| Re: Carb / Vacuum issue [message #288655 is a reply to message #288652] |
Tue, 13 October 2015 14:59   |
bpimm
Messages: 211
Registered: June 2013
Location: Washougal Washington
Karma: 2
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Senior Member |
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Here is what I've found,
carb number 17054938 date code 1947 day 194 of 77
so its a 76-79, application year of 74 or 84
6th digit 1 or 2 = federal 4 or 5 = California this is a 9
7th digit = 3 = Cadillac
8th digit even = auto trans.
This is all the info I've been able to find so it doesn't even follow the numbering scheme. which the book I got this out of is typical. I haven't seen anything that would designate what engine it was for, what am I missing?
Brian & RaeDean
1973 26' #383
Washougal WA
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| Re: [GMCnet] Carb / Vacuum issue [message #288666 is a reply to message #288595] |
Tue, 13 October 2015 17:19 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Brian,
OK, to assist you with trying to make your carb work here's some links that may help you with that endeavor:
*****************************************************************************************************************************
Provided by Bill Freeman 11/20/2009:
http://oldcarmanualproject.com/manuals/Carbs/Rochester/QJet/index.htm
http://www.newagemetal.com/pages/GMC/73-78GMC.pdf
*****************************************************************************************************************************
Provided by David Orders 9/23/2013
Tiny URL: http://tinyurl.com/pfjna85
Full URL:
http://www.amazon.com/Rochester-Carburetors-Doug-Roe/dp/0895863014/ref=sr_1_1?ie=UTF8&qid=1379874674&sr=8-1&keywords=quadrajet+hp+bo
oks
*****************************************************************************************************************************
Provided by Emery Stora 4/12/2009
GM used seven different carbs for the GMC motorhome:
455 Engines:
73 and 74 GMC's had P/N 7043254
75, 76 and early 77 GMC's had P/N 7045254 and California had P/N 7045554
403 Engines:
77 GMC's had P/N 17057254 and California had P/N 17057559
78 GMC's had P/N 17058254 and California had P/N 1758559
These carb numbers can be found on the left side of the carb, stamped on the flat surface close to the secondary throttle shaft.
There is also a date code (4 digits) stamped in the same area:
73 to 76 coaches had a number starting with 70
77 & 78 carbs start with 170
Some parts used in the 170 carbs are quite different from those used in the 70. DO NOT INTERCHANGE parts between these two series.
One example is the primary metering rods. They are .080" shorter in the 170 series, they had a different taper to the rods and they
used different size primary jets.
The rods for the 70 series carbs will be stamped D-50. (7046338) I am told that this was used ONLY in the GMC motorhome carbs.
The 170 series are different.
All GMC carbs used the same secondary metering rods. These will be stamped with a CJ.
The proper power spring for the GMC is #7036019 which has an operating range from 4" to 8" of vacuum.
One problem that some people have had is the use of gaskets from an unknown kit. There are changes in the air passages in the carbs
and it is easy to install a gasket that covers an air passage hole and that will make the carb perform improperly.
The Delco overhaul kit for the 73-74 is 7046812. For the 75-76 (NOT California!) it is 17051886
*****************************************************************************************************************************
To assist other GMC owners that might be interested in obtaining a rebuilt Q-Jet from Dick Patterson here's the procedure:
1) Check your carb for the part number: 7043254, 7045254, 7045554, 17057254, 17057559, 17058254, or 17058559
2) Call Dick and he will give you instructions on how to verify that the core you have is a good core.
http://www.springfield-ignition.com/gmc-motorhome/carburation/
3) Send him the carb and he will rebuild it and send it back.
You can also contact Applied GMC:
http://www.appliedgmc.com/prod.itml/icOid/570
Cost of rebuild is $390
Cost of core is $280
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Brian Pimm
Dick's website says he will only work on the proper number carbs, the one I have is not one of the proper numbers for the coach, so
no I haven't. between the $600 rebuild and the $300 core, I can fuel inject it for about the same or less. Plus I don't know if
there are any cores available with the right numbers. At this point I'm just trying to get this carb to work right to see if I can
tune it good enough. :(
--
Brian
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Carb / Vacuum issue [message #288669 is a reply to message #288659] |
Tue, 13 October 2015 17:38 |
bpimm
Messages: 211
Registered: June 2013
Location: Washougal Washington
Karma: 2
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Senior Member |
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Loffen wrote on Tue, 13 October 2015 14:15Just remember that the tread is regarding a 70 series carb not the newer 170, jet and rod size should work but the 170 series rods are a little bit different so you can not use the part # I listed for the 70 series carb
Yep I caught that... from the part numbers I found on bob drews photo site from the links provided by mercdave it looks like I have 70 series rods in this 170 series carb, and not even the same ones 2 different ones, I have a 44B and a 43B in 70 jets. The 170 series GMC carb should have 55M rods but I don't know the jet size I found a PN to metering rod number chart but haven't found the same for the jets. Jet PN is 7031975, maybe it's a 75 by the number. I'll keep looking.
Found a reference that said the jet PN last 2 digits are the jet size so I need some 55M rods and 75 jets to get to where the 403 came stock, that should be a good starting point.
Brian & RaeDean
1973 26' #383
Washougal WA
[Updated on: Tue, 13 October 2015 18:09] Report message to a moderator |
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| Re: [GMCnet] Carb / Vacuum issue [message #288693 is a reply to message #288655] |
Tue, 13 October 2015 21:07 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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Brian,
The big Rochester Book says your carb is a service replacement for 73-74 350
& 455 Oldsmobile engines
Your original jets were 69s.
Gary Kosier
77PB w/500Cad
Newark, Ohio
--------------------------------------------------
From: "Brian Pimm"
Sent: Tuesday, October 13, 2015 3:59 PM
To:
Subject: Re: [GMCnet] Carb / Vacuum issue
> Here is what I've found,
>
> carb number 17054938 date code 1947 day 194 of 77
>
> so its a 76-79, application year of 74 or 84
>
> 6th digit 1 or 2 = federal 4 or 5 = California this is a 9
>
> 7th digit = 3 = Cadillac
>
> 8th digit even = auto trans.
>
> This is all the info I've been able to find so it doesn't even follow the
> numbering scheme. which the book I got this out of is typical. I haven't
> seen anything that would designate what engine it was for, what am I
> missing?
> --
> Brian & RaeDean
>
> 1973 26' #383
>
> Washougal WA
>
> _______________________________________________
> 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
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