beneath us. If I hadn't leaned
>> for altitude I'm sure we would never have even gotten into
>> ground effect. (By the time we got to the Grand Canyon 45 min
>> later, I had thermaled to 14,500 feet, and LA Center didn't
>> believe our type aircraft--an 89 hp 152--given our
>> altitude-encoding transponder rea
>> ding, but that's what rising air will do for you).
>>
>> Therefore I suspect an optimal air *mass* to fuel mixture might
>> make a significant difference in the GMC too. But, without the
>> manual mixture control, it may be that the altered air/fuel
>> volumetric mixture of the "mountain carb", when running at low
>> altitude with the air mass much greater, would result in a too
>> lean situation, with unacceptable detonation or at least higher
>> cylinder head/EGT and wear in the valve train.
>>
>> Has anyone tried it?
>>
>> Mike
>>
>>
>> On Feb 17, 2010, at 6:57 PM, Ken Henderson wrote:
>>
>>> Mike,
>>>
>>> Larry W. must be off line while travelling or he'd have chimed
>>> in: He got
>>> all excited about an altitude compensated Quadrajet he came
>>> across. He
>>> spent a lot of time and his expertise on getting it working --
>>> for a while.
>>> From what I recall of what he told me, it worked great as long
>>> as he kept
>>> working on it. As if the QJ's not complicated enough, imagine
>>> what those
>>> extra bellows, jets, needles, etc., would add. I don't
>>> remember whether
>>> he's running it right now -- I don't think so -- but I do know
>>> he's planning
>>> on port injecting his Cad 500 ASAP.
>>>
>>> Ken H.
>>> Americus, GA
>>> '76 X-Birchaven
>>> www.gmcwipersetc.com
>>>
>>>
>>> On Wed, Feb 17, 2010 at 6:34 PM, Matt Colie
>>> <mcolie@chartermi.net> wrote:
>>>
>>>>
>>>>
>>>> mlincoln wrote on Mon, 15 February 2010 16:31
>>>>> Does anyone have actual experience with "splitting the
>>>>> difference" in the
>>>> Quadrajet enrichment to suit a MSL of 4500 to 5000 feet? I
>>>> was once told
>>>> that some old Detroit iron came with a "high altitude option"
>>>> (possibly a
>>>> re-metered carb?). A shop in ...
>>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> List Information and Subscription Options:
>>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
>> GMCnet mailing list
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>
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| Re: [GMCnet] Injection versus Carbs [message #74243 is a reply to message #74232] |
Thu, 18 February 2010 11:17 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
|
Senior Member |
|
|
That info can be important. INformation with no use is "data". I want to track mileage less to know how light my wallet is but mileage drop off can be a first indication of problems in the motor. There are many issues with a motor that will start out reducung performance which will increase fuel use. You can also track your success at modifying, tuning and adjusting the motor. You can see how well or how bad things you do effect performance.
If you could use this info like this I think keeping such records is more than an exercise in math.
Jim Bounds
-------------------------
----- Original Message ----
From: Larry <slawrence111@yahoo.com>
To: gmclist@temp.gmcnet.org
Sent: Thu, February 18, 2010 10:06:19 AM
Subject: Re: [GMCnet] Injection versus Carbs
I was just reading your comments about how you have never tracked your mileage on the GMC, I must say I have let they go by as well it has been such a hassle.
I had a friend travel with me last time and he tried to track it. If his math was correct I may have an idea but who knows.
I have created a spread sheet for tracking mileage on an excel program.
I am pretty good with the formulas in excel so I tend to add more as I think of it.
All you would add is the date, present mileage and cost.
If you add just the present mileage, such as on the road in travel mode, it estimates mileage driven and mileage left.
The program will tell you your MPG, estimated miles per tank, how many miles you drove and how many miles are left, estimate of fuel left in the tank. It also gives an average of your MPG, Cost per fill and average cost. Yeah, sometimes I think I have too much time, HA!! Like that can happen...
It has a provision to account for the reserve gallons or just leave it out.
Truely an experiment in playing with numbers and if you are good with the formulas, you can tweek it as well.
If anyone would be interested in this program I could email it to you and you could play with it.
It is not much less clumbsy than writing the info on paper, but it is more fun and does all the computing.
