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| [GMCnet] Carbureter kit needed [message #120537] |
Fri, 01 April 2011 20:18  |
Richard Brown
Messages: 281
Registered: May 2009
Karma: 1
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Can anyone tell me which rebuild kit to get to fix my carb? I took it out to get it inspected today & didn't make it. I blew out the line from the pump back to the tanks & it seemed clear.It will barely run & backfires at anything above idle & smell gas when it's acting up. I feel like it's the carb, but it could as easily be the fuel pump. I checked the filter the carb inlet & there was pressure when I loosened the line, tho... I've got to get this thing fixed tomorrow so I can get it out of a lady's yard.
As usual, it never acts up in the yard...
Richard & Carol Brown
1974 Eleganza SE
"DILLIGAF"
Lindale, Tx. 75771
903-881-0192
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Richard & Carol Brown
1974 Eleganza SE
1174 Hickory Hills Dr.
Murchison, TX. 75778
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| Re: [GMCnet] Carbureter kit needed [message #120548 is a reply to message #120547] |
Sat, 02 April 2011 00:54  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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To get the right kit, you'll need to take the carb # off the Left side
of the carb.
On Fri, Apr 1, 2011 at 10:02 PM, rl caudle <rlcaudle@charter.net> wrote:
> be sure to check the coil and points also for backfire, especially the
> coil......if it runs fine in the yard, maybe the coil is actingup when it
> gets warm
> ----- Original Message -----
> From: "Richard Brown" <wings77sporty@sbcglobal.net>
> To: <gmclist@temp.gmcnet.org>
> Sent: Friday, April 01, 2011 8:18 PM
> Subject: [GMCnet] Carbureter kit needed
>
>
>> Can anyone tell me which rebuild kit to get to fix my carb? I took it out
>> to get it inspected today & didn't make it. I blew out the line from the
>> pump back to the tanks & it seemed clear.It will barely run & backfires at
>> anything above idle & smell gas when it's acting up. I feel like it's the
>> carb, but it could as easily be the fuel pump. I checked the filter the
>> carb inlet & there was pressure when I loosened the line, tho... I've got
>> to get this thing fixed tomorrow so I can get it out of a lady's yard.
>> As usual, it never acts up in the yard...
>>
>> Richard & Carol Brown
>>
>> 1974 Eleganza SE
>>
>> "DILLIGAF"
>>
>> Lindale, Tx. 75771
>>
>> 903-881-0192
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 10.0.1209 / Virus Database: 1500/3545 - Release Date: 04/01/11
>>
>
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Carbureter kit needed [message #120559 is a reply to message #120548] |
Sat, 02 April 2011 09:06 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""Can anyone tell me which rebuild kit to get to fix my carb? I took it out
>> to get it inspected today & didn't make it. I blew out the line from the
>> pump back to the tanks & it seemed clear.It will barely run & backfires at
>> anything above idle & smell gas when it's acting up. I feel like it's the
>> carb, but it could as easily be the fuel pump. I checked the filter the
>> carb inlet & there was pressure when I loosened the line, tho... I've got
>> to get this thing fixed tomorrow so I can get it out of a lady's yard.
>> As usual, it never acts up in the yard...
""
They are still readily available. Take the part number of the carb to a Napa store and they have the kits. When rebuilding it, look very closely at the gaskets to make sure all of the various holes and cutouts are exactly the same.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Carbureter kit needed [message #120560 is a reply to message #120547] |
Sat, 02 April 2011 09:10 |
Eddie Pettit
Messages: 71
Registered: May 2009
Karma: 0
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Member |
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I had this exact same problem and let a friend talk me into rebuilding the
carb before I checked the electronics...
On Sat, Apr 2, 2011 at 1:02 AM, rl caudle <rlcaudle@charter.net> wrote:
> be sure to check the coil and points also for backfire, especially the
> coil......if it runs fine in the yard, maybe the coil is actingup when it
> gets warm
> ----- Original Message -----
> From: "Richard Brown" <wings77sporty@sbcglobal.net>
> To: <gmclist@temp.gmcnet.org>
> Sent: Friday, April 01, 2011 8:18 PM
> Subject: [GMCnet] Carbureter kit needed
>
>
> > Can anyone tell me which rebuild kit to get to fix my carb? I took it out
> > to get it inspected today & didn't make it. I blew out the line from the
> > pump back to the tanks & it seemed clear.It will barely run & backfires
> at
> > anything above idle & smell gas when it's acting up. I feel like it's the
> > carb, but it could as easily be the fuel pump. I checked the filter the
> > carb inlet & there was pressure when I loosened the line, tho... I've got
> > to get this thing fixed tomorrow so I can get it out of a lady's yard.
