RE: [Chrysler300] Carter AFB - Edlebrock carb help needed

["'Henry Schleimer' henry.schleimer@xxxxxxxxxxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx>]

Just thought I'd pass on my experience with vacuum gauge tuning.  I did this
with my 78 Australian Valiant with a 265 Hemi six and two barrel Carter not
long after I bought it around 15 years ago.  Got the best idle vacuum and
thought everything was sweet!

 

I was then involved with setting up Queensland Transport's random on-road
emissions testing where Inspectors would pull over cars and do an idle check
for HC and CO.  No fines - just educational to help combat pollution.  As
part of trialling the mobile 4 gas analysers we were using, I had an
Inspector test my Val.  I found the emissions were off and more surprising
was the significant effect that just 1/16 of a turn of the idle screw would
have.  That small change didn't show up on the vacuum gauge.  The car ran
better after that and I haven't touched it since.  My experience was that
vacuum tuning gets you in the ball park but having a mechanic put a probe up
your exhaust pipe is a small cost for savings in fuel, reliability and peace
of mind.

 

Also, my previous Val had a two barrel Carter on a 318.  I tossed the Carter
for a new 4 barrel Holley along with other mods.  (4 barrel Carters were
rare as hens teeth over here.)   I had that dyno tuned and found the jetting
was set up rich straight out of the box.  Obviously, dyno tuning can give
air/fuel ratio throughout the rev range and under all types of load - not to
mention spark timing for max power.  Back then, the testing and fitting new
jets cost me $75 when the carb cost me $350 - so it was a relatively good
investment.

 

For my 300C, I have religiously followed the factory manual for carb set up.
But once it is going (and I have confidence my transmission rebuild won't
blow up) I'll probably still get it dynoed even if it is running well.  Be
interesting to see if it really has 375 HP!

 

All the best from Henry in Brisbane Australia where it is now Spring and 24
degrees C.

 

 

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of 'John McAdams' clafong@xxxxxxxxxxxxx [Chrysler300]
Sent: Thursday, 4 September 2014 3:12 AM
To: 'Michael Moore'
Cc: 'Rick Vitek'; 'Chrysler300@xxxxxxxxxxxxxxx'
Subject: RE: [Chrysler300] Carter AFB - Edlebrock carb help needed

 

  

Michael:

 

Back in the fifties, I used this tip on my first car, a flathead Plymouth
six with 2 carbs.  When adjusting the idle screws, I watched (or felt) the
front edge of the open hood to see when it was shaking or steady.  You have
the advantage of the long hood pivoting from the cowl.  Sometimes I held my
forehead or temple against the edge of the hood.  

 

>From Big John Mc Adams

(In SoCal)

 

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of Michael Moore mmoore8425@xxxxxxx [Chrysler300]
Sent: Monday, September 01, 2014 7:18 PM
To: Michael Moore
Cc: Rick Vitek; Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Carter AFB - Edlebrock carb help needed

 

  

Rick, I just watched a video about how to adjust idle mixture screws using a
vacuum gauge, so I will try that.

Thanks!

Mike Moore

300H

 

On Sep 1, 2014, at 12:54 PM, Michael Moore mmoore8425@xxxxxxx [Chrysler300]
<Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

 

  

Rick,

Thank you for your informative note. I have religiously followed the
workshop manual to adjust my carbs (300H). Many years ago (I've owned it
since 1966) I had no problem tuning it up. In recent years, it sat idle for
a number of years and I finally had the time to get it back on the road. I
was not happy with how it ran, even less so with how it stopped. 

I fixed the stopping problem then worked on the running problems. 

A friend who is most impressed with his mechanical skills spent some time
helping me. That got a bunch of linkages bent up. I later replaced the
distributor which helped immensely and had a top shop rebuilt the carbs with
all new linkages. Suspecting the damper and timing mark, I had it rebuilt. I
also adjusted the valves hot,and running,  measured them, and for reference
later checked them cold and found ca .002  difference between hot and cold. 

Dwell is correct, timing is correct-but I still do not like the way it runs.
I have followed the work shop procedure several times, always dissatisfied
with the results, My professional mechanic (not the genious who bent up the
linkages) , who owns a Corvette, also with dual AFBs  says its just because
of the gasoline. 

One thing I am unsure of is tuning the 4 idle screws and looking for rpm
increase or decrease, I can sometimes turn a considerable amount and not see
it go up or not. How do you use a vacuum gauge for that?  

 

Because we have owned the car so long, and do enjoy it, I have been
wondering about installing a single 4-barrel carb on another manifold for
normal driving-but then what? 

Why would I ever install the 2x4 manifold again? 

 

1. What would you do.

2. What do you use the vacuum gauge to adjust the carbs. (I am using a tach
only)

Thanks,

Mike Moore

300H 

 

On Sep 1, 2014, at 12:28 PM, 'Rick Vitek' rpvitek@xxxxxxxxxxxxx
[Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

 

  

With respect to Q1, are you sure if it's too much fuel or not enough? Mark's
post is more likely, namely it's a vacuum management issue. Lower engine
rpm's and thus less vacuum combined with braking (and thus with power brakes
actuating and affecting vacuum).

Q2: Putting a new Holley carb on it may fix it, as might putting on a new
Edelbrock. There is nothing intrinsically better about the Holley design (
though a lot of aficionados for either would love to argue this point). In
either case you'd be putting on a new carb where everything is adjusted to
the proper spec's and working right. After all, the AFB has served well on a
lot of Mopars through the years.

