Jim Bounds interesting recent posts

[jerry work]

I have followed with interest his comments about why carbs no longer work (=
todays gas won=E2=80=99t vaporize correctly for use in a carb) and now why =
our engines are blowing up mote frequently (they run too hot under some con=
dition). Take a look at the presentation I did on Fitech (http://www=
.bdub.net/FiTech_is_the_Real_Deal.pdf). Near the end are two important sli=
des that I think help explain what he is saying. The slide with the two ch=
arts is very telling. Those charts are based on an engine running pure gas=
oline with a stoichiometric air/fuel ratio of 14.7:1. One chart shows peak=
power at an air fuel ratio of around 12.5:1 (quite rich) while peak econom=
y is around 16:1 (way too lean for our engines to survive for very long). =
Those charts are based on UNADULTERATED gasoline. The curves for gasoline =
laced with alcohol would look much differently. The slide on the nex=
t page shows stoichiometric A/F ratios for various chemical compounds. For=
octane it is 15:1, for ethanol it is 9:1. We not only have been adding et=
hanol, we have also added a number of other distillates and removed others.=
So, just as he has been saying, everything we learned about engines when =
we were all much younger is out the window given whatever it is we now pump=
into our fuel tanks. Just for giggles, see what happens to those curves i=
f the only change was adding 10% alcohol. The stoichiometric would shift f=
rom 14.7 to 14.1. Now guess what happens if you go to lean, either because=
you reprogram your fuel injection to do that, or because your carb gets di=
rty inside and does it on its own without you even knowing it, or because y=
ou monkey around with the jets, air correctors, power valve springs, etc. i=
n the hope of better mileage. On flat land you might get away with that if=
you drive at 50 to 60 mph where the air drag is low, but climb any kind of=
hill or load the engine up with head wind or by speeding up and you will q=
uickly be running way too lean for the conditions and way to hot for any ki=
nd of engine longevity. Just what he has been saying. I am not a petr=
oleum engineer so don=E2=80=99t know for sure how those curves change shape=
for whatever is in our fuel today, but my guess is however those curves ch=
ange the result is we should now be striving to burn MORE FUEL day in and d=
ay out if we want to keep these old engines healthy. I=E2=80=99m going to =
guess there is a direct correlation between fuel consumption and engine lif=
e. Likely 8mpg is around the BEST one should shoot for these days. =
How many times have we heard people say that their coaches ran much better =
and got much better fuel economy driving in Canada on premium fuel with no =
alcohol. The only way that could happen is if that coach was set up way to=
o lean for driving on gasoline laced with alcohol. My thoughts anyway. =
Jerry Jerry Work The Dovetail Joint Fine furniture designed and=
hand crafted in the 1907 former Masonic Temple building in historic Kerby,=
OR glwork http://jerrywork.com =

 

[Keith V]

