[Cadillac] 1959 cadillac Carter AFB
starcom...@yahoo.com
Trying to figure out once and for all how to set the idle speed , mine has factory AC and I was using the round barrel nut by the firewall . The motors manual says to use the center big screw on the card to set the speed and adjust the 2 smaller screws for the fastest idle? Was using the barrel nut by the firewall to idle up or down incorrect? If the center screw on the carb should be used to idle up or down then what is the purpose of that barrel nut on the bracket, by the firewall.. I had the carb rebuilt about 5 years ago, lately the car dies when I run it down the road and go into a sharp left hand turn... it dies completely,... It does not die when I stop at a stop sign or go into a sharp right turn.... Was thinking the floats set too low??? It never did that before , and the carb doesnt even have 2000 miles on it, as I only drive the car on Sundays..... once a week..... other than that, the carb works great, no flooding and no hesitation ......... Was thinking perhaps since I am usng the barrel nut by the firewall to set the idle speed, perhaps the linkage is shifting when I make a sharp left turn from a speed of about 40 mph... I dont want to mess with the floats if it is a linkage or idle adjustment issue................
Any ideas , would be helpfull....
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redcad59
The *barrel nut on the bracket* is an IDLE SPEEDUP VACUUM control whose job is to
open the throttle slightly at STARTUP, or anytime the vacuum drops low enough to
allow spring-pressure inside the vacuum valve to push the throttle control.
Correctly operating original '59 390 systems suggested slight throttle boost at
startup as well as anytime the engine was about to STALL. This is only adjusted AFTER
all other carb adjustments and with the engine OFF. Has nothing to do with
factory A/C, as that was controlled by a separate VALVE mounted on the Carb.
Besides all of that, I used the SHOP MANUAL procedure as you have described, and found it
probly worked just fine for relatively lightly used vehicles with Leaded and non-Ethylated fuels.
The first strike against the procedure is that virtually all of the carbs for-which-it-was-originally-written have aged significantly and are prone to internal leakage of fuel and/or vacuum.
The Second strike is in regards to modern fuels - i.e. Unleaded & Ethanol enhanced.
The SHOP MANUAL method still *works*, it just doesn't work nearly as well.
I rebuilt my original '59 CARTER AFB about 5 times and retuned it countless more, before trying out a new (circa 2001) EDELBROCK 1406 which was based on exactly the same design as the AFB.
That made IMMENSE improvement, and after retuning/re-tweaking to get to her *sweet spot* I had solved most of my performance problems. The rest of the probs were only resolved once I realized in 2009 my engine was sorely in need of a full rebuild.
In regards to your *original* problem that led you to this point, I think you are on the right track with your 'float' theories. I do not suspect linkage probs.
(BTW, I must recount a portion my personal story with my original '59 AFB, as it is remotely
possible it could have occurred in this case as well.)
[Are your fuel bowl BAFFLES in place? Mine were missing from my
'59 AFB due to bonehead mechanics before me. The two baffles or baffle-plates
sit 'vertically' right in front of the secondary metering jets in the fuel
bowl and reduce the tendency of the fuel to 'slosh' towards the rear of the
carburetor when the car suddenly accelerates. This would otherwise cause the fuel
level to rise suddenly over the secondary jets, massively enriching the
mixture, tending to flood out the secondaries with excess fuel. Likewise, they reduce
fuel sloshing to the front of the carburetor in sudden braking maneuvers, and moving the
enrichment process forward to the primaries, flooding them out. This is what my '59
was doing for the first year until I figured out what the heck was going on! ]
-----Original Message-----
>From: starcom...@yahoo.com
>Sent: Sep 30, 2013 10:56 AM
>To: classicca...@yahoogroups.com
>Subject: [Cadillac] 1959 cadillac Carter AFB
>
>
>
>Trying to figure out once and for all how to set the idle speed , mine has factory AC and I was using the round barrel nut by the firewall . The motors manual says to use the center big screw on the carb to set the speed and adjust the 2 smaller screws for the fastest idle? Was using the barrel nut by the firewall to idle up or down incorrect? If the center screw on the carb should be used to idle up or down then what is the purpose of that barrel nut on the bracket, by the firewall.. I had the carb rebuilt about 5 years ago, lately the car dies when I run it down the road and go into a sharp left hand turn... it dies completely,... It does not die when I stop at a stop sign or go into a sharp right turn.... Was thinking the floats set too low??? It never did that before , and the carb doesnt even have 2000 miles on it, as I only drive the car on Sundays..... once a week..... other than that, the carb works great, no flooding and no hesitation ......... Was thinking perhaps since I am usng the barrel nut by the firewall to set the idle speed, perhaps the linkage is shifting when I make a sharp left turn from a speed of about 40 mph... I dont want to mess with the floats if it is a linkage or idle adjustment issue................