If this can be helpful to you, let me know. I still update things and if you have any ideas to add, we could try that too.
Just a thought
LarC ( Always interested in numbers and would like to see the GMC numbers much higher - HAH! )
--
Gatsbys' CRUISER :d
74 GLACIER X, 260
455/APC/4 bagg'r(ver3)
Remflex Manifold gaskets
_______________________________________________
Purchased 08-18-04
_
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GMCnet mailing list
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| Re: [GMCnet] Injection versus Carbs [message #74246 is a reply to message #74243] |
Thu, 18 February 2010 11:33 |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
|
Senior Member |
|
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Hi,
At this point with our coach, not only do I not collect gas receipts I
rarely look at the number of gallons, just the sound as the tank fills. If I
looked the cost of gas per mile I might buy a sidecar for one of my dual
sport bikes and stay in motels. It's just about a tradeoff.
Second thing, when I look at the cost of a good towd, maintenance on it,
insurance and the extra gas to pull it. I'm thinking that on any future long
desination trips 1000 miles+ I'm going to rent from Enterprise. They are
everywhere and pretty darn good prices. I'll throw my Yamaha TW200 on the
rack for emergencies.
Or maybe one of Jim B's sidehacks on a small trailer. Jim, are you still in
the bike business!!!!
I still have a Howell FI system from the last group buy sitting right here
in my office. The cat sleeps on top of the box.
Thanks
Gary and Joanne Worobec
1973 GMC Glacier
Anza, CA
----- Original Message -----
From: "Jim Bounds" <gmccoop@yahoo.com>
To: <gmclist@temp.gmcnet.org>
Sent: Thursday, February 18, 2010 9:17 AM
Subject: Re: [GMCnet] Injection versus Carbs
That info can be important. INformation with no use is "data". I want to
track mileage less to know how light my wallet is but mileage drop off can
be a first indication of problems in the motor. There are many issues with a
motor that will start out reducung performance which will increase fuel use.
You can also track your success at modifying, tuning and adjusting the
motor. You can see how well or how bad things you do effect performance.
If you could use this info like this I think keeping such records is more
than an exercise in math.
Jim Bounds
-------------------------
----- Original Message ----
From: Larry <slawrence111@yahoo.com>
To: gmclist@temp.gmcnet.org
Sent: Thu, February 18, 2010 10:06:19 AM
Subject: Re: [GMCnet] Injection versus Carbs
I was just reading your comments about how you have never tracked your
mileage on the GMC, I must say I have let they go by as well it has been
such a hassle.
I had a friend travel with me last time and he tried to track it. If his
math was correct I may have an idea but who knows.
I have created a spread sheet for tracking mileage on an excel program.
I am pretty good with the formulas in excel so I tend to add more as I think
of it.
All you would add is the date, present mileage and cost.
If you add just the present mileage, such as on the road in travel mode, it
estimates mileage driven and mileage left.
The program will tell you your MPG, estimated miles per tank, how many miles
you drove and how many miles are left, estimate of fuel left in the tank. It
also gives an average of your MPG, Cost per fill and average cost. Yeah,
sometimes I think I have too much time, HA!! Like that can happen...
It has a provision to account for the reserve gallons or just leave it out.
Truely an experiment in playing with numbers and if you are good with the
formulas, you can tweek it as well.
If anyone would be interested in this program I could email it to you and
you could play with it.
It is not much less clumbsy than writing the info on paper, but it is more
fun and does all the computing.
If this can be helpful to you, let me know. I still update things and if you
have any ideas to add, we could try that too.
Just a thought
LarC ( Always interested in numbers and would like to see the GMC numbers
much higher - HAH! )
--
Gatsbys' CRUISER :d
74 GLACIER X, 260
455/APC/4 bagg'r(ver3)
Remflex Manifold gaskets
_______________________________________________
Purchased 08-18-04
_
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| Re: [GMCnet] Injection versus Carbs [message #74247 is a reply to message #73254] |
Thu, 18 February 2010 11:45 |
rallymaster
Messages: 662
Registered: February 2004
Location: North Plains, ORYGUN
Karma: -4
|
Senior Member |
|
|
It also gives warning of other things, like front wheel alignment and
forgetting to monitor tire pressure.