I'm still trying to figure out exactly what E10 looks like on a O2 Sensor, =
I have a wide band sensor I use with my carb. >From what I understand,=
an O2 sensor doesn't actually measure air fuel ratio directly but computes=
it from oxygen in the exhaust. This measurement is called Lamda. A La=
mbda of 1 gives you a stoichiometric AFR no matter what the fuel mix S=
o if you add ethanol the indicated AFR is incorrect, but an AFR of 14.7 ( a=
Lambda of 1 ) is still stoichiometric. I think that anyone tuning =
anything these days has no excuse to not be running a WB O2, theyre cheap a=
nd accurate. The other question is where on the AFR curve should we=
be running. I'm betting about stoichiometric or slightly richer. But =
no one seems to be publishing that info ________________________=
________ From: Gmclist on behalf of Ger=
ald Work Sent: Friday, November 10, 2017 9:58:58 AM To=
: GMC Motor Home Post Subject: [GMCnet] Jim Bounds interesting recent pos=
ts I have followed with interest his comments about why carbs no longe=
r work (todays gas won=E2=80=99t vaporize correctly for use in a carb) and =
now why our engines are blowing up mote frequently (they run too hot under =
some condition). Take a look at the presentation I did on Fitech (http=
://www.bdub.net/FiTech_is_the_Real_Deal.pdf). Near the end are two importa=
nt slides that I think help explain what he is saying. The slide with the =
two charts is very telling. Those charts are based on an engine running pu=
re gasoline with a stoichiometric air/fuel ratio of 14.7:1. One chart show=
s peak power at an air fuel ratio of around 12.5:1 (quite rich) while peak =
economy is around 16:1 (way too lean for our engines to survive for very lo=
ng). Those charts are based on UNADULTERATED gasoline. The curves for gas=
oline laced with alcohol would look much differently. The slide on the=
next page shows stoichiometric A/F ratios for various chemical compounds. =
For octane it is 15:1, for ethanol it is 9:1. We not only have been addin=
g ethanol, we have also added a number of other distillates and removed oth=
ers. So, just as he has been saying, everything we learned about engines w=
hen we were all much younger is out the window given whatever it is we now =
pump into our fuel tanks. Just for giggles, see what happens to those curv=
es if the only change was adding 10% alcohol. The stoichiometric would shi=
ft from 14.7 to 14.1. Now guess what happens if you go to lean, either bec=
ause you reprogram your fuel injection to do that, or because your carb get=
s dirty inside and does it on its own without you even knowing it, or becau=
se you monkey around with the jets, air correctors, power valve springs, et=
c. in the hope of better mileage. On flat land you might get away with tha=
t if you drive at 50 to 60 mph where the air drag is low, but climb any kin=
d of hill or load the engine up with head wind or by speeding up and you wi=
ll quickly be running way too lean for the conditions and way to hot for an=
y kind of engine longevity. Just what he has been saying. I am not a =
petroleum engineer so don=E2=80=99t know for sure how those curves change s=
hape for whatever is in our fuel today, but my guess is however those curve=
s change the result is we should now be striving to burn MORE FUEL day in a=
nd day out if we want to keep these old engines healthy. I=E2=80=99m going=
to guess there is a direct correlation between fuel consumption and engine=
life. Likely 8mpg is around the BEST one should shoot for these days. =
How many times have we heard people say that their coaches ran much bett=
er and got much better fuel economy driving in Canada on premium fuel with =
no alcohol. The only way that could happen is if that coach was set up way=
too lean for driving on gasoline laced with alcohol. My thoughts anyway.=
Jerry Jerry Work The Dovetail Joint Fine furniture designed =
and hand crafted in the 1907 former Masonic Temple building in historic Ker=
by, OR glwork http://jerrywork.com =
_______________________________________________ GMCnet mailing list=
Unsubscribe or Change List Options: http://list.gmcnet.org/mailman/lis=
tinfo/gmclist_list.gmcnet.org

 

[jim kanomata1]

Keith,
We acquired a Lambda meter back in 1994 to help program the Hal Tech ECM
that I was running. Back then it was a $ 2,200 instrument.
We used that to help us with EFI as well as carb units.
Until then, I had no idea of how the ratio was based.
Since graduation from engineering, I just don't have the mind to get into
details like I should.
Glad to see that you understand. Thanks.