>
>
>
>
Ron Threadgill
'Miss Scarlett' - 1959 Cadillac ElviSeville DeVilleDorado CoupeVertible Fleetisman D'EleBroughamWood VRX Hybrid
http://home.comcast.net/~amthreadgill/
or
http://www.pipeline.com/~rthreadgill/
Cadillac & LaSalle Club - Central Virginia :
www.CentralVaCadillacLaSalleClub.org
MARCEL THORIMBERT
down & allow gas in, making the float heavier.
Switching to an all brass float eliminates this problem.
There are some paper catalogs [Standard Motor Products, etc.]
that use to list the weight of new floats. They also sold a hanging
scale with an alligator clip to weigh the float.
Subject: [Cadillac] 1959 cadillac Carter AFB
Trying to figure out once and for all how to set the idle speed , mine has factory AC and I was using the round barrel nut by the firewall . The motors manual says to use the center big screw on the card to set the speed and adjust the 2 smaller screws for the fastest idle? Was using the barrel nut by the firewall to idle up or down incorrect? If the center screw on the carb should be used to idle up or down then what is the purpose of that barrel nut on the bracket, by the firewall.. I had the carb rebuilt about 5 years ago, lately the car dies when I run it down the road and go into a sharp left hand turn... it dies completely,... It does not die when I stop at a stop sign or go into a sharp right turn.... Was thinking the floats set too low??? It never did that before , and the carb doesnt even have 2000 miles on it, as I only drive the car on Sundays..... once a week..... other than that, the carb works great, no flooding and no hesitation ......... Was thinking perhaps since I am usng the barrel nut by the firewall to set the idle speed, perhaps the linkage is shifting when I make a sharp left turn from a speed of about 40 mph... I dont want to mess with the floats if it is a linkage or idle adjustment issue................
Any ideas , would be helpfull....
redcad59
Good point about the float material.
My originals have always been brass, and even the 'drop-in' replacement EDELBROCK 1406 had brass floats. It would really be unusual to find something else in there, but it IS POSSIBLE.
However, if you should need original brass floats, I have quite a few spares, so just let me know.
-----Original Message-----
>From: MARCEL THORIMBERT <marcelth...@hotmail.com>
>Sent: Sep 30, 2013 2:28 PM
>To: "classicca...@yahoogroups.com" <classicca...@yahoogroups.com>
>Subject: RE: [Cadillac] 1959 cadillac Carter AFB
>
>Some floats are a composite material, that eventually breaks
>down & allow gas in, making the float heavier.
>Switching to an all brass float eliminates this problem.
>There are some paper catalogs [Standard Motor Products, etc.]
>that use to list the weight of new floats. They also sold a hanging
>scale with an alligator clip to weigh the float.
