| Carburetor [message #147053] |
Wed, 19 October 2011 12:29  |
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It appears that my carb is from a 75 Chevy; Dick Patterson says it won't work well on my '73, so I'm looking for a 7043254 Rochester; I've posted on the swap side also, but just in case someone missed it there, wanted to post here. Per Matt Collie, it may have had something to do with the demise of both of my head gaskets. I'm having the heads rebuilt now with new intake valves as some of the stems were blue,dinged up from heat or something. W/O starting new oil wars, my rebuilder says that Rotella (old) is not so good, due to the fact that the diesel detergents attack the ZDDP. He has recently atttended some oil seminars and found this out. He recommends Joe Gibb oil. I want a carb w/o the warped body, obviously. Any NOS out there?
geo groth '73 260 Sequoia
Carson City Nevada 89703
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| Re: Carburetor [message #147069 is a reply to message #147053] |
Wed, 19 October 2011 14:17  |
Kirk
Messages: 80
Registered: April 2008
Karma: 0
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George. I can loan you one until you find a keeper. I installed TBI but want to keep the carb in case I move to a smog test area some day. I can bring it on our next trip to Carson City. Email me off net. Kirk in Yerington
Kirk & Eloise Yeager -
Motorcyclists/RVers/Dog Lovers -
77 Royale 455/TBI/3:55 -
49ers - N. Nevada -
NdnKirk at Gmail dot com
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| Re: Carburetor [message #147074 is a reply to message #147053] |
Wed, 19 October 2011 14:36 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Yes, the detergent works agains the ZDDP is what I was taught. Diesel has high detergent for combustion byproduct suspension.
Diesel has higher ZDDP to counteract the negative effects of the detergent. In the end I'm not sure which wins. I was using Rotella 5W-40 full syn in CI-4 but that's no longer available as it's now CJ-4. Rotella is a brand name for many different products both syn and dino so it's best to say specifily which one and not "Rotella". Same goes for Mobile 1 but even more so as so many products to list in the Moble 1 family.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Carburetor [message #147083 is a reply to message #147053] |
Wed, 19 October 2011 15:36 |
kelvin
Messages: 608
Registered: February 2004
Location: Eugene, OR
Karma: 0
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Senior Member |
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I'm in the same boat, George. Well, sort of.
My carb is a medley of Q-jet parts. Most of it came from Autozone (to
replace the '76 Caddy carb my '73 230 came with ) and then I came across
a very warped 7043254 Q-Jet that I scavenged for all the GMC specific
parts I could remove and install in the Autozone carb.
My Combo-Q-Jet works pretty well but I'd really love to get a good 455
Q-jet and see what that did for drivability and mileage. I just know
there's another 1-2 mpg to be had with the right carb.
Anyway... if someone has ANOTHER spare carb after George gets his I'm
interested. I'd thing a good, unwarped core should be worth $100 or so.
All the EFI conversions should mean the market is flush with good cores, no?
Anyone need a '76 Caddy carb for their Cad 500? Got a spare here...
Kelvin
'73 23' in Eugene, OR
>
> It appears that my carb is from a 75 Chevy; Dick Patterson says it won't work well on my '73, so I'm looking for a 7043254 Rochester; I've posted on the swap side also, but just in case someone missed it there, wanted to post here. Per Matt Collie, it may have had something to do with the demise of both of my head gaskets. I'm having the heads rebuilt now with new intake valves as some of the stems were blue,dinged up from heat or something. W/O starting new oil wars, my rebuilder says that Rotella (old) is not so good, due to the fact that the diesel detergents attack the ZDDP. He has recently atttended some oil seminars and found this out. He recommends Joe Gibb oil. I want a carb w/o the warped body, obviously. Any NOS out there?
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| Re: [GMCnet] Carburetor [message #147111 is a reply to message #147083] |
Wed, 19 October 2011 19:34 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Kelvin
I attempted to send you a private email but it bounced.
Your site says:
Unable to deliver message, storage allocation exceeded.
Emery Stora
On Oct 19, 2011, at 2:36 PM, Kelvin Dietz wrote:
> I'm in the same boat, George. Well, sort of.
>
> My carb is a medley of Q-jet parts. Most of it came from Autozone (to
> replace the '76 Caddy carb my '73 230 came with ) and then I came across
> a very warped 7043254 Q-Jet that I scavenged for all the GMC specific
> parts I could remove and install in the Autozone carb.
>
> My Combo-Q-Jet works pretty well but I'd really love to get a good 455
> Q-jet and see what that did for drivability and mileage. I just know
> there's another 1-2 mpg to be had with the right carb.
>
> Anyway... if someone has ANOTHER spare carb after George gets his I'm
> interested. I'd thing a good, unwarped core should be worth $100 or so.
>
> All the EFI conversions should mean the market is flush with good cores, no?
> Anyone need a '76 Caddy carb for their Cad 500? Got a spare here...
>
> Kelvin
> '73 23' in Eugene, OR
>
>>
>> It appears that my carb is from a 75 Chevy; Dick Patterson says it won't work well on my '73, so I'm looking for a 7043254 Rochester; I've posted on the swap side also, but just in case someone missed it there, wanted to post here. Per Matt Collie, it may have had something to do with the demise of both of my head gaskets. I'm having the heads rebuilt now with new intake valves as some of the stems were blue,dinged up from heat or something. W/O starting new oil wars, my rebuilder says that Rotella (old) is not so good, due to the fact that the diesel detergents attack the ZDDP. He has recently atttended some oil seminars and found this out. He recommends Joe Gibb oil. I want a carb w/o the warped body, obviously. Any NOS out there?