> I'm still trying to figure out exactly what E10 looks like on a O2 Sensor,
> I have a wide band sensor I use with my carb.
>
> From what I understand, an O2 sensor doesn't actually measure air fuel
> ratio directly but computes it from oxygen in the exhaust.
>
> This measurement is called Lamda. A Lambda of 1 gives you a stoichiometric
> AFR no matter what the fuel mix
>
> So if you add ethanol the indicated AFR is incorrect, but an AFR of 14.7 (
> a Lambda of 1 ) is still stoichiometric.
>
>
> I think that anyone tuning anything these days has no excuse to not be
> running a WB O2, theyre cheap and accurate.
>
>
> The other question is where on the AFR curve should we be running.
>
> I'm betting about stoichiometric or slightly richer. But no one seems to
> be publishing that info
>
>
>
> ________________________________
> From: Gmclist on behalf of Gerald Work <
> glwork>
> Sent: Friday, November 10, 2017 9:58:58 AM
> To: GMC Motor Home Post
> Subject: [GMCnet] Jim Bounds interesting recent posts
>
> I have followed with interest his comments about why carbs no longer work
> (todays gas won’t vaporize correctly for use in a carb) and now why our
> engines are blowing up mote frequently (they run too hot under some
> condition).
>
> Take a look at the presentation I did on Fitech (
> http://www.bdub.net/FiTech_is_the_Real_Deal.pdf). Near the end are two
> important slides that I think help explain what he is saying. The slide
> with the two charts is very telling. Those charts are based on an engine
> running pure gasoline with a stoichiometric air/fuel ratio of 14.7:1. One
> chart shows peak power at an air fuel ratio of around 12.5:1 (quite rich)
> while peak economy is around 16:1 (way too lean for our engines to survive
> for very long). Those charts are based on UNADULTERATED gasoline. The
> curves for gasoline laced with alcohol would look much differently.
>
> The slide on the next page shows stoichiometric A/F ratios for various
> chemical compounds. For octane it is 15:1, for ethanol it is 9:1. We not
> only have been adding ethanol, we have also added a number of other
> distillates and removed others. So, just as he has been saying, everything
> we learned about engines when we were all much younger is out the window
> given whatever it is we now pump into our fuel tanks. Just for giggles,
> see what happens to those curves if the only change was adding 10%
> alcohol. The stoichiometric would shift from 14.7 to 14.1. Now guess what
> happens if you go to lean, either because you reprogram your fuel injection
> to do that, or because your carb gets dirty inside and does it on its own
> without you even knowing it, or because you monkey around with the jets,
> air correctors, power valve springs, etc. in the hope of better mileage.
> On flat land you might get away with that if you drive at 50 to 60 mph
> where the air drag is low, but climb any kind of hill or load the engine up
> with head wind or by speeding up and you will quickly be running way too
> lean for the conditions and way to hot for any kind of engine longevity.
> Just what he has been saying.
>
> I am not a petroleum engineer so don’t know for sure how those curves
> change shape for whatever is in our fuel today, but my guess is however
> those curves change the result is we should now be striving to burn MORE
> FUEL day in and day out if we want to keep these old engines healthy. I’m
> going to guess there is a direct correlation between fuel consumption and
> engine life. Likely 8mpg is around the BEST one should shoot for these
> days.
>
> How many times have we heard people say that their coaches ran much better
> and got much better fuel economy driving in Canada on premium fuel with no
> alcohol. The only way that could happen is if that coach was set up way
> too lean for driving on gasoline laced with alcohol. My thoughts anyway.
>
> Jerry
>
> Jerry Work
> The Dovetail Joint
> Fine furniture designed and hand crafted in the 1907 former Masonic Temple
> building in historic Kerby, OR
>
> glwork
> http://jerrywork.com
>
>
>
>
>
>
>
>
>
> _______________________________________________
> 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
http://www.appliedgmc.com
1-800-752-7502

 

[Jim Hupy]

When burning long chain hydrocarbons, so many by products are created that
it is hard to sort it all out. Today's motor fuels "ain't your fathers
motor fuels". Using a voltage of less than 2 volts to tell you what your
air fuel ratio is, is an exercise in futility, in my opinion. Lamda is only
the tip of the iceberg. Lean means one thing with leaded fuels, something
else entirely with alcohol blended fuels. The refrigeration effect of
various fuels is all over the map as well. It is not likely to improve any
time soon.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Keith,
> We acquired a Lambda meter back in 1994 to help program the Hal Tech ECM
> that I was running. Back then it was a $ 2,200 instrument.
> We used that to help us with EFI as well as carb units.
> Until then, I had no idea of how the ratio was based.
> Since graduation from engineering, I just don't have the mind to get into
> details like I should.
> Glad to see that you understand. Thanks.
>

