Carburetor EGR port question - Page 3

The explanation is in the post you're responding to.
 

Simpson wrote:

I don't know that particular carb, but have seen that kind of failure
before.  When I saw it it was a gasket in wrong or the wrong one in so a
notch in the base plate was covered when it was supposed to be open.

The other times I have seen the base plate in upside down.  There are
notches in some that need to be on the carb side, not the manifold side
and if folks don't know this, the plate can be in wrong.

I would figure the port you are using was blocked or it would have one
or the other types of vacuum.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08.  Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com

Mike Romain wrote:

Could this 'base plate' be a one inch aluminum spacer with a single
manifold vacuum port? Or are you referring to the actual throttle
portion of the carb? That would be kind of hard to put in upside down.
In any case, as in my reply to MasterBlaster, I suspect a leak in the
canister purge line, which enters the carb just above the closed
throttle plates, same as the EGR port.


It's brand new, straight from the Holley factory, after sitting on some
shelf for about 20 years or more.

Simpson wrote:

Yes it could.  Sometimes the kits come with multiple types of base
gaskets with different holes or slots.

Or are you referring to the actual throttle

There is an easy test for that though I don't think it can be the
trouble unless you were measuring the vacuum downstream vs at the carb
nipple, just pinch the line closed.

Mike Romain wrote:

Mike, I solved the problem. See my detailed reply to BigIronRam in this
thread.

Thanks, for the help. You were on the right track as far as the port
probably being blocked goes. Whatever the reason, it just wasn't
developing EGR vacuum characteristics and would not even make it to 2
pounds at 2,000rpm.

Simpson wrote:


Your response was to ignore the advice given. The suggestion was made that
the EGR was designed to run off the very low vacuum port. From there it
goes to a vacuum amplifier which uses the low vacuum signal to control the
EGR using vacuum coming from intake manifold. If I understood your
response - you ignored that advice  and hooked it up in a different way.

    The low vacuum plus amplifier may or may not be how your engine vacuum
lines are supposed to be configured. But it does sound like the carb was
designed to work with that configuration. Is there an under-the-hood
vacuum line diagram?

-jim






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jim wrote:

My response was to investigate what a vacuum amplifier was and then to
determine that the EGR system on the 87 Dakota V6 did not incorporate one.


And that is *all* that it was... a suggestion.

  that

But not in this case.

I hooked up the EGR valve the way it was hooked up stock. There is no
vacuum amplifier. The vacuum hose from the EGR port on the carb goes
directly to the CVSCC (coolant vacuum switch cold closed) which prevents
the EGR system from kicking in when the engine is closed. The vacuum
line then goes directly to the EGR valve.


You're starting to repeat yourself.


I hooked it up in such a way that passed the smog inspection.


Now you're getting it.


It may be that the *carb* was designed to work that way, but the EGR
system on my truck was designed to to work without a vacuum amplifier.

I made it clear in the thread that the mixture control solenoid for the
original, stock carb can longer be purchased and that the carb I am
working with is the non-feedback version of that carb. I also made it
clear in my last post to Mike Romain that I modified the carb to work
like the original as far as the EGR function goes and that the mod was
successful.


Of course there is. There is also one in the shop service manual.


Are you the hall monitor for this group? Do you go around busting people
for not following the advice of others to the letter? If so, you have
too much time on your hands.



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Simpson wrote:

Your reply made no mention of that. That is you completely ignored the
advice and didn't explain why you ignored it until now. You didn't even
give a hint that you comprehended what was said.




Maybe - Maybe not. How the hell would I know.



When people fail to indicate they understand the advice the tendency is to
repeat it. No??


Then why are you trying to do additional modification? You've made a half
dozen posting since you passed the test asking for help with
modifications. What's that all about?



You still don't "get" that when you fail to provide adequate information
the reader has no choice but to guess what the actual facts are.


But given that you now have a different carburetor the range of vacuum
coming from the EGR port will not be exactly the same as the original and
it is possible that the way it was hooked up in connection with a vacuum
amplifier might give you better performance. The EGR affects the mixture
that the carb delivers. If the flow thru the EGR is not in synch with the
carb mixture controls you may not be getting optimum mixture at all the
different possible engine loads and RPMs. So the original advice to hook
the EGR thru a vacuum amplifier still may have produced better results
than you got.