> > As usual, it never acts up in the yard...
> >
> > Richard & Carol Brown
> >
> > 1974 Eleganza SE
> >
> > "DILLIGAF"
> >
> > Lindale, Tx. 75771
> >
> > 903-881-0192
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
> >
> > -----
> > No virus found in this message.
> > Checked by AVG - www.avg.com
> > Version: 10.0.1209 / Virus Database: 1500/3545 - Release Date: 04/01/11
> >
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
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| Re: [GMCnet] Carbureter kit needed [message #120581 is a reply to message #120578] |
Sat, 02 April 2011 12:35 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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>
The GM part number for the kit is:
73-74 7046812
75 on 17051886
Here is a very good writeup on the overhaul that Brent Covey wrote back in 2001:
-------------------------------------
Theres a few things to pay extra close attention to-
All carb kits and parts within them are ordered by looking them up relative
to the carb number stamped into the carb body. This number will start out
with "70xxxxx" or "170xxxxx" and you'll need that to order the goodies for
the rebuild.
Most GMC carbs will have very little wear as this is something that occurs
more in high city traffic mileages, not just zooming down the highway.
Every time you encounter a black coloured foam float, replace it. Some GMC's
use a brass one which you can shake and see if its pinholed and allowed
liquid inside. Most are fine.
ALWAYS buy a new vacuum break diaphragm, this is the little bellows thing
that pulls the choke open, located at the passengers side front of the carb.
These are the #1 failure in carbs, and cause flooding and hard starts when
they fail. A used one is OK to use, but make sure you have a spare anyhow,
and carefully check that it holds a vacuum and pulls the choke open when
vacuum in applied.
Never remove the throttle plates or shafts or choke plate/secondary air
valve unless you are replacing them, as the screws often break off and are
in a position if they fall out the engine will inhale them, which is bad
news.
The vacuum break adjustment is altitude sensitive. The kit instructions do
not make it clear how its adjusted, but the essence is, it should open about
3/16" when the vacuum break diaphragm has vacuum applied to it. This is
approximately the distance the little groove embossed into the choke flap is
wide. Once its on, you may need to fiddle a little with this setting, it
needs to open less at low altitudes than higher ones.
Main jets need a PERFECT fit screwdriver to remove them. They can strip and
tear up with the wrong one, so get a really tight fitting screwdriver for
them. A sharp blow to the handle of the screwdriver with a light tool will
usually aid in breaking them free, they like to get stuck in there.
Retain the original GMC main metering rods, they're perfect for the GMC.
Jets can be changed to increase mixture strength a little, all GMC's should
use at least a '70' jet, and some could benefit with as much as a 74.
Basically as a rule of thumb go 3-4 jet sizes richer than whats stock and
you should be OK. At altitudes over 3000', #71 is fine for most people. At
5000'+ 70 will do. Jets have a part number ending in a two digit suffix that
designates their size, a 0.070" opening in a jet is a "XXXXX70" jet as
example. The prefixes are determined by carb family, and can be looked up in
the book, jets are about $3 each from GM.
The secondary air valves are opening too soon on most carbs, you should have
a close look at yours and make sure you understand where the adjustment is
located. Theres a set screw beneath the carb top, upside down that locks the
screw visible inset in the passengers side rearward edge that adjusts spring
tension. Double check lockout operation, not solely for locking out, but
also for releasing the air valve again as well.
Float settings aren't especially critical, go with the book on those. Be
sure the needle is hanging off the rearward edge of the float arm, not
hooked thru the holes in the arm which many people do. Be sure to stretch
the float hinge axle (C shaped heavy wire thing) open a bit to ensure when
the carb top goes back on it compresses the axle enough to ensure the float
has a good fulcrum to seat the valve with.
Make sure you install the choke seal and plastic hollow pin between the
housing and carb body. The choke must be adjusted so that it is strong
enough to just close the choke well at room temperature, you need to
slightly open the throttle for this. Check that the fast idle cam behind the
choke is pulled to the top step when the choke is closed and throttle is
released.. Adjustments of the choke spring are best carried out with the
plastic choke housing cover loose enuf to turn with your thumbs, and the
screws out. The apparent screwdriver slot in the plastic cover will break if
you attempt to use a screwdriver usually.