>
> > I'm still trying to figure out exactly what E10 looks like on a O2
> Sensor,
> > I have a wide band sensor I use with my carb.
> >
> > From what I understand, an O2 sensor doesn't actually measure air fuel
> > ratio directly but computes it from oxygen in the exhaust.
> >
> > This measurement is called Lamda. A Lambda of 1 gives you a
> stoichiometric
> > AFR no matter what the fuel mix
> >
> > So if you add ethanol the indicated AFR is incorrect, but an AFR of 14.7
> (
> > a Lambda of 1 ) is still stoichiometric.
> >
> >
> > I think that anyone tuning anything these days has no excuse to not be
> > running a WB O2, theyre cheap and accurate.
> >
> >
> > The other question is where on the AFR curve should we be running.
> >
> > I'm betting about stoichiometric or slightly richer. But no one seems to
> > be publishing that info
> >
> >
> >
> > ________________________________
> > From: Gmclist on behalf of Gerald
> Work <
> > glwork>
> > Sent: Friday, November 10, 2017 9:58:58 AM
> > To: GMC Motor Home Post
> > Subject: [GMCnet] Jim Bounds interesting recent posts
> >
> > I have followed with interest his comments about why carbs no longer work
> > (todays gas won’t vaporize correctly for use in a carb) and now why our
> > engines are blowing up mote frequently (they run too hot under some
> > condition).
> >
> > Take a look at the presentation I did on Fitech (
> > http://www.bdub.net/FiTech_is_the_Real_Deal.pdf). Near the end are two
> > important slides that I think help explain what he is saying. The slide
> > with the two charts is very telling. Those charts are based on an engine
> > running pure gasoline with a stoichiometric air/fuel ratio of 14.7:1.
> One
> > chart shows peak power at an air fuel ratio of around 12.5:1 (quite rich)
> > while peak economy is around 16:1 (way too lean for our engines to
> survive
> > for very long). Those charts are based on UNADULTERATED gasoline. The
> > curves for gasoline laced with alcohol would look much differently.
> >
> > The slide on the next page shows stoichiometric A/F ratios for various
> > chemical compounds. For octane it is 15:1, for ethanol it is 9:1. We
> not
> > only have been adding ethanol, we have also added a number of other
> > distillates and removed others. So, just as he has been saying,
> everything
> > we learned about engines when we were all much younger is out the window
> > given whatever it is we now pump into our fuel tanks. Just for giggles,
> > see what happens to those curves if the only change was adding 10%
> > alcohol. The stoichiometric would shift from 14.7 to 14.1. Now guess
> what
> > happens if you go to lean, either because you reprogram your fuel
> injection
> > to do that, or because your carb gets dirty inside and does it on its own
> > without you even knowing it, or because you monkey around with the jets,
> > air correctors, power valve springs, etc. in the hope of better mileage.
> > On flat land you might get away with that if you drive at 50 to 60 mph
> > where the air drag is low, but climb any kind of hill or load the engine
> up
> > with head wind or by speeding up and you will quickly be running way too
> > lean for the conditions and way to hot for any kind of engine longevity.
> > Just what he has been saying.
> >
> > I am not a petroleum engineer so don’t know for sure how those curves
> > change shape for whatever is in our fuel today, but my guess is however
> > those curves change the result is we should now be striving to burn MORE
> > FUEL day in and day out if we want to keep these old engines healthy.
> I’m
> > going to guess there is a direct correlation between fuel consumption and
> > engine life. Likely 8mpg is around the BEST one should shoot for these
> > days.
> >
> > How many times have we heard people say that their coaches ran much
> better
> > and got much better fuel economy driving in Canada on premium fuel with
> no
> > alcohol. The only way that could happen is if that coach was set up way
> > too lean for driving on gasoline laced with alcohol. My thoughts anyway.
> >
> > Jerry
> >
> > Jerry Work
> > The Dovetail Joint
> > Fine furniture designed and hand crafted in the 1907 former Masonic
> Temple
> > building in historic Kerby, OR
> >
> > glwork
> > http://jerrywork.com
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> > 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
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[wally anderson]

> I'm still trying to figure out exactly what E10 looks like on a O2 Sensor, I have a wide band sensor I use with my carb.
>
> From what I understand, an O2 sensor doesn't actually measure air fuel ratio directly but computes it from oxygen in the exhaust.
>
> This measurement is called Lamda. A Lambda of 1 gives you a stoichiometric AFR no matter what the fuel mix
>
> So if you add ethanol the indicated AFR is incorrect, but an AFR of 14.7 ( a Lambda of 1 ) is still stoichiometric.
>
>
> I think that anyone tuning anything these days has no excuse to not be running a WB O2, theyre cheap and accurate.
>
>
> The other question is where on the AFR curve should we be running.
>
> I'm betting about stoichiometric or slightly richer. But no one seems to be publishing that info

Here is the commanded afr table we've been using for that last few years. I had a wideband with the carb initially and was surprised how wide the
range was. We don't need to run 14.7 to keep a catalytic converter lit and can tune for effect.
http://www.gmcmhphotos.com/photos/power-level-valve-fitting/p63934-commanded-afr-table-2013.html
http://www.gmcmhphotos.com/photos/power-level-valve-fitting/p63934-commanded-afr-table-2013.html
--
Wally Anderson
Omaha NE
75 Glenbrook
Megasquirt III injection
Bob Stone hydroBOOOOST
Manny reaction arm system
Branscombe Kelsey Hayes park brake
http://wallyandsue.blogspot.com/

 

[Matt Colie]

I did read JimB's blog, and there is a little I disagree with but there is also very little hard information there.