You implied that you replied to the advice given. You did not reply to
that advice you ignored it completely. You didn't even give the slightest
hint that you understood what the advice was.  Since my crystal ball is in
the shop for repairs this week - I thought maybe you didn't understand the
advice and perhaps maybe you would want to be aware of that. But
apparently you're not interested.

-jim




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wrote:


He has already stated that with the replacement carb installed the HC
emissions are barely within limits.


He has already explained that he reconfigured the vacuum slots to match
the old carb.  And what's to say that his current EGR valve is
calibrated to be used on a system that employs a vacuum amplifier?
Where does it end?   It's a 21 year old truck.


When you say mixture associated with carburetor (or any fuel metering
device), It's assumed you mean the air/fuel ratio.  Exhaust gas is
neither air nor fuel, it's supposed to be inert.  EGR doesn't alter
air/fuel mixture, it displaces it.


He's not getting optimum mixture because he's using a lean burn carb in
a non lean burn application.  But what do I know, I only worked on them
every day in a dealership in the late 70s.


And if there's an underhood inspection involved with the emissions test,
he gets an automatic fail.

aarcuda69062 wrote:

The 15 mph test was barely within limits. The other was well within
limits.



Not a very difficult thing to check if you have a vacuum gauge.



How is "displace" different than "alter" ? Do you think the engine is
concerned with semantics?


You are revealing how little you know. Besides his engine is new enough to
be beyond some of the stupidity of the 70's lean burn applications. The
reality is the EGR will affect mixture on a carb because it does affect
airflow. Even some of your statements seem to be claiming that it was not
too lean before the EGR was hooked up but now after it is.
    Now if the EGR is the only thing different from the failed test to the
passed one (a doubtful theory in itself). He may simply not need as much
EGR at 15 mph than he is getting with his current setup. That might
entirely account for the higher HC. The carb was designed to work with an
EGR that followed venturi vacuum - I'm not saying it will work better if
configured like that but it does seem likely. Given that he doesn't have a
standard setup. The only way to find out is to experiment.


He will fail for not having the OEM carb?


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wrote:


And he wasn't satisfied with "barely."
I wouldn't be either.
The frickin cut points are so loose that if it's not below 50% of cut
point, something isn't right.
 

Okay, publish the vacuum specs for both types of EGR systems.
That ought to help him considerably.
 

It's the twenty first century Jim, the old beliefs that you're
subscribing to here have been long refuted.
 

Main Entry:
dis?place
Pronunciation:
\(?)dis-?pla?s, di-?spla?s\
Function:
transitive verb
1 a: to remove from the usual or proper place; specifically : to expel
or force to flee from home or homeland <displaced persons> b: to remove
from an office, status, or job cobsolete : to drive out : banish
2 a: to move physically out of position <a floating object displaces
water> b: to take the place of (as in a chemical reaction) : supplant

Main Entry:
al?ter
Pronunciation:
\?o?l-t?r\
Function:
verb
transitive verb
1 : to make different without changing into something else
2 : castrate, spay
intransitive verb
: to become different


 > Do you think the engine is concerned with semantics?

Do you think a boat floating in water makes the water different?

Your wet sidewalks cause rain fan club membership card is in the mail.

Really?  The results of his third test show differently.


Couldn't figure out how to fix them, 'eh?


Not even close to plausible.


Cite?


Gee, I'm pretty sure there was a carburetor change in there.


It might if the CO weren't so low.
I will admit to not having fully realized that he connected the EGR to
the vacuum fitting for the spark transducer which well would cause an
over EGR condition.  Should have run like crap at cruise though...


And he has since modified the carb and tested it configured with ported
vacuum with positive results.


Not necessarily due to there no longer being any service parts.

I don't know what your problem is, Simpson has demonstrated amazing
ingenuity, intuition and desire to learn and understand.

aarcuda69062 wrote:

But the point was that only under certain load and RPM  it was well within
limits.