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: Carburetor [message #147137 is a reply to message #147076] |
Wed, 19 October 2011 21:15 |
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Hi Phil, yes Greg is the one that rebuilt the heads, but don't know that he did anything wrong. My rebuilder in Reno says probably got hot, oxygen starved or combination thereof. I don't remember it getting very hot, like 220F. Also the fact that I didn't have the correct carb on it may have contributed. Hopefully a good rebuild, stainless valves, good carb and good juju will do the trick. Thanks for input.
geo groth '73 260 Sequoia
Carson City Nevada 89703
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| Re: Carburetor [message #147146 is a reply to message #147137] |
Wed, 19 October 2011 21:48 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Sounds like Aggie got to pop out your valves after all. When he did the valves on my engine he didn't use stainless valves? Did he say why he thought they are necessary now? Did he have a thought on why that cylinder was scuffed ? Did he think the Rotella oil played a part?
Roy
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Wed, 19 October 2011 21:51] Report message to a moderator |
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| Re: Carburetor [message #147201 is a reply to message #147146] |
Thu, 20 October 2011 12:00 |
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| roy1 wrote on Wed, 19 October 2011 19:48 |
Sounds like Aggie got to pop out your valves after all. When he did the valves on my engine he didn't use stainless valves? Did he say why he thought they are necessary now? Did he have a thought on why that cylinder was scuffed ? Did he think the Rotella oil played a part?
Roy
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He said he almost always uses SS valves now. I didn't ask about the scuff as I'm sure he'd say he'd want to see it. He did say that the Rotella was going to damage the engine if his info on oil was correct and to use something else like Joe Gibbs. As you may have read, Kirk in Yerington has offered me a loan carb and I'm going to get it. I had told him that Dick P. recommended SI SS valves.
geo groth '73 260 Sequoia
Carson City Nevada 89703
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| Re: [GMCnet] Carburetor [message #147221 is a reply to message #147129] |
Thu, 20 October 2011 19:03 |
klassic kampers
Messages: 93
Registered: July 2008
Location: greer,s.c./ellijay,ga
Karma: 0
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I will be for sure the only one on this site to state this, but(in MY opinion) other q-jets can be made to function very well on the GMC...todays gasoline is not the same as it was in 1970s and there were some engineering improvements made on q-jets up to the computer controlled units....
apologizing to all in advance, mike.......
Mike Stewart
1973 GMC 26' Canyonlands /
1973 B.S.A. B50 street tracker-----
Greer,S.C/Ellijay,Ga
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| Re: [GMCnet] Carburetor [message #147231 is a reply to message #147221] |
Thu, 20 October 2011 19:30 |
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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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Mike,
You may be correct, however, Dick Paterson (DA MAN) when it comes to rebuilding Q-Jets WILL NOT accept any other carb for
rebuilding.
I reckon the only way to determine that a non-GMC Q-Jet could perform as well as a GMC Q-Jet would be do a dyno run on the same
engine with both carbs and compare the test runs.
Now I'M going to cop flack from guys that say their GMC runs just great with another model of Q-Jet, or Holley! ;-)
Regards,
Rob M.
-----Original Message-----
From: mike stewart
I will be for sure the only one on this site to state this, but(in MY opinion) other q-jets can be made to function very well on the
GMC...todays gasoline is not the same as it was in 1970s and there were some engineering improvements made on q-jets up to the
computer controlled units....
apologizing to all in advance, mike.......
--
mike stewart,
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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: [GMCnet] Carburetor [message #147235 is a reply to message #147221] |
Thu, 20 October 2011 19:52 |
Manuel B
Messages: 19
Registered: March 2006
Location: Northeast Alabama
Karma: 0
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Junior Member |
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There are also different Q-jets for different GMC's, 1973-74 is not the same as 1975-76, and there were Federal and California versions, and the 1977 403" is not the same as the '78 403" carb.
When I sent one off they rebushed the throttle shaft holes because over the years they wear the holes and suck air and run lean = hotter.
[Updated on: Fri, 21 October 2011 09:43] Report message to a moderator |
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| Re: Carburetor [message #147240 is a reply to message #147201] |
Thu, 20 October 2011 21:26 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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While you have it apart stainless valves is probably a good idea.It sure can't hurt. I'm using Rotella in mine but it is Synthetic and CI4+ that Dick used to recommend so I guess I'll stick with it.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Carburetor [message #147241 is a reply to message #147235] |
Thu, 20 October 2011 21:51 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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| Manuel B wrote on Thu, 20 October 2011 19:52 |
There are also different Q-jets for different GMC's, 1973-74 is not the same as 1975-76, and there were Federal and California versions, and the 1977 403" was another carb.
When I sent one off they rebushed the throttle shaft holes because over the years they wear the holes and suck air and run lean = hotter.
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on the California carbs what jets and rods should i be using? i put in #71 jets and 50D rods but it runs really lean; plugs are real white on the porcelain part.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: Carburetor [message #147243 is a reply to message #147053] |
Thu, 20 October 2011 22:45 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Matt... there was an oil question in the intial carb message.... hence the forks in the road.... and I believe the GMC Qjet uses a special tripple tapered rod in the primaries that no other vehicle used. If I can find my Qjet book I'll copy that page to the photo site. Great book ,its somewhere.
John Lebetski
Woodstock, IL
77 Eleganza II
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