As an auto-lab rat from the early 70's (on and off), I can tell you for a fact that at lot of both Jim's and your premise is correct, but some is not.


Since the early 70's (at Chrysler Proving Grounds) is has been a stated fact that the carburetors we all know are not a vaporizing or gasifying
device. In actual fact, the industry has referred to them as "solid fuel" carburetors for years. While the droplet size does matter for emissions
(back when a carburetor could even meet those standards), there was a running game (with a large number of really strange plays) between large and
small. Small droplets cold burn faster and the larger more slowly. Not too different than gun powder grain size. Which you wanted depended on just
what you were trying to accomplish at that moment. The capability to maintain a stoichiometric over a wide band did not arrive until the EGO sensors
got reliable. Even then, the "closed loop" carburetors were not that good at much of anything.

Other running issue is: What is gasoline?
Even before "reformulating" this was an open question. When we were getting non-indolene test fuels, we always got a report with the carbon/hydrogen
ratio. even if this number was in target, we still could only use indolene (a specific chemical hydrocarbon that can be used as motor fuel) because
it was the only thing stable enough to give stable emissions values.

So, the fact that reformulated motorfuel may have a stoich number that is other than 14.68 is just not an issue. From an SI engine's point of view,
there is little change over a significantly wide range. Again, this is just one of the problems that new engine controls manage. Just about all of
the engines that have a EGO per bank and a modern ECU, are actually doing a cylinder by cylinder mixture control. This has to happen for current
standards. It was not desired in the mid-70s cat cars, because they counted on the rich/lean pulses to keep the cat lit and still provide enough O2
for the desired reactions to complete.

Then there is the issue that not all the cylinders see the same mixture (the end cylinders often get lean) with any central fuel feed system. The
initial charge pressure (present in the cylinder when the intake valve closes) has a lot to do with what is going to happen when the fire gets
started. No, all the cylinders of an engine are never the same and less than a wide open manifold only exacerbates that issue by steering the charge
mixture in different directions.

We live east of the Mississippi and rarely encounter altitudes above 6KMSL, but the coach rolled over the Big Horn on the way to Yellowstone and the
coach did not complain. We even had to go around a couple of little four-wheels that could not keep speed up at 9200MSL (according to my GPS). They
were all too new to be open loop. And, we still did our regular 9.2 for that journey.

So, before you get all fired up to change to a tack-on "fuel injection", decide if it is something you really want to do.

As Dick Paterson has been known to say, most carburetor problems start with the ignition. I am not fond of HEI, but it can be serviceable, you just
have to be sure you have the spares along. But, you should carry ignition spares in any case.

Matt - I'll get down off the milk crate now, I have some passcar work to do today still.


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

 

[Rdenney]

Jerry, I don't want to open a can of worms, but the longevity of the FITech
unit, with its electronics in a sometimes very hot throttle body, has been
questioned. One of the coaches you sold had a FITech system and suffered a
sudden fuel delivery failure for the new owners on their trip home. What
was the final diagnosis of that failure? There was speculation at the time
about effect of heat on the electronics.

I'm attracted to the FITech for that inevitable time when I lose faith in
my carb and have to send it off for rebuilding. I like the relatively
simple installation, which fits with my sharp limitations on tinkering
time. Until then, I have a good mechanical temperature gauge and if my
engine ever runs hot, it's keeping that fact a tight secret. I did not see
any evidence of overly lean running when I pulled the plugs during my
recent (preventative maintenance) engine replacement.

I recall (probably inaccurately) comments from Dick Balsley from years ago
that lean running and even detonation are not problems at part throttle.
The question is how much we are opening the throttle for given conditions,
and is the power enrichment feature kicking in early enough? That led to a
discussion of power valve springs at the time. He said Rochester designed
for richness to overcome the manufacturing tolerance in the carbs and to
overcome the variation in mixture caused by intake manifold passages. The
number 15% comes to my mind as being the target (6% for the carb itself),
which means a design AFR of no more than 12.7 during power enrichment (when
it is critical), to ensure that all air has fuel to burn instead of metal,
even with pure gasoline.