Over the years in many vehicles (before vehicle computers), I've noticed
an alignment made more difference in mileage than a tuneup.
ron c
On Thu, 18 Feb 2010 09:17:10 -0800 (PST) Jim Bounds <gmccoop@yahoo.com>
writes:
> That info can be important. INformation with no use is "data". I
> want to track mileage less to know how light my wallet is but
> mileage drop off can be a first indication of problems in the
> motor. There are many issues with a motor that will start out
> reducung performance which will increase fuel use. You can also
> track your success at modifying, tuning and adjusting the motor.
> You can see how well or how bad things you do effect performance.
>
> If you could use this info like this I think keeping such records is
> more than an exercise in math.
>
> Jim Bounds
> -------------------------
>
>
>
> ----- Original Message ----
> From: Larry <slawrence111@yahoo.com>
> To: gmclist@temp.gmcnet.org
> Sent: Thu, February 18, 2010 10:06:19 AM
> Subject: Re: [GMCnet] Injection versus Carbs
>
>
>
> I was just reading your comments about how you have never tracked
> your mileage on the GMC, I must say I have let they go by as well it
> has been such a hassle.
>
> I had a friend travel with me last time and he tried to track it.
> If his math was correct I may have an idea but who knows.
>
> I have created a spread sheet for tracking mileage on an excel
> program.
>
> I am pretty good with the formulas in excel so I tend to add more as
> I think of it.
>
> All you would add is the date, present mileage and cost.
>
> If you add just the present mileage, such as on the road in travel
> mode, it estimates mileage driven and mileage left.
>
> The program will tell you your MPG, estimated miles per tank, how
> many miles you drove and how many miles are left, estimate of fuel
> left in the tank. It also gives an average of your MPG, Cost per
> fill and average cost. Yeah, sometimes I think I have too much
> time, HA!! Like that can happen...
>
> It has a provision to account for the reserve gallons or just leave
> it out.
>
> Truely an experiment in playing with numbers and if you are good with
> the formulas, you can tweek it as well.
>
> If anyone would be interested in this program I could email it to
> you and you could play with it.
>
> It is not much less clumbsy than writing the info on paper, but it
> is more fun and does all the computing.
>
> If this can be helpful to you, let me know. I still update things
> and if you have any ideas to add, we could try that too.
>
> Just a thought
>
> LarC ( Always interested in numbers and would like to see the GMC
> numbers much higher - HAH! )
>
>
>
> --
> Gatsbys' CRUISER :d
> 74 GLACIER X, 260
> 455/APC/4 bagg'r(ver3)
> Remflex Manifold gaskets
> _______________________________________________
> Purchased 08-18-04
>
> _
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
>
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
Ron & Linda Clark
1978 Eleganza II
North Plains, ORYGUN
_______________________________________________
GMCnet mailing list
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Ron & Linda Clark
North Plains, ORYGUN
78 Eleganza II
|
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| Re: [GMCnet] Injection versus Carbs [message #74253 is a reply to message #74227] |
Thu, 18 February 2010 08:38 |
mlincoln
Messages: 107
Registered: August 2006
Location: Salt Lake City
Karma: 0
|
Senior Member |
|
|
I understand and agree, Matt. First that auto carbs are certainly more complex. Second, that carburetors are volume pumps and not mass pumps. Regarding your second point, I earlier noted that very same problem: the volume pumping of air stays the about the same in the carburetor, even when the atmospheric pressure drops significantly. When this happens, usually with increasing altitude, the *mass* pumping of air decreases significantly while the volume pumping of fuel remains about the same. (Perhaps temperature and thermal expansion/contraction can affect fuel mass pumping by a few percent). In this case, the molar matching of fuel molecules to air molecules is significantly, and non-optimally, altered and affects the mixture to the detriment of performance. The mixture richens with increasing altitude, or if optimally leaned at altitude and subsequently not adjusted, becomes too lean as altitude decreases.