The plugs in the bottom of the carbs can work loose, and this usually
manifests itself as high fuel consumption, and very slow starts after you
have let it sit a few hours with a hot engine. You can inspect them for
signs of leakage, usually they're OK, and a dollop of some non-fuel-soluble
sealant will keep them dry usually. You can fix a leaking plug by judicuious
restaking of it, but if you drive the plug too far in, you'll possibly block
the passage its for. The plugs are self evident from their grey colour.
Be sure to double check screw tensions just before you install the carb as
well.
Its imperative of course that you take your time and have very clean parts
to work with. Invest in some carb cleaner and let it soak overnight.
Extremely stubborn deposits will usually yeild to Oven Cleaner, but this
will eat the castings fast if not supervised, washed in water thouroughly,
and de-activated with acid, such as white vinegar. You MUST pay close
attenbtion if you use a caustic cleaner, and be sure you've soaked it in
vinegar etc very well after, and rinsed in water.
WD-40 makes a reasonably good source of 'compressed air' for cleaning
passages. The engine will also start and run OK on WD40 if you want to prime
it a little thru the bowl vent. Whatever you do, make sure its clean as you
can get it, before you reassemble it.
Most carbs will look pretty good and only need a kit and slight tweaking of
the adjustments.
The big fuel filter nut is 1" and must be tightened carefully so as not to
strip the threads. When you reconnect the smaller fuel line to it, use a 1"
wrench (many crescent wrenches will reach 1" satisfactorily) and bend the
tube slightly in the direction of 'loosening it' while you tighten the flare
nut on the end the last bit, which will put some tension in the direction of
'self tightening' in the tube and help keep it tight. You will need a flare
nut wrench to loosen the fuel line, buy a TOP QUALITY one, the cheap ones
are as good as useless. If you just cant get it apart, taking it off in the
first place, Vise Grips will usually do it OK, or you can cut the line and
use a six point socket to get the flare end out and replace the steel fuel
line later. Dont re-use a steel line with a damaged flare, rounded off or
manhandled nut, or a kink in it, its a fire risk.
Set Idle mixtures once the new carb is on by 'lean roll'. Test secondary
airvalve operation, and adjust as neccesary, and next day on a cold engine,
check the cold starting and fast idle, and tweak if need be.
Thats basically most of it. I am sure I've forgotten something I'd have
thought of if I had one right here, and of course, if you see anything awry,
find out what you need to do.
As always, any carb or fuel system component needs doubly careful assembly
as any leak is a terrible fire risk. Be extra careful when you do this sort
of work and make CERTAIN that if you smell fuel you stop AT ONCE and
investigate it. This is doubly important now that the Reformulated fuels
with heavy Oxygenate content are causing deterioration of soft carb
components at a high rate, and much faster than we were used to in years
past.
Good luck with your QuadraJet, you should be able to do a very good job at
home if you take your time.
Brent Covey
Vancouver BC
--------------------------------------------------------------
It can be a lot of work to get it right. If you really want to get it right then order a rebuilt from Dick Paterson and send him your core.
He can be contacted at:
dick@paterson-gmc.com
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] book [message #120589 is a reply to message #120588] |
Sat, 02 April 2011 14:29 |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
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Senior Member |
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Ken, I bought that book a while ago. Read it. Then decided to send the carb
to someone who knew what they were doing. Best $15.00 I ever spent.
Thanks
Gary and Joanne Worobec
1973 GMC Glacier
Anza, CA
----- Original Message -----
From: "Ken Henderson" <hend4800@bellsouth.net>
To: <gmclist@temp.gmcnet.org>
Cc: "Richard" <bukzin@gmail.com>
Sent: Saturday, April 02, 2011 12:04 PM
Subject: Re: [GMCnet] book
> Even though I have EFI, I think that's a book that should be in my
> library.
> I just ordered it from Amazon for $14.93, with free 2 day shipping using
> my
> Prime membership.
>
> My son's still running a Q-J so he'll probably wind up with it.
>
> Ken H.
>
>
>
> On Sat, Apr 2, 2011 at 1:07 PM, Mike Teets <teamteets@gmail.com> wrote:
>
>> And here is a link to find it in libraries near you...
>>
>> http://www.worldcat.org/title/tune-rebuild-or-modify-rochester-carburetors
>>
>>
>>
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