Does an O2 sensor average the reading across all cylinders? (And it only
reads one bank.) If so, I would want it 10% rich just to keep one cylinder
from leaning out at WOT as a result of intake mixture variability.

Rick "may be remembering this wrong" Denney

> I have followed with interest his comments about why carbs no longer work
> (todays gas won’t vaporize correctly for use in a carb) and now why our
> engines are blowing up mote frequently (they run too hot under some
> condition).
>
> Take a look at the presentation I did on Fitech (
> http://www.bdub.net/FiTech_is_the_Real_Deal.pdf). Near the end are two
> important slides that I think help explain what he is saying. The slide
> with the two charts is very telling. Those charts are based on an engine
> running pure gasoline with a stoichiometric air/fuel ratio of 14.7:1. One
> chart shows peak power at an air fuel ratio of around 12.5:1 (quite rich)
> while peak economy is around 16:1 (way too lean for our engines to survive
> for very long). Those charts are based on UNADULTERATED gasoline. The
> curves for gasoline laced with alcohol would look much differently.
>
> ...
>
> Jerry
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com

 

[bd5av8r]

I'd imagine both of the "Jims" have well engineered EFI systems that will
work for us in a GMC. (Yes I know I don't have one yet. Shhhh. lol)
Holley also has a bolt on EFI as does others. The OP makes a lot of sense.
Carburetors and today's "gas" are NOT meant for each other. Make sure your
engine
bay has a way to stay cool, make sure you have the proper thermostat in
your engine to help with cooling. Use a "water-wetter" it will help with
keeping the engine cooler.
A hot engine is never good. A proper EFI with todays fuel and a proper
operating cooling system will help engines to stay alive longer.

Sammy
GMCless (shhh! lol)

> I did read JimB's blog, and there is a little I disagree with but there is
> also very little hard information there.
>
> As an auto-lab rat from the early 70's (on and off), I can tell you for a
> fact that at lot of both Jim's and your premise is correct, but some is not.
>
>
> Since the early 70's (at Chrysler Proving Grounds) is has been a stated
> fact that the carburetors we all know are not a vaporizing or gasifying
> device. In actual fact, the industry has referred to them as "solid fuel"
> carburetors for years. While the droplet size does matter for emissions
> (back when a carburetor could even meet those standards), there was a
> running game (with a large number of really strange plays) between large and
> small. Small droplets cold burn faster and the larger more slowly. Not
> too different than gun powder grain size. Which you wanted depended on just
> what you were trying to accomplish at that moment. The capability to
> maintain a stoichiometric over a wide band did not arrive until the EGO
> sensors
> got reliable. Even then, the "closed loop" carburetors were not that good
> at much of anything.
>
> Other running issue is: What is gasoline?
> Even before "reformulating" this was an open question. When we were
> getting non-indolene test fuels, we always got a report with the
> carbon/hydrogen
> ratio. even if this number was in target, we still could only use
> indolene (a specific chemical hydrocarbon that can be used as motor fuel)
> because
> it was the only thing stable enough to give stable emissions values.
>
> So, the fact that reformulated motorfuel may have a stoich number that is
> other than 14.68 is just not an issue. From an SI engine's point of view,
> there is little change over a significantly wide range. Again, this is
> just one of the problems that new engine controls manage. Just about all of
> the engines that have a EGO per bank and a modern ECU, are actually doing
> a cylinder by cylinder mixture control. This has to happen for current
> standards. It was not desired in the mid-70s cat cars, because they
> counted on the rich/lean pulses to keep the cat lit and still provide
> enough O2
> for the desired reactions to complete.
>
> Then there is the issue that not all the cylinders see the same mixture
> (the end cylinders often get lean) with any central fuel feed system. The
> initial charge pressure (present in the cylinder when the intake valve
> closes) has a lot to do with what is going to happen when the fire gets
> started. No, all the cylinders of an engine are never the same and less
> than a wide open manifold only exacerbates that issue by steering the charge
> mixture in different directions.
>
> We live east of the Mississippi and rarely encounter altitudes above
> 6KMSL, but the coach rolled over the Big Horn on the way to Yellowstone and
> the
> coach did not complain. We even had to go around a couple of little
> four-wheels that could not keep speed up at 9200MSL (according to my GPS).
> They
> were all too new to be open loop. And, we still did our regular 9.2 for
> that journey.
>
> So, before you get all fired up to change to a tack-on "fuel injection",
> decide if it is something you really want to do.
>
> As Dick Paterson has been known to say, most carburetor problems start
> with the ignition. I am not fond of HEI, but it can be serviceable, you
> just
> have to be sure you have the spares along. But, you should carry ignition
> spares in any case.
>
> Matt - I'll get down off the milk crate now, I have some passcar work to
> do today still.
>
>
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[emerystora]

I chuckle when I hear about water wetters. Do you know what is in them or are you acting on blind faith on their advertising or on what you read on the label?