>
>
>To: classicca...@yahoogroups.com
>From: starcom...@yahoo.com
>Date: Mon, 30 Sep 2013 07:56:07 -0700
>Subject: [Cadillac] 1959 cadillac Carter AFB
>
>
>
> Trying to figure out once and for all how to set the idle speed , mine has factory AC and I was using the round barrel nut by the firewall . The motors manual says to use the center big screw on the card to set the speed and adjust the 2 smaller screws for the fastest idle? Was using the barrel nut by the firewall to idle up or down incorrect? If the center screw on the carb should be used to idle up or down then what is the purpose of that barrel nut on the bracket, by the firewall.. I had the carb rebuilt about 5 years ago, lately the car dies when I run it down the road and go into a sharp left hand turn... it dies completely,... It does not die when I stop at a stop sign or go into a sharp right turn.... Was thinking the floats set too low??? It never did that before , and the carb doesnt even have 2000 miles on it, as I only drive the car on Sundays..... once a week..... other than that, the carb works great, no flooding and no hesitation ......... Was thinking perhaps since I am usng the barrel nut by the firewall to set the idle speed, perhaps the linkage is shifting when I make a sharp left turn from a speed of about 40 mph... I dont want to mess with the floats if it is a linkage or idle adjustment issue................
>
>
>
>
>
>Any ideas , would be helpful....
>
>
Ron Threadgill
'Miss Scarlett' - 1959 Cadillac ElviSeville DeVilleDorado CoupeVertible Fleetisman D'EleBroughamWood VRX Hybrid
http://home.comcast.net/~amthreadgill/
or
http://www.pipeline.com/~rthreadgill/
Cadillac & LaSalle Club - Central Virginia :
www.CentralVaCadillacLaSalleClub.org
starcommand
From: redcad59 <redc...@pipeline.com>
To: classicca...@yahoogroups.com
Cc: starcom...@yahoo.com
Sent: Monday, September 30, 2013 10:34 AM
Subject: Re: [Cadillac] 1959 cadillac Carter AFB
redcad59
First of all, DO NOT USE THE SHOP MANUAL recommended methods !!!
The bit in question that I called the *IDLE-SPEEDUP-VACUUM* is more correctly
referred to in original literature as the *THROTTLE-CHECK-VALVE*
In section 10-18 (pp.284) under *THROTTLE RELAY AND CHECK VALVE* The pic/diagram shows
a detail of the [ TCV ] valve and associated bits.
Immediately below that is:
b. INSTALLATION
Which then refers you to Notes 20d, 27d, and 34f for TCV adjustment.
all 3 of these subsection notes are identical in content and recommend that
you put on the parking/emg/foot brake, shift to a driving gear, adjust the 'barrel-nut'
and then ***OPEN THE THROTTLE FULLY*** for a moment to allow vacuum drop and subsequent
TCV valve action to commence. Whereas this is may have made sense back-in-the-day, it is
patently ridiculous to consider FLOORING the throttle of any vintage 300+ hp engine without some
sort of movement intended, and only the footbrake as a restraint. The intent of the method is
to test whether the engine reaches a stall condition after vacuum drops suddenly.
I can personally testify that the SHOP MANUAL method WON'T WORK in any case, as the
'vacuum nipple in the intake manifold with a small pin hole on top of it' is specifically
made to METER vacuum/air-flow so that the TCV doesn't activate/de-activate TOO QUICKLY.
By design, IT IS NOT SEALED.
The pinhole restricts airflow greatly, preventing the TCV from slamming open & shut during ordinary
driving. In fact, the TCV won't really do much unless vacuum drops for A COUPLE OF SECONDS!
This would require one to hold the engine at full throttle for a few secs, while carefully
observing the TCV. I suspect one would have more bigger problems than the TCV to worry about
after such a test.
SO ..., once you have confirmed that you have full manifold vacuum at the rearmost 'nipple' fitting of the
intake manifold, you will run a single vacuum line of your choosing to the TCV and then
fire up the engine to see if the TCV *retracts* its little pushbutton. With engine still
running at operating temp, disconnect and reconnect the vacuum hose repeatedly to confirm
that the 'button' is indeed moving in-and-out reliably. You *may* need a replacement valve,
since most folks do. Barring replacement, set your engine idle as directed and note how
the idle speed changes (or doesn't) with respect to the TCV activation. Play with the
barrel-nut for a bit and become familiar with how it moves/adjusts. I would then roughly
duplicate the method from the SHOP MANUAL in regards to adjusting the *IDLE-SPEED-UP-CONTROL*
for the A/C. These are immediately after the aforementioned TCV notes (20e,27e, and 34g respectively)
Ignoring the A/C specific instructions, and with the car *parked/braked* then shifted to a driving gear,
then unplug the vacuum hose and adjust the barrel-nut to achieve approx. 900 ~ 950rpm then reconnect
the vacuum line and assess your work. Re-adjust any time you feel the need.