The reason they introduced the vacuum amplifier was not because they
changed the way the EGR worked but because they changed the location that
the vacuum signal that operated the EGR came from. The EGR valve for his
vehicle probably was the same for a 10 or 15 year period. During that time
they had all sorts of different carbs and vacuum line configurations.
    The signal from venturi vacuum was to weak to operate an EGR valve in a
reliable way so it needed to be amplified and then the same old EGR could
be used. The reason it was  tied to the weaker venturi vacuum was that
would allow for more  accurate metering of air and fuel under a  wider
range of operating conditions. The feedback carberator wouldn't need that
because the feedback system itself would be able to compensate for any
changes in airflow that affected the air/fuel mixture.
    As for the Chrysler lean burn crap - that was easy to fix. What was so
incredibly stupid was it took Chrysler engineers 10 years and near
bankruptcy to figure out how to fix it.

-jim




Air fuel mixture is controlled by the flow


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wrote:


No one drives at only 15 and 25 miles per hour.  There is no data for
other speed ranges so, the word "only" is a bit disingenuous.
 

It couldn't possibly be.  His was the first year of production for both
the chassis and the engine, the year following his was throttle body
fuel injection and used a SMEC controlled pulse width modulated solenoid
and back pressure transducer to control the EGR.


No they didn't. One year only.  4 cylinder or six cylinder.


That was Chrysler's way of doing it.  That's all that can be said.


Love to hear about it some time.  Hope you research it better then your
claims about the 10-15 year spread where they used that exact EGR
valve/scheme on a vehicle that was produced in that configuration for
only one year.


That's the way innovation is.

aarcuda69062 wrote:


For someone who claims to know something that is as good as saying you
don't. I didn't say chrysler used the same engines for all those years I
said the EGR's were all pretty much the same in that era. The means of
controlling the vacuum, which determined how much exhaust gas was
delivered and when it was delivered is what changed depending on make,
model and year.
    That was the purpose of vacuum hose configurations, vacuum amplifiers or
transducers and different vacuum ports. The difference in the valve itself
had more to do with how they fit on the engine rather than how they
behaved.

    At any rate EGR clearly has a huge effect on NOX emissions and does
completely change the way air and fuel burn inside an engine. That mains
the entire way the engine is tuned needs to change to accompany the
changes that EGR creates. For the most part EGR is beneficial. It is a lot
like getting an octane boost (at no extra cost) and does allow for better
fuel economy as well as overall better emissions *if* the engine is tuned
to accommodate the changes in burn characteristics. That means changing
air/fuel ratio as well as timing. The modern vehicle's computer takes care
of all of that for you so yes you can get along quite nicely with any
knowledge of it.

-jim


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wrote:


That's hilarious coming from someone who's above statement describes the
EGR as metering air and fuel.


Must be why they all had the same part number (not).


Now you're getting it.
Did the 87 Dakota V-6 use a vacuum amplifier?


Sounds like something the guy at the junkyard would say.
 

Never said otherwise.


Which is not the same as asserting that the EGR changes the air fuel
ratio.

aarcuda69062 wrote:

Ultradrive innovation?

In article
 beerspill@whoever.com wrote:

jim wrote:

You can't possibly realize how quickly this situation has progressed
since I first posted. I stopped mid-post in my 3/21 4:19pm reply to Mike
Romain in order to pull the carb, tear it down and make modifications to
the ports in the throttle body based on the ongoing suggestions that I
was given and my own very intimate knowledge of this carb and it's
various configurations. I am doing this work as I see fit based on my
understanding of the situation at any given moment. I am also trying to
reply to all posts and explain the work that I have done, the reasons
for doing it and the results I have gotten.

I'm sorry if I don't do it in a way that you deem proper.


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Simpson wrote:


I don't particularly care much how you do it. I was trying to empress upon
you that the advice you get is only as good as the information you supply.
For instance why is it you changed the carb in the first place? And how
much have you driven with the new one? If someone cared, they might guess
that the old carb was running very rich and you haven't driven very many
miles on this one. It may pay off to just drive it a few hundred miles. It
may take a while to recover from whatever was previously wrong. Also
fiddling with the idle mixture is not likely to help much. When your going
down the road the throttle is usually open enough that the idle circuit is
no longer doing anything.

-jim




vacuum

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jim wrote:

Actually, I'm doing quite well, thank you. I appreciate your suggestion
about advancing the timing. Perhaps you should limit your posts to
asking questions and making suggestions instead of trying to correct
what you seem to regard as my inappropriate posting methods in my
communications with others.


vacuum

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Chuck Norris can fool all of the people all of the time and Chuck Norris
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