They contain glycols which should not do any harm to your engine but will do nothing good more than a well formulated antifreeze solution will.

Emery Stora
77 Kingsley
Frederick, CO

>
> I'd imagine both of the "Jims" have well engineered EFI systems that will
> work for us in a GMC. (Yes I know I don't have one yet. Shhhh. lol)
> Holley also has a bolt on EFI as does others. The OP makes a lot of sense.
> Carburetors and today's "gas" are NOT meant for each other. Make sure your
> engine
> bay has a way to stay cool, make sure you have the proper thermostat in
> your engine to help with cooling. Use a "water-wetter" it will help with
> keeping the engine cooler.
> A hot engine is never good. A proper EFI with todays fuel and a proper
> operating cooling system will help engines to stay alive longer.
>
> Sammy
> GMCless (shhh! lol)
>

>>
>> I did read JimB's blog, and there is a little I disagree with but there is
>> also very little hard information there.
>>
>> As an auto-lab rat from the early 70's (on and off), I can tell you for a
>> fact that at lot of both Jim's and your premise is correct, but some is not.
>>
>>
>> Since the early 70's (at Chrysler Proving Grounds) is has been a stated
>> fact that the carburetors we all know are not a vaporizing or gasifying
>> device. In actual fact, the industry has referred to them as "solid fuel"
>> carburetors for years. While the droplet size does matter for emissions
>> (back when a carburetor could even meet those standards), there was a
>> running game (with a large number of really strange plays) between large and
>> small. Small droplets cold burn faster and the larger more slowly. Not
>> too different than gun powder grain size. Which you wanted depended on just
>> what you were trying to accomplish at that moment. The capability to
>> maintain a stoichiometric over a wide band did not arrive until the EGO
>> sensors
>> got reliable. Even then, the "closed loop" carburetors were not that good
>> at much of anything.
>>
>> Other running issue is: What is gasoline?
>> Even before "reformulating" this was an open question. When we were
>> getting non-indolene test fuels, we always got a report with the
>> carbon/hydrogen
>> ratio. even if this number was in target, we still could only use
>> indolene (a specific chemical hydrocarbon that can be used as motor fuel)
>> because
>> it was the only thing stable enough to give stable emissions values.
>>
>> So, the fact that reformulated motorfuel may have a stoich number that is
>> other than 14.68 is just not an issue. From an SI engine's point of view,
>> there is little change over a significantly wide range. Again, this is
>> just one of the problems that new engine controls manage. Just about all of
>> the engines that have a EGO per bank and a modern ECU, are actually doing
>> a cylinder by cylinder mixture control. This has to happen for current
>> standards. It was not desired in the mid-70s cat cars, because they
>> counted on the rich/lean pulses to keep the cat lit and still provide
>> enough O2
>> for the desired reactions to complete.
>>
>> Then there is the issue that not all the cylinders see the same mixture
>> (the end cylinders often get lean) with any central fuel feed system. The
>> initial charge pressure (present in the cylinder when the intake valve
>> closes) has a lot to do with what is going to happen when the fire gets
>> started. No, all the cylinders of an engine are never the same and less
>> than a wide open manifold only exacerbates that issue by steering the charge
>> mixture in different directions.
>>
>> We live east of the Mississippi and rarely encounter altitudes above
>> 6KMSL, but the coach rolled over the Big Horn on the way to Yellowstone and
>> the
>> coach did not complain. We even had to go around a couple of little
>> four-wheels that could not keep speed up at 9200MSL (according to my GPS).
>> They
>> were all too new to be open loop. And, we still did our regular 9.2 for
>> that journey.
>>
>> So, before you get all fired up to change to a tack-on "fuel injection",
>> decide if it is something you really want to do.
>>
>> As Dick Paterson has been known to say, most carburetor problems start
>> with the ignition. I am not fond of HEI, but it can be serviceable, you
>> just
>> have to be sure you have the spares along. But, you should carry ignition
>> spares in any case.
>>
>> Matt - I'll get down off the milk crate now, I have some passcar work to
>> do today still.
>>
>>
>> --
>> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
>> Electronically Controlled Quiet Engine Cooling Fan
>> OE Rear Drum Brakes with Applied Control Arms
>> SE Michigan - Twixt A2 and Detroit
>>
>> _______________________________________________
>> 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

