Home » Public Forums » GMCnet » 403 Carburetor Jet and Metering Needle Size
| 403 Carburetor Jet and Metering Needle Size [message #358409] |
Tue, 08 September 2020 09:36  |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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My original carb had the fuel filter housing JB Welded in. In order to get the coach running, I bought a used carb from Chuck Boyd from a 1978 coach. Supposedly, the 1977 and 1978 carbs are identical. They even have the same number except for the year designator. And this one was labeled REMANUFACTURED.
When I pulled the top off the new carb, it was obviously going to need gaskets, pump, etc, so I ordered a good kit and bought Cliff Ruggle's Quadrajet book. I used to build Quadrajets back in the day, but this book is very helpful.
Anyway, what I read in Cliff's book took a little air out of my sails in that he states remanufactured carbs were built with a generic jet and needle combination so they would run several different vehicles with some level of success, but they are not tuned vehicle specific. That means it most likely does not have the TZE factory original jets and needles. I'm not so much concerned with the secondaries, but I would like to get the correct jet/needle combination for it on the primaries.
I'm also going to have to put bushings in the base plate, as the throttle shaft bores are worn, a typical problem for these.
So, does anyone know what the factory jet/needle combination was for the 1977/78 403 for our coaches?
Thank you.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: [GMCnet] 403 Carburetor Jet and Metering Needle Size [message #358411 is a reply to message #358409] |
Tue, 08 September 2020 10:17  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Greg,
Just call Dick patterson as he has all that info.
If you needn his contact, call me.
On Tue, Sep 8, 2020 at 7:37 AM Greg Crawford via Gmclist <
gmclist@list.gmcnet.org> wrote:
> My original carb had the fuel filter housing JB Welded in. In order to get
> the coach running, I bought a used carb from Chuck Boyd from a 1978 coach.
> Supposedly, the 1977 and 1978 carbs are identical. They even have the same
> number except for the year designator. And this one was labeled
> REMANUFACTURED.
>
> When I pulled the top off the new carb, it was obviously going to need
> gaskets, pump, etc, so I ordered a good kit and bought Cliff Ruggle's
> Quadrajet
> book. I used to build Quadrajets back in the day, but this book is very
> helpful.
>
> Anyway, what I read in Cliff's book took a little air out of my sails in
> that he states remanufactured carbs were built with a generic jet and needle
> combination so they would run several different vehicles with some level
> of success, but they are not tuned vehicle specific. That means it most
> likely does not have the TZE factory original jets and needles. I'm not so
> much concerned with the secondaries, but I would like to get the correct
> jet/needle combination for it on the primaries.
>
> I'm also going to have to put bushings in the base plate, as the throttle
> shaft bores are worn, a typical problem for these.
>
> So, does anyone know what the factory jet/needle combination was for the
> 1977/78 403 for our coaches?
>
> Thank you.
>
>
> --
> Greg Crawford
> Knoxville, TN
>
> 1977 Royale
> 403
> Rear Bath
> American Eagle Wheels
> Alex Sirum Quad bags
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.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: 403 Carburetor Jet and Metering Needle Size [message #358422 is a reply to message #358409] |
Tue, 08 September 2020 14:33 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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Jim, thank you. Dick emailed me the information directly. Thank you Dick!
Oh, and FYI, he said the main jet is: 1977 403 main 75, rod 54M Calif. main 78, rod 54M
1978 403 main 74, rod 54M Calif. main 78, rod 54M
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: 403 Carburetor Jet and Metering Needle Size [message #358467 is a reply to message #358409] |
Thu, 10 September 2020 10:00 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Well that seems very odd that Caif emissions would use several sizes richer jets than Federal. Maybe to limit NOX? At the expense of higher HC emissions? Anyone know?
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: 403 Carburetor Jet and Metering Needle Size [message #358507 is a reply to message #358409] |
Sat, 12 September 2020 08:56 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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For us Alabama boys living in Georgia, moving from California to Colorado is simply jumping out of the fire and back into the frying pan 
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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