The following is not directed at you or anyone in particular but rather
hopefully provides a background for looking at any carb problem. A look at
the history of carb development shows system after system added on to
correct limitations of the basic design. For example in response to a
problem of stalling during hard cornering Holley added the "cathedral" bowls
to prevent fuel starvation. So what was a simple mechanical system in the
twenties morphed into a complex system by the seventies, probably the most
complex part of the engine accessible to the operator. By that I mean your
average owner wouldn't tell himherself "I think there's a problem with the
tranny so I'll drop the pan and start fiddling around" or " the steering is
not right so let me open the gear box and see if anything pops out". Your
average operator with an engine problem is however willing to pull the air
filter, stare at the carb, and saying something like " I don't think the
choke is pulling off soon enough so if I just bend that linkage arm the
choke will be more open and the problem solved". Since its an integrated
system that bending of linkage may open the choke but also affect something
else in the carb. Thus a lot of carbs out there may have been tweaked since
their latest rebuild in ways they were not intended to be tweaked but which
the operator/mechanic thought was a good idea at the time. Worse yet, some
have been "rebuilt" without checking to see if the linkage has the proper
dimensions/operation. Add to this a thousand gallons of gasoline (with its
contaminants) that are pumped through that carb (and its close tolerance
parts) per year. Sometimes it's as simple as a particle blocking a port. The
problem however often involves degradation of multiple systems within the
carb. As such it often involves going back to first principles or
epistemological analysis to diagnose, namely how do we know what's working
right. Last year I started working on a ram engine car that was hard to
start, often stalled, and gave underwhelming performance when running. The
car was advertised as having recent professionally rebuilt carbs - and I
think they were. By the time I went through using the factory specified
procedure for setting up the throttle linkage from the accelerator pedal
through the final connection to the carbs, setting the entire carb linkage
through the procedures given by Carter, new tune up parts and adjustments,
adjusting both carb's mixture and idle, replacing all vacuum tubing, and
making sure the tubing was connected to the right ports I had an engine
running just great. After each procedure the car ran a little better but no
one procedure "fixed" the problem. When I see someone ask "how many turns
out is this mixture screw supposed to be?" I think back to the service
manual. If there was a hard number it would be in there. Rather you can
start at a certain point but then have to adjust to the particular engine
you're working on due to e.g. manufacturing tolerances and wear. A lot of
guys may be able to use their ears to tell how an adjustment affects rpm's
but I have to use both tachometer and vacuum gauge to see the effect. This
is especially true on multiple carb set ups where you have to go back and
forth several times to get them balanced.

I realize this doesn't solve your problem. Perhaps, based on your particular
setup you could start by putting a vacuum gauge on the carb and see the
response when going through various scenarios such as 2000 rpm to fully
closed throttle, brake actuation etc.

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of Mark Lindahl mplindahl@xxxxxxxxxxxxx [Chrysler300]
Sent: Monday, September 01, 2014 12:25 PM
To: christopher; Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Carter AFB - Edlebrock carb help needed

Christopher,

I am having the same problem with a Carter AFB 3256SA in my '63 Chrysler 300
conv. Sudden stops can cause the engine to stall. Also, a quick slowdown
with a right turn causes engine to nearly stall. I increased idle and this
helped a bit, but I don't think this is the complete solution.

I find that when I downshift before making a quick right turn, there is less
of a stalling problem. When I have the trans in neutral, the problem is
worse. This leads me to believe that as long as the wheels are turning the
engine (in a downshift condition), the proper amount of fuel is getting to
the engine (under load).

My 1st guess is that some of the small carburetor ports may be semi-clogged
and the proper amount of fuel gets sucked in the engine only under high
vacuum (load conditions)? 

Let me know your thoughts.

300ly,

Mark Lindahl

On Monday, September 1, 2014 6:35 AM, "christopher
thelastbestgenius@xxxxxxxxxxx [Chrysler300]"
<Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

Q1. Motor with a 60s/300 style 4bbl Carter AFB type carburetor on it - brake
real hard, near panic stop, and motor stalls as if gas/fuel flooding/pouring
out of carb float chambers and into the carb/motor guts/intake, and it
richens motor too much so it stalls - is this common with thyis type carb in
this situation, AND IF SO IS THERE A CURE??
The same carb is now sold as an Edlebrock 
Q2. - tuner guys have said put a 4bbl Holley on motor to cure it instantly -
DOES THSAT SOUND TRUE?

Christopher in Australia - 1st day of spring, and/but just rained hail and
sleet outside. And for US300ly grain farmers, many Southern Australian
winter grain farmers badly need rain, plus savage frosts a while back
totally ruined many crops before they even ripen

I see there was a seemingly nice red 300C on ebay last week, at around $57k,
no takers. I realise 300G looks is a maybe acquired taste, so that one
selling in the $60ks was not too surprising given the sad situation re both
its's owners, despite it normally should have bought maybe a 25% higher
price than usual due to it's known quality/standard?.\
And in the past, was $60s to 70ks a fair/good/average figure for real good
'57-61 300 Coupes, so maybe not much changed. But against that one of the
bigger Market Report email/websites, just posted few days ago, that now
annual Monterey Sales just ended, averaging all big US auction
Sales/Results, prices up around 30% - not seemingly with 300s though.
Anyhow, key thing is enjoy driving them, as what they worth only any good if
you selling!!

[Non-text portions of this message have been removed]

 

 

 





[Non-text portions of this message have been removed]



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Posted by: "Henry Schleimer" <henry.schleimer@xxxxxxxxxxxxxxx>
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