Naturally, any engine is less powerful when less oxygen can be burned, but the non-optimal matching of air to fuel further degrades performance and raises emissions as altitude increases. In airplanes, we correct the second factor with our bone-simple mixture controls. We just have to suffer with the first factor unless we are turbocharged, which probably decreases reliability and certainly increases aircraft power plant cost significantly. Of course, fuel injection with air mass meters (e.g., a hot wire in the airstream) can correct those deficiencies, but it sounds to me that the juice may not be worth the squeeze with our engines. Interestingly, many of the newest self-launching sailplanes (like this one: http://www.alisport.com/eu/eng/index.html ) now have EFI. My wife is in dental school now...just a few rich kids with bad teeth down the road a few years, and maybe I can afford one :-)
So, I agree with you entirely. But here's the core question: can the volume pumping characteristics of auto carburetors be predictably altered in a beneficial way in the GMC MH application, using either 1) different jets/metering rods (by someone who knows what they're doing, specifically not me), or 2) this adjustable part throttle screw that Kosier mentioned, in order to adjust the volumetric mixing properties of the carburetor so as to achieve a better mass air/fuel balance at high (or even intermediate, e.g., Appalachian) altitudes? Or is it like the aircraft turbocharger, expensive and perhaps too much bother--what do you think?
Specifically, I'm thinking of trying to acquire a second Quadrajet (actually, I have one) and have it rebuilt with slightly leaner mixture, perhaps optimized for 5000 feet MSL. Then I'd have two carbs and could change at will; it looks like a simple job for a tyro mechanic with little skill (which would describe me). In your opinion, is there anything to Kosier's adjusting screw in the latter model Quadrajets?
Mike
On Feb 18, 2010, at 8:49 AM, Matt Colie wrote:
>
>
> Mike and Ken (and other pilots onboard),
>
> There is a danger in relating aircraft carburetors to their distant automotive cousins.
>
> Aircraft carburetors are relatively simple when compared to the automotive version for similar rating.
>
> It you had all the courses in engineering school, you were taught that carburetors were mass-flow devices and as such should match a mass of air with a mass of fuel (thus says the mathematics).
>
> Unfortunately, this is not the case. There are profound volumetric effects. Matching fuel volume with air volume does not work well when the volume of air has less mass. This can cause some profound issues even east of the Mississippi. (Like when the portable equipment you counted on will not run at 4KMSL.)
>
> It matters more to automotive than aircraft because:
> Aircraft traditionally have pilot adjustable mixture and carburetor heat.
> Aircraft are a stable load situation so time to manually adjust the mixture is available.
> Automotive applications require that operation be predicable with operators regardless of experience and education.
> Automotive engine operational envelope is extremely large and way outside normal good practices turn-down limits.
>
> There are many reasons why the automotive industry has cheerfully abandon the artform of calibrating our old carburetors. Emissions was just a real good excuse to make the investment.
>
> Matt
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumiere (say show-me-air)
> SE Michigan
> _______________________________________________
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Mike
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| Re: [GMCnet] Injection versus Carbs [message #74255 is a reply to message #73254] |
Thu, 18 February 2010 14:11 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
|
Senior Member |
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|
I am not an expert on quadrajets. Have rebult a few. I have ruggles book and all would benifit reading it even if you never plan on turning a wrench on your carb. I've read it THREE times. Purchased Ruggles rebuild kit. Very expensive but worth it. The APT system,,,plunger,hangers,rods and spring are adjustable by the screw but it only adjusts how LOW the rods go when Vac. holds down the plunger. When vac. drops, up go the rods and you are richer. It does NOT adjust how high the rods go or when. When is adjustable by which spring. AFR is adjustable by which rods AND which jets the rods are in. You really need to read the book. Having a difftrent carb for altitude change is a novel idea BUT, it would need to be EXACTLY the same, lots of small passages in a quadrajet. What I mean by the same is to quantify changing to a diffrent carb with only diffrent rods or jets all the other passages are not the same, you cant tell if the jet change is what made the diffrence.