*ALWAYS* be very careful when performing this sort of car-in-gear work !!
Have a *helper* if at all possible, behind the wheel to kill the engine quickly or to perform
other safety type tasks in the event that Murphy is lurking...
starcommand
redcad59
REPLIES BELOW
-----Original Message-----
>From: starcommand <starcom...@yahoo.com>
>Sent: Oct 1, 2013 9:56 PM
>To: "classicca...@yahoogroups.com" <classicca...@yahoogroups.com>
>Subject: Re: [Cadillac] 1959 cadillac Carter AFB
>
>Jimminy Christmas!
SORRY 'BOUT THAT ! - IT'S ALWAYS MORE COMPLICATED THAN ONE WOULD EXPECT.
>
>I got it to work...
>
>Connected the pin hole nipple to the TCV valve and the pin does move back and foth depending on the vacuum....
I tried to adjust the barrel nut so it didnt maintain too high of and idle when you jabbed the accelerator....
I can't believe it but in the 8 plus years I have owned the car , I never knew that was its true function...
I was using the barrel nut to idle the carb up when that really was the wrong way to set the idle....
When I start the car now, it idles up then the idle comes down, is that the way it is suppose to be??
YES. That's exactly the way it's supposed to be and you adjust the barrel-nut primarily to optimize your STARTING, and
then it will automatically reduce your STALLING. Like you, and probly just about everybody else, I also used it to set
the BASE IDLE SPEED, but that's not the intent. *IN THEORY* you would use the SHOP MANUAL and gently adjust the AIR SCREW and
IDLE MIXTURE screws repeatedly until you got the idle speed and vacuum readings expected. Again, that was fine 50+ YEARS AGO, but
everything has likely aged or changed since then, especially the FUEL. You probly still CAN get a decent result this way, and perhaps
it's the ONLY WAY since you have a rebuilt orig.carb. I spent so much time & effort rebuilding & retuning mine (YEARS, actually)
that I came to the realization that something must have changed to prevent the orig.method from working EVENTUALLY.
The new Edelbrock AFB of same type was the answer for me. BTW, I still do use the TCV along with the newer AFB.
>
>Only thing is now, I really had to turn the big center idle screw out to get it to idle better without the car dieing... and....
the carb is really making that whistling noise somewhat, even when I put the air cleaner housing back on.
>I even got the AC idle up to engage and idle up too,even though I need a new compressor..a little PB Blaster on the shaft
and 3 in one oil also solved the stuck ac throttle idle up shaft.on the carter carb....
>
>Do I have to live with the whistling noise now that the carter carb and idle ups are working the way it should be?
>??
>Before I was using the barrel nut to idle the car up so I had the carter center screw in further so it wasnt whistling.....
Haven't taken it out on the street to see how it performs now..... just hope it doesnt lurch forward unexpectedly and rear end someone...
PATIENCE ... JUST KEEP AT IT, AND SEE IF YOU CAN MAKE THE *WHISTLING* DROP DOWN, OTHERWISE DRIVE IT FOR A WHILE WITH THE *WHISTLING* AND SEE
IF IT CONTINUES. MINE EVENTUALLY WENT AWAY ... DON'T KNOW WHY.
>
>When I got the car in 2005, the tcv valve was disconnected, was it hard to adjust to get it right so some mechanics disconnected
it all together to save headaches? A friend had about 3 or 4 '59 caddys and he told me the nonac cars didnt have that tcv valve,
where they only installed on the AC cars???
YES, MOST MECHANICS EITHER DISABLE IT ENTIRELY OR PULL THE HOSE AND USE IT AS AN IDLE SPEED CONTROL.
dumps...@yahoo.com
You got it. Floats either set too low or binding on the walls of the carburetor. Pull top off carburetor and see how high/low the fuel is