 

[jerry work]

Jerry, I don't want to open a can of worms, but the longevity of the FITech
unit, with its electronics in a sometimes very hot throttle body, has been
questioned. One of the coaches you sold had a FITech system and suffered a
sudden fuel delivery failure for the new owners on their trip home. What
was the final diagnosis of that failure? There was speculation at the time
about effect of heat on the electronics……….
==============

 

[LarryW]

FYI. I have been running a FiTech now for about 3K miles, and have had two issues, both of which were not really FiTech related. I post this only
because if others run into the same symptoms, they will have a starting point on where to look.

Let me start with what I have. I am running a Cadillac 500 and have had it powered by a Qjet that was stock for the Cad engine, a Qjet that was
altitude compensating, a Port EFI with EBL software, and now the FiTech. Best performance hands down is from the FiTech. My fuel system consists of
25gal fuel tanks. High pressure fuel pumps are in the tanks and controlled by a switch on the dashboard. Once activated by dash switch, fuel flows
through a check valve located at each tank. Check valve keeps fuel from flowing into the nonactivated pump and into the other tank. Fuel continues to
a "T" in the line allowing pressure to build at the Fuel Pressure Regulator. Once calibrated pressure is reached, excess fuel is dumped back into the
front fuel tank, the "reserve" tank. Pressurized fuel then flows through another check valve which keeps fuel under pressure for "hot restart". Fuel
then flows through an inline fuel filter and on to the "dead head" FiTech throttle body.
The system is designed this way with the pressure regulator located on the frame rail at the front tank to keep fuel from going to the engine, heated
up by engine heat, and returned to the tank hot, thereby increasing the chances of vapor-lock.

Now that you know what I have, here are the two issues I delt with when I installed the FiTech. First issue...shortly after the install, the motor
just suddenly started running VERY rich, like I mean AF ratios were in the low 11's, high 10's. Now that was averaging 10.8/1 FA. After looking at
several things, decided to get a Fuel Pressure gauge and check to see that FP was at the spec'd 58lbs. So I let the engine run while I went looking
for the gauge. When I got back I noticed that the FiTech TB was soaking wet with water, and ice cold to the touch. Also found the vacuum line going
to the PCV valve was also cold and wet, as was the "T" in the line and hose that went to the vacuum canister. Disconnected the vacuum line going to
the canister and plugged it. Instantly the engine smoothed out and AF went into the 14's. What I found was the Vapor separator (located in the left
rear wheel well had malfunctioned and was allowing a full fuel tank to bleed raw fuel through the canister and into the TB below the throttle plates.
The change in physical state from liquid to vapor caused the cold TB and condensation on the TB. And most of all caused the excessively rich mixture
as indicated by the AF readout. I now have replaced the Vapor separator and all is well. This issue, not the fault of the FiTech. Who KNEW!!

The second issue cropped up when I would stop for fuel after several hours traveling and a hot engine. The engine would not restart after
refueling...not all of the time, just intermittently. When you turn the key on with the FItech, yours should hear a clicking sound coming from the
TB. That is the software opening the throttle plates slightly and squirting some fuel into the intake manifold for a clean start. When I had the no
start condition, I was not hearing the clicking and not seeing the throttles click briefly open. Apparently there is a sensor of some kind in the TB
that sensed fuel presence. No fuel...no squirt. Somehow a bubble of air or maybe fuel vapor gets caught as a bubble in the TB and since it senses no
fuel...no start. To start, I take a adjustable wrench, and crack open one of the fuel inlets to let the bubble out. Instant start and no issues until
the no start happens again. I think this is a kind of vapor lock happening in the TB after a hot run. This may well be a result of not having a
return line to the tank. When FP exceeds the 58lbs, there is no way to bleed off this pressure. So, I'm working on a solution to this..not sure what
it will be.

Again, I post this so that it might help anyone experiencing these same symptoms and for people to take preventive measures. Hope this helps someone.
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.