Paul(whos going to start a fourth time)Leavitt
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| Re: [GMCnet] Injection versus Carbs [message #74259 is a reply to message #73254] |
Thu, 18 February 2010 15:08 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
|
Senior Member |
|
|
The Altitude Compensating carbs work great...UNLESS...you have a Wide band O2 and a FA meter. Now that sounds strange, but the FA tells you what the carb is *really* doing in terms of FA at all speeds,throttle positions and loads. If yo hav ethe O2 meter, I can guarentee, you'r gonna want to change something. In the Q-jet, each curcuit (idle, part throttle, primary circuit, power inrichment, WOT primary, part throttle secondary, all in between throttle positions in the secondary, and WOT secondary) all have an effect on the others. Change the idle screws by opening them up a bit for a richer mixture at idle and it richens up all of the other throttle positions...though to a more minor degree, the wider open the throttle gets. A change in jets or rods directly effects not only the primary, but the secondary circuit. Change the power piston spring, it changes the entire primary circuit enrichment cycle relative to throttle position. In the secondary, while the jet is fixed, there is a nearly infinate (exaggerating)number of secondary rods...each of which has it's own enrichment curve depending on vacuum, and throttle position.
So, now with the Altitude Compensating carb, add in one more power valve with yet another rod to the primary circuit, and an aneroid that is hooked to a rod and is adjustable like the APT, and suddenly you have more variables than you can imagine. After playing with it for several months, I finally gave up trying to tune it for the FA's that I wanted at the different throttle positions and loads, and got a Q-jet with a Adjustable Part Throttle (APT) off of a, IIRC...81'chevy 454 PU. I'm finally getting close to what I want and i'm changing to a MPI. Why???...because it's there....and I can make changes with a laptop instead of having to take the Carb apart.
IMO, unless you know what you are doing and have a FA meter to compliment your tuning procedure, you have no business changing rods, jets, or making ATP, or any other adjustments to a q-jet. To lean, and you could burn up a motor...to rich and you contaminate the oil with washed down fuel doing over the long term, damage to your motor. If you are not sure of what you are doing, get a Patterson Carb, and be happy with it. JMHO
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Injection versus Carbs [message #74359 is a reply to message #74261] |
Fri, 19 February 2010 13:44 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
|
Senior Member |
|
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| wally wrote on Thu, 18 February 2010 15:33 |
| Larry wrote on Thu, 18 February 2010 15:08 |
The Altitude Compensating carbs work great...UNLESS...you have a Wide band O2 and a FA meter. Now that sounds strange, but the FA tells you what the carb is *really* doing in terms of FA at all speeds,throttle positions and loads. If yo hav ethe O2 meter, I can guarentee, you'r gonna want to change something.
|
Like Larry I had the wide band installed with the stock Qjet for a year. AFR goes all over the place.
|
Wally,
Yup, sure does. Took a while for my pea brain to adjust to the variety of FA mixtures I was getting and get my brain to make some kind of average of what I was seeing. It was almost as if it was reading each and every exhaust pulse that was coming through. I even called the company tech support to ask if they had some kind of box that I could attach to it that would average the pulses over a 1/2 or 1 second period of time. Techy thought that was pretty funny.
So...how goes the mega-squirt experiment?
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Injection versus Carbs [message #74366 is a reply to message #74359] |
Fri, 19 February 2010 14:44 |
 |
wally
Messages: 643
Registered: August 2004
Location: Omaha Nebraska
Karma: 5
|
Senior Member |
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| Larry wrote on Fri, 19 February 2010 13:44 |
| wally wrote on Thu, 18 February 2010 15:33 |
| Larry wrote on Thu, 18 February 2010 15:08 |
The Altitude Compensating carbs work great...UNLESS...you have a Wide band O2 and a FA meter. Now that sounds strange, but the FA tells you what the carb is *really* doing in terms of FA at all speeds,throttle positions and loads. If yo hav ethe O2 meter, I can guarentee, you'r gonna want to change something.
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Like Larry I had the wide band installed with the stock Qjet for a year. AFR goes all over the place.
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Wally,
Yup, sure does. Took a while for my pea brain to adjust to the variety of FA mixtures I was getting and get my brain to make some kind of average of what I was seeing. It was almost as if it was reading each and every exhaust pulse that was coming through. I even called the company tech support to ask if they had some kind of box that I could attach to it that would average the pulses over a 1/2 or 1 second period of time. Techy thought that was pretty funny.
So...how goes the mega-squirt experiment?
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Well it was running when I parked it but we have been snowed under for months. lets take this off net to forum PM so we don't bother everyone...
Wally Anderson
Omaha NE
75 Glenbrook
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